Glomerular filtration is the main life sustaining kidney function, and kidney stones can cause enough damage to lower it. Usually the reduction is very modest, but sometimes stones can cause kidney failure. This means, like all diseases, stones are best prevented as early and as completely as possible.
This ‘just the facts’ version tells about what filtration is, how physicians measure it, how much kidney stones lower it, and how often that occurs.
Two longer articles give the details. One is comprehensive. The other focuses on only kidney disease, but is long.
Much of this text is redacted from the other two articles. I left out pictures, data, and links to PubMed to emphasize the main points.
The featured painting is by You Si 游思 (b. 1954), based in Shanghai, China. He is the son of two artists who lived through the cultural revolution and paints in new ways. I think his work is gorgeous but could not find a serious biography or critical study, or any museums that show his work.
What Filtration Is
Our two kidneys are each made up of about one million nephron units. A nephron is a complete and complex structure that begins its function by filtering from blood plasma a clear solution of water and small molecules. That filtrate enters the long loopy tubule of the nephron that reabsorbs a vast fraction of water and salts back into the blood leaving behind only that destined for export out of the body.
The glomerulus, a tuft of capillaries nestled in a tiny cup that drains into its tubule, performs this filtration. So we name it glomerular filtration rate, or GFR.
Blood flow and pressure from the heart drive filtration, but kidneys can regulate its rate. The cells that line the tubules regulate what fractions of innumerable individual salts and small molecules are taken back or let go into the urine.
Filtration Keeps Us Alive
Filtration rids the blood plasma of metabolic wastes, like oxalate, and permits us to excrete the extra water, salt, and all other materials we might eat or drink every day. Without filtration we need dialysis or transplantation to continue living. So this kidney function stands above all the others. When physicians speak of kidney function, they mean, and measure, filtration.
Filtration and Kidney Stones
Kidneys filter copious volumes of water and small molecules – like calcium, oxalate, citrate, phosphate, uric acid, sodium – hundreds of distinct materials. They then return most of this flood – 100 to 200 liters a day of water alone – back into the blood keeping behind only what they destine for export as urine.
Because kidneys filter such vast amounts, very subtle variations in what they take back into blood can load the urine with stone forming salts like calcium and oxalate, and cause stones. In other words, stones arise in significant measure because of subtle imbalances between filtration and reabsorption of key materials like calcium, oxalate, citrate, and water itself.
The filtering system, though powerful, is delicate. Through obstruction, infection, loss of one kidney, or surgical trauma stones can injure it. Such injuries reduce the ability of kidneys to protect the body, and when severe can lead to chronic kidney disease and even need for dialysis or transplantation.
How We Measure Glomerular Filtration
Serum Creatinine
Muscles make creatinine steadily and send it into the blood. Like almost all small molecules, kidneys filter it. Serum creatinine therefore reflects the balance between muscle production and filtration. When filtration falls serum creatinine rises. It is like your golf score – bad day, higher score. Serum creatinine gauges filtration adequately enough for clinical practice. But because kidneys not only filter creatinine but also secrete it from blood into urine, creatinine overestimates true filtration.
eGFR
To get a better estimate, scientists compared serum creatinine to true GFR in reasonably large populations and calculated the best fit between them using regression techniques. The resulting regression equation gives estimated GFR, or eGFR, from serum creatinine, age, sex, and race. This highly derived index dominates medical practice. When physicians speak of reduced kidney function they mean reduced eGFR.
Kidney Function in Stone Formers
Average Function is modestly reduced
Our Own Patients
In our own patients, we found that stone formers have lower kidney function than normal people. The common idiopathic calcium stone formers are just slightly low. Likewise for those with primary hyperparathyroidism. But kidney function is reduced by about 20% in people who make stones because of bowel disease or diseases like renal tubular acidosis or cystinuria. Uric acid and struvite stone formers have even greater reductions.
US Health Surveys
The national NHANES data survey results showed modestly reduced kidney function in overweight people who had a history of stones. Women who formed stones had increased risk for serious chronic kidney disease, and even dialysis.
Olmsted County
This community uses Mayo Clinic for care so records are very complete. A history of kidney stones increased risk of CKD and eventual dialysis.
Large Reviews
Two extensive reviews of all published studies – not just the few I mentioned – concluded that where ever looked for, stone forming raised risk of high blood pressure, serious chronic kidney disease, and even dialysis.
Though Increased, Kidney Disease Rates are Not High
Stones raise the risk of serious kidney disease from the very low levels in the general population to higher though still low levels. The vast majority of stone formers do well and never have problems that require special kidney care. Only rarely do stone formers need dialysis. But they can come to need such care more frequently than people who never formed a stone.
The message is obvious. Stone recurrence should be minimized through prevention efforts. Physicians who practice stone prevention need to measure eGFR appropriately, and if it begins to fall take proper steps to mitigate the causes of that fall.
Obstruction from stones always needs prompt, skilled, urological care that minimizes risk and trauma from surgery. Because silent obstruction can destroy a kidney, any symptoms that suggest new stone passage deserve urological attention.
High Blood Pressure
The NHANES and Olmsted County data show that a history of stones raises risk of elevated blood pressure. Loss of kidney function, even subtle, could raise blood pressure, and increased blood pressure can harm kidneys and reduce GFR. Unlike significant kidney disease, high blood pressure is easily treated to prevent strokes, heart disease, and kidney failure. But high blood pressure commonly escapes diagnosis and adequate treatment.
This means kidney stone prevention clinics are high blood pressure clinics, or at least a common place where high blood pressure can be first detected. All stone formers need to know their blood pressure and seek care if it is elevated.
Bottom Line
Stones are a painful and recurrent chronic disease that kidneys generally tolerate with at most a modest amount of injury and function loss. But compared to people without stones, those who make them have measurably increased risk of high blood pressure and loss of kidney function. Years of study have made clear that this disease demands attentive treatments aimed at prevention, and that surgeons who manage stones do everything possible to preserve kidney tissue.
My friend has bilateral multiple renal stone. Now obstruction removed by stenting. But still stones are in kidney. Initially his creatinine 4.8 after stenting it reduced to 4.1. Any possibility of reduction in creatinine after removal of stone?
Hi Vj, When the obstruction has been corrected the serum creatinine should fall to where it was before the obstruction. If that does not happen either the kidneys have been damaged by obstruction or there is another problem causing kidney disease. Primary hyperoxaluria or other very high oxalate conditions are always a worry in this kind of situation. I imagine his/her physicians are already looking at urine oxalate. There are other possibilities as well. Regards, Fred Coe
Hi, my friend is 17 year old. He eats non veg to considerable extent. His uric acid is 7.5 mg/dL and urine analysis reveal calcium oxalate crystals (+) in urine but the creatinine is 0.88 mg/dL, eGFR is 121 ml/min, urine normal in colour and not experiencing any pain. Should ultrasound scan be considered to rule out the possibility of kidney stone ? What could be possible reasons for calcium oxalate in urine, is it only the non vegetarian food a contributing factor ? Can calcium oxalate crystal be formed in urine without kidney stones ? How seriously should be considered for a 17 year old.
Hi Aditya, Such a high serum uric acid in a 17 year old is unusual and suggests such things as high blood pressure or disturbed renal function. Given the CaOx crystals his physicians may wish to measure 24 hour urine oxalate to be sure it is not high. His blood pressure would be of some import and can be measured at home with one of the many forearm digital machines now on the market. An ultra low dose CT can reveal stones far better than US and delivers very little radiation. His physicians may wish to consider it. Altogether it is the serum uric acid that most bothers me, and I am sure his physicians think the same. Regards, Fred Coe
My father 53 yrs old have stones in both the kidneys. GFR rate is 28ml/min for both kidneys combined. The uric acid is 6.9mg/do and creatinine is 6.9mg/dl. Doctor has mentioned that they will be operating in 2 days. He even mentioned about possibility of nephroctomy. Though he mentioned that they will be keeping a one month period before removing kidney. Is it possible to improve the functionality of kidney with stone removal?
Hi Rahul, I do not have enough information to really help here. But if stones are obstructing his kidneys or causing infection their removal may well improve kidney function.I hope so. Regards, Fred Coe
Doctor,
I had a two uric acid stones removed with laser lithotripsy. One was in my prostate, the other a 9mm stone in my left renal pelvis. I am obese. I have hypothyroidism and gout. My blood pressure is currently not high and I don’t yet show prediabetes.
I am trying to understand so e things that have happened since the surgery, but I don’t yet have the vocabulary to discuss them.
1. My ankles were swelling quite a bit prior to the kidney stone being removed. This subsided after the stone was removed.
2. I was secreting an abnormal amount of sebum, or some other substance through my skin. My head was a greaseball. After my stones were removed, this was seriously reduced.
3. The substance my skin was secreting would get in my eyes and leave them with a burning feeling. When I tasted it, it tasted very sharp. Almost like a lemon but not so pleasant. After the surgery, this stopped.
4. My energy and alertness levels seem to be up after the surgery.
I wouldn’t think this could’ve affected my physiology so radically, but it seems as. Where can I look to understand what has happened and why?
Hi Matthew, I cannot explain the skin changes, but I strongly recommend you discuss stone prevention with your physician to be sure you are taking potassium citrate or other alkali as uric acid stones can be prevented and even dissolved. Regards, Fred Coe
Hello Dr. I have been diagnosed of bladder and kidney stones. My two kidneys are having stones.
Can all be removed together? What’s the best way of treating the stones? I’m afraid of undergoing an operation. Is there any alternative?
Hi Francis, Your urologist will have to decide, but in general one would remove bladder and renal stones at one time if possible. The reason for the stones, and prevention of more is paramount. Here is a good primer of how to proceed. Above all, get the stones analysed! Regards, Fred Coe
I am 58. I just had my 3rd kidney stone soundwave surgery. The 1st was 4 years ago and the 2nd a year ago. My stones tested to be calcium oxalate the first time. I still have smaller stones in both kidneys. I have developed osteoporosis in the past few years.
I am changing to a low or no oxalate diet. What can I do to dissolve the smaller stones so they don’t get larger and have to do the soundwave surgery again? The surgery seems to be more painful and longer recovery each time.
Thanks
Hi Elizabeth, the combination of stones and bone disease suggests you might have idiopathic hypercalciuria as a cause for your stones. Have you had serum and 24 hour urine testing? If so, was your urine calcium above 200 mg/day? A low oxalate diet is a very weak aspect of prevention compared to changes in, for example, urine calcium when it is high. You cannot dissolve calcium oxalate stones, so the best outcome is to avoid more new stones. Thus prevention is so important for you. Regards, Fred Coe
Thank you!
Hi I am 68 I had a kidney transplant 7 years ago I still have my original 2 kidneys. My question is, can “non functioning” kidneys develop stones?
And side question, can Sarcoidosis cause, lead to, or mimic kidney failure or disease?
Hi Vera Love, Yes; end stage kidneys can form stones, often poorly mineralized. An ultra low dose CT will reveal those with reasonable mineral content. Sarcoidosis can cause stones and renal failure, from elevated serum and/or urine calcium, and from direct disease within kidneys. I hope these answers are helpful, even if a bit tentative for lack of detailed information. Regards, Fred Coe
Dear Fredric Coe, MD
My husband developed Kidney stones 7 years ago and has been having lithotripsy’s every 6-7weeks for all these years, alternating each side to manage the condition. His kidneys produce significant numbers of stones and they grow rapidly. He has seen 3 specialists and the only thing we have been told is he has sponge kidneys but no one seems to be able to say why he develops these stones. His health is deteriorating significantly and the pain is horrendous even with all the pain relief he takes. I am wondering if you have ever known of anyone else having this type of serious stone condition and if so any information you can provide me so I can follow this up with his dr would be very much appreciated. Regards
Michelle
Hi Michelle, of greatest import is what these many stones are made of – are they calcium oxalate, calcium phosphate? Sponge kidney is a very specific kind of disease, with a special appearance during ureteroscopy, and his urologist surely has already looked – although you say only that he has had lithotripsy. What I fear is that the many SWL are themselves damaging, as every 6 – 7 weeks is 8 or more a year for 7 years, or upwards of 50 procedures. Are these new stones or just fragments from a few large stones that SWL is not clearing? I would suggest discussing with his physician if it is not time for your husband to visit a specialized kidney stone center, as this many SWL procedures surpasses the usual situation and perhaps alternative surgical modalities might be considered. Likewise, you mention no special means for stone prevention, that surely is in order. I would hope that he will not continue to have SWL procedures at this rate long term. I view additional consultation as an important alternative from what you have told me. Regards, Fred Coe
Thank you for your reply. His stones are Calcium Oxylate. They are new stones forming not fragments, producing rapidly and grow quickly. He has medullary sponge kidney diagnosed and ulcerative colitis which is well controlled. He has had diagnostic procedures other than lithrotripsy, but again only treating the symptoms. We are in Australia, we have never been advised of a specialist kidney stone centre here? Is there anything diet or medication that can help slow them down or prevent. He is off to see his kidney specialist next week and if there is anything additional we could be asking him that would be appreciated. Thank you regards Michelle
Hi Michelle, He needs 24 hour urine testing to figure out what is causing the calcium oxalate stones. Ulcerative colitis can promote such stones because of low urine volumes from diarrhea, and if he really has Crohn disease with colon and small bowel involvement his urine oxalate may be high. All this is treatable but you need the urine testing to find your way. As for stone centers in Australia I looked on the web and found a few possible candidates. I do not know any of the people, however. I am still sceptical about MSK, and suspect it might be his bowel disease- very wild guess from 10,000 miles away! Regards, Fred Coe
Hi I had my first kidney stones removed when I was 19 years old I am 46 now and have recently had a number of stones removed from both kidneys, they are both badly scarred but functioning ok. My consultant has referred me as my urine Showa high calcium yet my blood calcium is low, he was baffled by this and unsure wether I should be on a high or low calcium diet, any ideas? I am awaiting an appointment with hormone people
Hi Jd, if you mean that serum calcium levels are indeed low – below the normal range – and urine calcium is high, you may have a specific genetic disease . Multiple gene variants are known, and most seem to alter the sensitivity of the calcium receptor. This article on the site gives some references to the general condition. Your ‘hormone people’ will have to sort this out for you. This is very important as you say you have kidney damage and stone prevention is therefore very critical. Regards, Fred Coe
I have two normally functioning kidneys, but chronically form sand and stones almost exclusively in the left one (20+ years). I have yet to find articles to explain why this happens, and the 3 specialists I’ve seen have offered no clues. Any ideas?
Hi Chris, C, I would have the sand analysed to find out what it is. If white, I presume it is a form of calcium phosphate. If red or orange, a form of uric acid. Being from one kidney is interesting, and perhaps you already know if there are stones or calcium deposits in that kidney. If not, you might want an ultra low dose CT to find out. Likewise, perhaps, that kidney has some drainage anomaly due to abnormal anatomy that favors crystal formation. Perhaps you might ask your physician if these ideas seem helpful or not. Regards, Fred Coe
I have 1 kidney having removed the right kidney due to RCC. Pathology reported I also had diabetic glomurosclerosis. After nephrectomy eGFR dropped from 73 to 36. A recent ultrasound detected a 7 mm stone in left kidney. It did not show up on presurgical FUB X-Ray (4 months ago) so my urologist says it does not require treatment. This sounds wrong. My nephrologist says its no concern because its enclosed within the parenchyma but this does not make much sense. My concern obviously is possible obstruction with only 1 kidney. That would not be good.
My urine pH has been running 5.5-6 so I suspect its a uric acid stone which explains why it does not show on X-Ray.
I also have proteinuria and a recent MRI says I have a number of tiny renal cysts but no mention of the stone, and perhaps neither is related to the stone. At 7 mm it was unlikely to have passed without my notice. I also have lower back/side pain that comes and goes and is not exercise related.
If I understand your posts I should probably be dealing more aggressively with the stone and hopefully get some improvement or at least stability to renal function with removal and preventive treatment. May have to check with another urologist and run some of your stuff past him/her.
Hi Pete, It sounds like diabetic kidney disease is a major issue for you, and your nephrologist is no doubt doing all she/he can to ward off further loss of function. In a diabetic with a stone like yours uric acid is a very high likelihood. Your physician can tell using the CT scan and measuring the radiographic density of the stone. Although potassium alkali may be limited from your reduced kidney disease and the effects of diabetes on renal potassium handling raising urine pH to dissolve uric acid and prevent stones and potential surgery are both important. I would ask your nephrologist about the matter. MRI will not show stones reliably. Regards, Fred Coe
Thanks Fred. I will do as you suggest.
Hi Pete, It sounds like diabetic kidney disease is a major issue for you, and your nephrologist is no doubt doing all she/he can to ward off further loss of function. In a diabetic with a stone like yours uric acid is a very high likelihood. Your physician can tell using the CT scan and measuring the radiographic density of the stone. Although potassium alkali may be limited from your reduced kidney disease and the effects of diabetes on renal potassium handling raising urine pH to dissolve uric acid and prevent stones and potential surgery are both important. I would ask your nephrologist about the matter. MRI will not show stones reliably. Regards, Fred Coe
Sir iam 22 iwas diagnosed with kidney stones 3 years back now also 5 mm 6mm stone’s creatinine level is 1.5
My doctor says it is normal it is due to stones shall i believe him
Hi Nisar, Your serum creatinine is high and that may reflect obstruction by a stone. I imagine your urologist has checked for this, which is very important. If there is no obstruction, your physician should consider causes of stones that also cause reduced kidney function. The most important of these is primary hyperoxaluria that is detected from the 24 hour urine. The other causes are numerous and your physician knows them and can determine if any are present. Your physician knows you case and I do not. Possibly you have recently passed a stone, or had surgery or shock wave treatment or infection, and any of these can lower kidney function briefly. If that is the case, your creatinine will fall to normal. Regards, Fred Coe
I’m 30 years old and my GFR is very low for my age, only 73 mL/min/1,73 m² but I don’t have any other disease associated like diabetis or high pressure. Ultrassound detected a small stone of 2.8 mm in the lower part of the kidney and nothing else abnormal. The stone never caused me any pain and I just discover its presence by the ultrassound. Sodium and potassium are in normal rate in blood and the urine test did not show the presence of protein. What can be causing my GFR to be so low? Also I don’t remember of having any urine infection. Help me please, I’ve been concerned about it for more than a year.
Hi 133odete, Your situation is complex: reduced calculated GFR using serum creatinine, no urine protein excess, and a small stone in one kidney by ultra sound with, I presume, normal size kidneys with normal tissue density. The latter two points are important. Blood pressure is normal, no diabetes. I would think you should have a nephrologist as one of your physicians, so she/he can sort this out. Possibly, serum creatinine is not a good marker for your GFR as some people do not secrete it and their blood values give false estimates. Possibly your kidney size or density on US are not normal. Possibly you have some cause of stones that is also a cause of kidney disease such as a very high urine oxalate level – 24 hour urine testing can tell this. A renal specialist is trained to get your answer, and I would urge you get one. Regards, Fred Coe
The US showed that my kidneys are in normal size and density. Also I already saw a nephrologist that ordered a creatinine clearance that showed the result of 73 mL/min/1,73 m². Probably my problem is high urine oxalate as you said and my nephrologist has already ordered a 24 hour urine testing to see the oxalate levels. Also I had already found some oxalate crystals in previous urine testing that I made in the past. So I think you may be right. Another question: can bowel problems as gluten sensivity cause oxalate to raise in urine? Assuming it’s a bowel problem with no other problem associated, can I revert the situation improving my bowel and raise my GFR again?
Hi 133odete, If your urine oxalate is high, and high enough to have injured your kidneys the problem is very significant. Bowel disease can raise urine oxalate if you have true gluten enteropathy. The problem with oxalate induced kidney disease is that lost function does not always return as fully as one would hope. So discovery and reduction of urine oxalate is imperative. Regards, Fred Coe
I have Wegeners desease and Sjogrens syndrome. Have frequent stone blockage. They are 90% phosphate stones. My average gfr over the past year is around 48% but have dipped in the low 30’s during stone occurrences. I have never passed one as they have always been surgically removed but was wondering if I could try or is it too dangerous to have blockage for that long with already reduced kidney function. Just hate having all these lithotripsy procedures.
Hi Steve, Given your underlying diseases, renal tubular acidosis does seem very likely. Kidney function loss may well be worsened by the phosphate crystallization. As for letting stones block your kidneys, it would be very unwise. Prevention of stones from acquired RTA is no small matter, and no trials exist given the small numbers of patients. This article gives a lot of background about RTA and also about ways to reduce stones. High fluids, and perhaps a thiazide type diuretic like chlorthalidone + potassium chloride to replete potassium losses might help. This is complex medicine, and your physicians no doubt realize that. Regards, Fred Coe
Hello – My Creatinine Serum Clearance is 61.31, have had two episodes with kidney stones about 10 years ago and past them successfully. Having middle lower right back pain for a few months now and wondering if there is an obstruction. Am female, 69 years old. Do you think it’s time to see a doctor? Thank you.
Hi Genevieve, The value you quote is estimated GFR (eGFR) calculated from your serum creatinine, and your value is just at the border of stage 2 and stage 3a chronic kidney disease. But in fact, millions of people are being labeled as chronic kidney disease by this calculation and almost all are simply older with older kidneys and not kidney disease if by disease we mean an abnormality from the expected course of aging. Even so, if you have had stones and you have pain suggesting a stone, obstruction is possible and it is essential your physician determine this. So please bring yourself to your physician and let her/him decide if things are abnormal or not in your urinary tract. Regards, Fred Coe
Hi,
I am a 55 year old, white, female and was experiencing right side pain which sent me to the ER. My metabolic panel showed the following and I am wondering if this is a cause for concern?
BUN-12
Creatinine-1.07
BUN/Creatinine Ratio-11
GFR- 57
Had a renal catscan which showed
“Imaging through the left kidney reveals possible mild dilatation of the lower pole collecting system. There may also be a slightly prominent extrarenal pelvis on the left. There is no evidence for renal mass or calculus on the left side.”
Have had two dilation’s done for urethral stricture was having difficulty starting a stream, spraying, straining. Procedures helped and am much better in that area. I thank you for your time.
Hi Lynne, I am not clear if you have stones or not. The CT seems to show no stones, but does show dilation of a lower pole collecting system. This is not clear to me, but perhaps your urologist understands it. Your pain was right sided but there is no mention of the right kidney on CT. Urethral stricture will not cause your reduced eGFR (57). The cause of the right sided pain seems unknown. I guess I would want to know what caused the pain, and why your eGFR is reduced – high blood pressure, diabetes, other? Regards, Fred Coe
Hi,
I have been complaining for burning after urinating for some time. And I develop sand stones frequently the first ones were 4 years back and then every 3 months I do have the same condition sometimes they are oxalate and sometimes are uric acid. Last blood test showed eGFR 84 and creatinine 1.11 . Doctor said no problem as long as no protein or there are no clues in the urine and blood tests for CKD. There is hameturia from time to time around where the numbers around 50 but the microscopic results shows negative WBC or RBC.
I forget to mention I did US and CT before and only tiny sand stones are found.
Should I worry about my kidney and how can I prevent recurring stones?
Thanks
Hi Moheb, No it is not good to be passing anything like sand. I also am not sure about the sand being uric acid and oxalate, and I presume it is mainly uric acid with some mixed oxalate. Uric acid is always from too acid a urine, and you should have 24 hour urine testing to confirm that and treatment to raise the pH of the urine. At your age such low pH is not usual, so maybe there is a reason – obesity, diabetes, high blood pressure? Regards, Fred Coe
Thanks. My Urine PH is 6 I learnt this is in normal range which is from 5-8. No history of diabetes. I am a bit overweight around 10 kilos more blood pressure is 135/95. I will ask my physician for the 24 hours test. I do suffer from IBS and high cholesterol which is managed by crestor. But is there is any relation between the low eGFR and the small stones?
Thanks again
Hi Moheb, You might find out what the sand is, as a clue to why kidney function is declining. The one small stone is not relevant but the sand is. The 24 hour urine is essential and may also give a clue. Regards, Fred Coe
Forget to mention I am 38 years old
Hi doctor,
I have an extensive history of kidney stones and have gone into complete kidney failure twice in the last 12 months. During my first episode in June 2019, my BUN level was 78, creatine 4.97, eGFR (non AA) a very low 12. I was hospitalized overnight and was able to leave the next day. The cause: obstructive kidney stones.
During my second episode in Nov. 2019, my BUN level was 58, creatine 2.00, and eGFR 36. The cause: you guessed it, stones.
I do have 3 herniated discs at S1, L4 and L5, but on some days my back hurts terribly at kidney level. One urologist told me it’s impossible for kidney stones to cause my back to hurt unless they are out of the kidney and passing through the ureter. I think differently. The CT scan I had in the Nov. episode showed a 6 mm calculi in the ureter and multiple bilateral nonobstructive calculi. The same urologist told me that some of the stones are too small for lithotripsy.
I’m suffering terribly, and I would greatly value your opinion. What should I do? See a different doctor?
Thanks for your help, Bob Bowen
Hi Bob, you have had severe and worrisome kidney failure from stones. Are these calcium or uric acid stones? Prevention is urgent. If possible you might consider a second opinion at a medical school center for stone prevention. Lithotripsy is inadvisable given several bouts of severe kidney failure. Your surgeon might want to consider ureteroscopy. It is not that your surgeon has not done everything within his/her range, it is just that your situation is more dire than usual and requires more than even a skilled urologist can manage. Each bout of kidney failure can leave residual kidney damage. Regards, Fred Coe
I am 69 years old. In early November i had surgery for 3 large uric acid stones apps 1.54 cm. In July, prior to these stones discovered in October, my creatinine level was 1.17 and my bun was .28. The day after the surgery my grr was greater than 60. 2 days after the surgery it was 56. Last week I received the results from my 24 hour urinalysis and everything was normal. That being said my creatinine level was 1.34, my bun 28 and grr 53. My surgeon didn’t seem alarmed and said that since the surgery was just over 10 weeks ago my blood tests will fluctuate and that as long as the urinalysis was normal to have another bloodiest in another 3 months. Should I wait or should I see a nephrologist for testing now? I want to be proactive should I have kidney disease. Please advise. Thanks so much. N
Hi Norm, Your physician is certainly not wrong, but if I were asked I would be sure that there is no obstruction of either kidney. If your surgery was a percutaneous procedure there is a lot of kidney trauma and it may take quite a while to heal. But obstruction is always a worry. Regards, Fred Coe
Hi! I am 21 years old and have at least 5 kidney stones in my kidney. I’m in really bad pain and my urologist said that there is nothing he can do. I also have swelling in my back where my kidneys are located. I dont really know what to do at this point..
Hi Breanna, I presume your stones are not obstructing, and that you are part of a large group of people with non obstructing stones and pain. Trials are lacking about whether surgical removal of the stones will help reduce pain. Prevention of more stones and more crystals may well help, however, and here is a good article about what to do. regards, Fred Coe
Hi Dr. Coe. I too have a non obstructing renal stone with pain. What is the article you speak of? Thank you.
Hi Rachel, this one. Fred
Thank you for explaining that nephrons are complete and complex structures that begin by filtering a clear solution from the blood plasma. My husband’s mom has been struggling with some kidney issues. I think they should look into a good nephrology treatment clinic that can help them know which treatment is the best for her.
Hi Charlotte, I would agree that with kidney issues your mother in law would benefit from nephrological care. Your comment is linked to a commercial site for kidney physicians, and I ban such on this university site, but given your apparent real issues have let the comment stay. I have little regard for nephrology practices that attempt to put their name up on sites as spam, but assume that is not the case here. Regards, Fred Coe
Could there be any relationship between breathing and kidney stone formation? For example, could deeper, slower breathing affect PH levels, Citrate levels, etc? I’m sure there is little research on this but could you see a mechanism that would connect the two? Thanks for considering my “not-so-in-the-box-idea”.
Hi Stavros, altering acid base status by increased or decreased CO2 clearance – what you suggest – can have little long term effects on urine pH because the kidneys will compensate. It is also not a good idea, so far as I can tell. As an example, during pregnancy respiratory CO2 clearance rises, but overall renal bicarbonate handling comes into a new relationship with blood CO2 and bicarbonate and urine pH can reflect food conditions as always. Regards, Fred Coe
Hi
I was discharged from the hospital. I have a 1.5cm obstructing kidney stone L ureter. The urologist feels it has been there for a while. I had grade 4 hydronephrosis. I had a nuclear renal scan that showed 13% functioning of the L kidney and 87% of the R. I had no pain just became very ill with chills, fever, vomiting and some L sided abdominal cramping.
To make a long story short. My creatinine is back to normal but my Urologist feels that the kidney was very damaged and the wall of the kidney is very thin. I currently have the nephrostomy tube and have a follow up appointment on monday. Dr. has been recommending that I have a nephrectomy. He said if I chose to keep the kidney I may end up with chronic infections because of the poor function.
Does kidney function improve over time….what are your thoughts?
Thank you
Hi Rose, I am afraid that you have lost most of that kidney and I do not believe it will improve. Your physician is not wrong given the possibility of infection. It is big loss, and you should make all efforts to avoid more stones. Regards, Fred Coe
Hi Dr ,
I had left ureteric stone 12 mm in 2007 which was removed by a Urologist but I still have 6 mm stone in my right ureter which is non obstructive, which was 4 mm till 3 years back.
My creatinine is around 1.2 and I have increased frequency of Urine. I am a non diabetic , Cholesterol 280 and eGFR was 81 three years back.
What should I do , I am worried ?
I am a Pediatrician FYI.
Regards,
Dr Pankaj Bohra
Dear Dr. Bohra, I presume there is no dilation of the upper tract but the stone is growing in the ureter. I would think simple removal via URS with laser would be the best idea if your surgeon think that is practical – as the stone grows it may obstruct, and without pain. You do not mention the stone location but urinary frequency suggests it is at or near the UV junction. The reduced eGFR is hard to assess as I do not know your age, but I do not think it is from the stone if it is really not obstructing. Regards, Fred
Hi, My dad is 68 years and From Ultrasound report, it has impression of multiple left distal ureteric calculi near bladder with Hydroureteronephrosis, Left renal cysts, Irregular outline of right kidney likely due to scarring/previous infection, CMD maintained in both kidney; mild edematous parenchyma of left kidney. My dad’s creatinine level fluctuates from the ranges 1.6 to 2.2 over the two months. Sometimes, it had 3.1 and retreat into 2.1. Still it has been consistency in around 2.0, 2.1 and 2.2. Is there any possibility of normal creatinine level after removing stones
Hi Subodh, It sounds like the left kidney is obstructed and has been damaged by obstruction. Likewise he has some scarring of his right kidney and that accounts for serious reduction of overall kidney function. Removal of the obstructing stones is critical. I do not think kidney function will return to normal so much as it may stabilize. The real risk is progression to kidney failure with need for dialysis. Prevention of more stones is crucial, so you need to know what the stones are made of and why they form. Regards, Fred Coe
Happy to see you
Hi, I presume your serum creatinine has risen, and assume that is from the PNL. The main thing is for your urologist to be sure no obstruction remains. Possibly kidney function will improve. But if there is obstruction, a kidney can be damaged or even lost. So, be sure your urologist is maintaining normal drainage. Regards, Fred Coe
Hi Doctor!
I am 22 and have been having kidney stones for about 6 to 7 years. I usually have about 2 to 3 stones on each of about 3 mm to 4 mm in size every time I take an ultrasound. I had taken homeopathy medicine and it reduced the frequency of pain and number of stones. However, once stopped my body keep’s producing stones.
Does having kidney stones for several years cause damage to the kidney? Am I in risk of CKD?
Also with regards to the COVID-19 virus, is my condition considered as an “underlying disease” and therefore worsen the risks of fighting the virus?
Your advice on this will be greatly appreciated. Much thanks!
Kind Regards,
Dias
Hi Dias, Kidney stones can gradually damage kidneys but usually not so early in life. I would suggest you consider regular medical prevention – here is a good article to consider. As for Covid, you are not at high risk unless your kidney function is importantly reduced, and your physicians can tell that from routine blood tests. Regards, Fred Coe
Thank you Doctor for your reply and information. I will keep that in mind.
Could there be a patient who has slightly lowered kidney function to significantly lowered kidney function, that show no to less symptoms?
I am not able to get any tests done, as doctors recommend that I stay away from hospitals unless extremely urgent. Therefore, I am also not going to work these days.
Thanks & Regards
Hi Dias, Mild reductions of kidney function cause no symptoms and if present the matter can wait until the epidemic is over. Regards, Fred Coe
Once again, thank you very much for your time and information! 🙂
Tc
I’m a 70 year old female with a 1.2 cm and an 8mm kidney stones. My last blood test showed an elevated bun/creating ratio. In fact, every blood test I have always has an elevated ratio for years. Should these stones be surgically removed or left alone until they present with a problem? I also have been treated with high blood pressure for 19 years. I have moderate peripheral neuropathy and have been experiencing very low body temperature when up doing light housework, such as 95.5 or lower . Any advice would be greatly appreciated.
Hi Bobbye, Sorry to be so late. High BUN to creatinine ratios usually reflect either increase in protein breakdown to urea – common cause is steroid use or high protein diet, or diuretics that favor urea reabsorption – perhaps a blood pressure treatment. Low body temperatures can reflect hypothyroidism and that can also possibly raise the BUN/creatinine ratio, but I doubt that is your issue. I would guess it is a diuretic. As for symptomless non obstructing stones, in general I leave them alone but your urologist needs to make the decision as I have not seen your CT scans and am not in a position to make a recommendation for you. Regards, Fred Coe
Hello my mother is 55 years old and just got her gfr back and it is 49 and creatine was 1.24. She has lupus but she also has a 1mm kidney stone. She has been having lower back pain recently. 3 months ago her creatine was normal and her gfr was 86. How did it drop so fast? Should I be worried?
Hi Emily, This reduced kidney function is most likely from her Lupus or some other cause than her 1 mm stone unless the stone is obstructing a kidney. The matter is of high importance and I do not have enough information to make any useful statement except that her physicians need to figure out the cause right away and make some appropriate treatment plan. Regards, Fred Coe
Sir My age is 24 male and my creatinine level was 1.16 and increase to 1.18 in 6 months and i used to take high protien diet and creatine supplemnt while doing gym . Since 6 months i left gym but still it increased to 1.18 . May i know is there any damage or problem in my kidney ?
I have kidney stones in both kidney 4mm also
Hi Himanshu, You should be evaluated as to the cause of the stones, which depends on serum and 24 hour urine testing and will also provide information about your kidney function. Here is a good starting article. Regards, Fred Coe
Hi Hiamsnhu, The change in creatinine is trivial. The high value may well be large muscle mass. I doubt it is kidney disease. Your physician could collect a 24 hour urine for creatinine – made by muscle – and see if the creatinine clearance is reduced – I suspect it is high. Regards, Fred Coe
I have been dealing with chronic kidney stones for 6 years now. I have calcium oxalate stones and have severe kidney pain on left kidney only. I have been diagnosed with hypercalciuria. I am curious as to what other tests should be done? I have gotten no answers and am a 36 year old female. I cannot live like this and would greatly appreciate answers.
Hi Vanessa, if you have calcium oxalate stones and genetic hypercalciuria as a sole diagnosis, here is a very good article on treatment. The main first step is diet change, and this article focuses only on the main diet elements. Bone an lose mineral in hypercalciuria, so be sure and get a bone mineral scan to be sure where you are. Regards, Fred Coe
Get your PTH levels checked. You could have hyperparathyroidism.
I found out through a CT scan (for unrelated reasons) I have a 5mm kidney stone. A six month re-check shows the stone as 6mm with an additional 1mm stone. My GFR was 91 in 2018 and then dropped to 67 a little over one year later. Is this a significant decrease and could it be related to the kidney stones, which by the way, have caused me no problems. I was scheduled to have lithotripsy but then Covid-19 happened and that was cancelled. I’m just worried I may permanent kidney damage because of these stones.
Hi Linda, The single stone found on CT is not likely to reduce kidney function so much in one year. As for lithotripsy, you do not provide any reason for it – pain, bleeding, infection, obstruction. In general without some reason one does not do anything about an incidental stone. I would focus on what caused the fall in function – lab error, medications? Regards, Fred Coe
In March my GFR was 44 ,and In August it was 46 . I have a 1cm stone on my right kidney . Is that the main reason for my low GFR ?
Hi Lulu, My worry is that the stone might be obstructing the right kidney and lowering its function. Be sure your physician has ruled out that rather bad possibility. If there is no obstruction, then you have some kind of kidney problem that your physicians need to understand and treat, Regards, Fred Coe
I am sorry for my typo , in July it was 46 .
For the past 5 years my GFR has been hovering slightly above or slightly below 60. I am 56 years old, 187 lbs and have a fairly large muscle mass due to weight training since my teens. I have also been on a PPI for GERD for more than 30 years. I was diagnosed with hypertension at the same time as the GFR issues were discovered. It is well controlled now with appropriate medication. Having spent my life dedicated to being strong and healthy my GFR scores worry me and I want to know WHAT is causing low GFR- whether it is PPI , stone or other factors. Is this an unreasonable request of my primary care physician?
Hi Mark, the eGFR is a poor estimate at best. Muscle makes creatinine and delivers it into the serum like water from the faucet into a bathtub, kidneys filter creatinine out of serum like the drain; the height of the water – the serum creatinine – depends on the balance between faucet and drain. The eGFR regression compared actual filtration to serum creatinine over a range of people. Those with the largest muscle mass will have a lower eGFR from the calculation. Ask your physician if a 24 hour urine for creatinine might be useful – yours may be very high and the ‘GFR’ estimate faulty. Regards, Fred oe
Thank you so much Doctor!
Dr Coe
My latest blood work shows GFR “stable” at 56 and creatinine at 121. I am in denial about early kidney disease I guess. My doctor didn’t think the 24 hr urine creatinine was necessary because past 3 years creatinine has been 121 along with below normal
GFR. Any further suggestions would be appreciated.
Hi Mark, Given reduced filtration as judged from your serum creatinine, your physicians need to determine why and what if anything can be done. The main urine test here is protein and or albumin which is high points to one class of kidney disease, and if normal to another. Regards, Fred Coe
I had a blood chem last may and my creatine is 1.6. I had a kidney stuck in the ureter so i had eswl. After three months my creatine is 1.4 but my egfr is 58. But upon KUB they found 1 stone in the lower right of the kidney. 3mm. Should i be concerned that my egfr is only 58?
Hi Edmund, I fear the stone obstructed the kidney and damaged it. Your physician will know from CT scans. If so that is unfortunate and cannot be undone. The main concern in prevention of more stones. Regards, Fred Coe
Hi! My creatinine level as per lab result is 0.98. But my urine discharge is irregular. Can I have your expert opinion on this? Thanks in advance.
Hi Vhal, The single value is not interpretable without age and sex. Urine volume is unrelated to kidney function. I cannot say more without more information. Regards, Fred Coe
Hi Dr. Coe,
Thank you for the article and the comments board.
CT confirmed a 5 mm right side hydoxyapatite stone at the right UVJ, partial obstruction causing moderate right renal hydronephrosis and hydroureter to UVJ.
It’s been 6 weeks since symptoms first appeared (the stone could have been in my ureter longer than that). Only had 3 renal colic episodes but long ones (4 hours about 5 weeks ago, 7 hours about a week ago, and the most recent 36 hours).
What concerns me is the high Creatinine of 148 UMOL/L (reference range 44-110) and high Neutrophil 8.10 x10E9/L (reference range 44-110). 2 years ago, my Creatinine was 76 UMOL/L and Neutrophil was 5.60 x10E9/L. I have no BP, cholesterol, and diabetes issues. I’m in my mid 40s There are some smaller than 3mm stones within my left kidney.
Is this considered AKI? Could I end up with CKD? Can my Creatinine come back to where it was once the obstruction is removed? How urgently does the stone needs to be removed? I’m surprised that I’ve been discharged from ER, and urologist is in no rush to see me. Thank you in advance!
Hi Joe, You have had 6 weeks of obstruction and your serum creatinine has risen significantly. I suspect the obstructed kidney is not functioning well so your other kidney must provide importantly to your overall kidney function. The higher neutrophil count could reflect infection behind the obstruction. While AUA guidelines permit obstruction up to 6 weeks, some evidence suggests kidney damage may occur earlier.I would mention your concerns to your urologist. A renal scan could reveal the degree of injury to the obstructed kidney. Your urologist is entirely responsible for your care, of course, and certainly aims to protect your kidney from harm. Regards, Fred Coe
Hello! I have had a stent placement recently, and my GFR was low. I see a kidney specialist and he was telling me that if it kept up low I’d be on dialysis very very soon.
I’ve never had kidney stones and required a procedure to help with it till this past week.
Hi Rika, Perhaps the kidney with the stent is the better of the two, and when the stent is out your overall function will improve. Possibly you have chronic kidney disease and the one stone causes an acute fall in function. As I do not know any details of your situation, I cannot offer more. But since this is your first stone and it occurred with severe loss of kidney function your physician might want to measure your 24 hour urine oxalate excretion. Regards, Fred Coe
I would like to know who painted this kidney art at the top of the page?
The work is by a Chinese artist. Details are at the beginning of the article along with a link to his site. Fred
What about a calcium stone 8mm non obstructive causing pain with a GFR of 44… taken 3 times in. 55, 45, 44. Could it improve GFR?
Hi Gayle, You seem to have reduced eGFR yet stones are not obstructing. The reduced eGFR is a worry and given stones obstruction an obvious cause. I would be sure your kidney(s) are not obstructed. If stones are not the cause of the low eGFR something else is and your physicians need to figure out what that is and try to correct things. Regards, Fred Coe
I has a stone block my left ureter with some additional stone up high. I had a stent and lithotripsy and the obstructing stoned is mostly gone. Need another lithotripsy for remaining stones. I have a staghorn stone in my right kidney that will be taken out through my back when we are done with the let kidney. bun 31, creat2.28 and egr27 before the procedure. 4 weeks after procedure little improvement, do i have kidney disease or failure and how much improvement should i hope for
Hi Susan, I suspect that your large stones plus perhaps infection have caused some kidney damage. It is important for you to have a nephrologist as part of your medical team, and strongly suggest you arrange for that as soon as possible. That kind of physician is ideally trained to help preserve your kidney function. Regards, Fred Coe
Can eGFR fluctuate? In the past I’ve been 101-117. September 2020 i was 117 and now my recent results taken 2 days ago show im at 99. I do have stone pain and ive had stones many times in the past but I’ve never seen it lower my eGFR.
Hi Lilith, Yes, eGFR can vary, especially within the normal range as yours does. Stone passage, surgery both can reduce function which usually comes back up within weeks. If it does not, your urologist will know to search for possible obstruction. Regards, Fred Coe
Hi my mom had 4 mm kidney stone left proximal ureter..had mild hydronephrosis at time of diagnosis 5-7 days after it passed ( or we think it did , my mom felt the pain move down ).. we redrew blood gfr was 38 creat 1.5 bun normal . Can my mom gfr get back to normal .. she was normal before this stone . I’m heartbroken
Hi Mary t, Obstruction lowers kidney function, so I would hope with time the kidney will improve. My question is whether the stone passed or not? Is the kidney still obstructed. Her physician can tell, and fix things if needed. Regards, Fred Coe
I am 37 years old and I was diagnosed with CKD Stage 3 April 2020. My eGFR was about 54 found out in October 2020 that that I have a kidney stone in both kidneys. I had to go to the emergency room in November as my blood pressure rose to 168 over 106 and a eGFR of 40. Could the stones be getting bigger causing more obstruction or could I have already had kidney disease prior to the renal stones?
Hi Adrian, If the stones are obstructing your kidneys or are infected they could be reducing your kidney function – your urologist can determine this. Possibly you have hypertension as a primary disease that is injuring your kidneys, and your personal physician or a nephrologist would be able to determine it. Obstruction lowers kidney function. Stones associate with high blood pressure. This is why one needs to treat patients, not stones. I suspect you have treatable diseases, but you need your physicians to help – a lot. Regards, Fred Coe
My father’s age is 47.his serum creatinine level is 2.1 and renal stone 13mm .what i have to do next? Is there any problem?
Hi Saad, Your father has considerable loss of kidney function. His urologist needs to be sure the stone is not obstructing a kidney. He needs to be seen by a nephrologist as well to determine if there is an intrinsic kidney disease. Stone prevention comes after the loss of function is remedied. Here is a good start on that. Regards, Fred Coe
I have right kidney stone since 1999. 1999 it was operated with lathrotopics methods. Since 2009 I could not find any issue . In 2009 again it started painting . This time it was operated with PCNl method . Next 9 year (since 2018) I was not having pain. But again it started at mid of 2018. In July I had operated with stent ..as doctor told me that pain was not happening due to stone. Stent was removed after 40 days . Now i have lots of pain . I am taking pain killers. My right kidney GFR shows only 6.71. doctor gave me two options ..1. nephrotomy 2. Stone removal and do the follow-up .kindly advise me what should I do now
Hi Poonam, It sounds like your right kidney was damaged by stones and the inevitable effects of surgeries, and is no longer functioning well. Removal is a reasonable option. It possible I would suggest a second opinion at a specialized center just to be sure the kidney cannot be salvaged. Regards, Fred Coe
I’m a 47 year old female and found out I had a 4mm kidney stone when getting an ultrasound as just check up, nothing specific. The stone has not moved in 3 years. For the past 2 years my eGFR was at 100. This year during my annual blood test, my eGFR came back as 60 and my creatinine is at 1.097. I haven’t noticed any major issues in health, except 3 days before the blood test I pulled a back muscle and two days before the test I took an Aleve. I am now worried I have Stage 3 kidney disease. Is it possible that the stone has suddenly causing issues?
Hi Jay, I would repeat the test. NSAIDS can reduce renal function reversibly as part of their normal action. If the increase in creatinine is persistent it warrants consultation with a nephrologist. The US is interesting – what were they looking for??? Regards, Fred Coe
Dr. Coe, Thank you for your very informative articles. I am a 54 yr old male, and had my first stone at age 26. Five years ago, I started taking verapamil to prevent headaches. In the past 18 months, I have been passing many larger (4-6 mm), smooth stones. Do you think the verapamil may be causing them, or may actually be helping? Info I have seen on the internet is very confusing. Thank you.
Hi Bill, Verapamil is indeed a front line drug for migraine headache. I know of no role in kidney stones. I do suggest repeating your serum and 24 hour urine studies to see why more stones form. There usually is a clear reason why. The stones sound like phosphate being smooth and round. Get them analyzed. Regards, Fred Coe