Kidney Stones, Kidney Function, Kidney Disease

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.

117 Responses to “Kidney Stones, Kidney Function, Kidney Disease”

  1. Andre Justice

    Hello. I’ve had what has felt like kidney pain for about 2 yrs in both kidneys but more intense in my right. Kidney stones are prominent in my family. Last year my eGFR was 90 with all other levels normal. About 6 months ago the kidney pain seemed to become more frequent. About a month ago my eGFR dropped and has teetered from 49-60(s) since with repeated blood tests. High creatinine, high BUN high triglycerides. But I don’t consume anything to present such results. I’m currently experiencing my first Kidney Stone diagnosed as R ureterolithiasis. It has been the most painful thing I’ve experienced and I have been through severe appendicitis with appendectomy. Based on my eGFR dropping prior to the kidney stone presenting itself- could this be signs of true Chronic Kidney Disease or just side effects of the kidney stone forming itself? Also, does ureterolithiasis simply indicate a stone in the ureter or that its actually stuck in the ureter?

    Reply
    • Fredric L Coe

      Hi Andre, Your eGFR could have fallen because of a stone obstructing one ureter, and if so it should rise after the stone is passed or removed. If it does not rise and you have no signs of obstruction your physicians need to figure out the cause and help improve matters. Regards, Fred Coe

      Reply
  2. Lisa Morris

    Hello, I am 50 y. o Caucasian F. I have had small kidney stones here and there on and off since age 20. Have passed them all no issues and have gone years with no stone formation. However in the last 3 years I have formed 2 stones that were 6 to 7 mm and needed to be removed. The last stone dropped my egfrs to 88.. and 102. Creatine . 78 bun 15 albumin 4.5..blood pressure 112/68. Should I expect my egfr to raise up again into the 90s now that the stone has just been removed? And how long generally speaking will it take to raise back into the 90s

    Reply
  3. Dan

    I just had a really fun trip to the hospital because of what was found a kidney stone. I would not like to repeat this. I am 50, in excellent shape. Hight Weight proportional. Nearly obsessive about my diet, exercise regularly. Don’t eat red meat. Blood pressure is normal. I have been taking Creatine for about a year. Plus I have recently added Spinach to my diet. I know spinach is massively high in oxalates. What are you quick thoughts on Creatine & Spinach relative to Kidney Stones?

    Reply
    • Fredric L Coe

      Hi Dan, my quick thought is just like yours. But having had a stone I would check out my serum and 24 hour urine results to be sure there is nothing lurking. The oxalate should be gone – you certainly are no longer oxalate loading. As for creatine, a quick search in PubMed under ‘Creatine supplements AND kidney stones’ turned up no relevant papers. Regards, Fred Coe

      Reply
  4. George A.

    Hi,
    I have recently been diagnosed with having a calculus of size 9mm, in lower left calyx of my kidney. Over the past 2 months my E-GFR has declined from 61 to 42 only. But a year back it was normal at 94. I am 60 and have high blood pressure since past 10 years. Apart from that all my reports are mostly within normal range.
    Is the presence of stone causing reduced kidney function ? Will the removal of stones improve my kidney function ? Which stone removing procedure would be better in my case ?
    Thanks in advance.
    Harry

    Reply
    • George A.

      Addendum:
      My Blood pressure is within control, as I take daily medicines for that. About 4 months I did have urinary infection, for which I was prescribed antibiotics (It got cured after taking the medicines).

      Reply
    • Fredric L Coe

      Hi George (It may be Harry), the decline in gfr is worrisome. I would be concerned about primary hyperoxaluria that can present with stones in later life and cause kidney disease. Be sure your physicians have considered this possibility. Another possibility is primary hyperparathyroidism, but it is not so likely to cause kidney function loss. Obstruction of a kidney will do all this, but I cannot imagine that it would go unnoticed. Even so, be sure your physicians are satisfied it is not present. Finally, I am sure your physician has inspected all of your meds as causes of the reduced function, an essential step. I would be concerned, very much so. Regards, Fred Coe

      Reply
  5. Kumar

    HI I was diagnosed with a proximal ureter stone and some small stones , at that time my creatnine level was 1.54, I got Cytoscopy with DJ stent treatment done , then I got lythotripsy done then got stent remove, but my doctor never said about createnine level and kidney damage. Should I worry or can I trust him , he said I am young its not big problem , but wherever I am reading it says 1.54 creatnin is not good.

    Reply
    • Fredric L Coe

      Hi Kumar, You are right. Get the test repeated. Kidney function may have fallen because of surgery, and should be normal by now. If not, get a nephrologist to take a look. Do not fail to do this as there are real dangers when kidney function falls in a stone former. Regards, Fred Coe

      Reply
  6. Stacy

    I have had kidney stones (calcium) for several years and have had them removed multiple times. My urinalysis always shows the albumin/creatinine ratio is high. 409 this last time. All my other kidney functions are fine. I am not diabetic or have high blood pressure. My urologist and primary care doctors don’t seem to be too concerned. Is it “normal” to have that high of a result with kidney stones??

    Reply
    • Fredric L Coe

      Hi Stacy, That is a high ratio but could reflect blood in the urine from stones. Check of the urine was screened by dipstick for blood or not. If not, get the test done on a sample that is clearly negative for blood. If in that urine you have so high a urine albumin something is wrong and it is not at all normal. I bet it is simply blood but be sure! Regards, Fred Coe

      Reply
    • Jazzmin M Wegley

      Let me tell you this you’re urologist and Doctor don’t seem that worried about it because they are not they make money out of your pain. I just passed a 2 inch by 3/4 of an inch kidney stone yesterday by myself with the help of two prescriptions Diclofenac and tamsulosin also Azo max strength and a friend of mine gave me some kind of muscle relaxer. I drank as much water as I could stomach. not to mention apple cider vinegar the night before and lots of lemon juice the previous day’s. And then I started to push from my kidneys. Like the worst feeling that you had to go pee ever. And that didn’t work so I jumped in a bath 3″ deep hot water then that I started out in cold and I noticed that my kidneys started to tense up tighten up. So I got out of the bath and I drink some more water and I let some of the urine flow. Then I drank a whole bunch more water. and I noticed my heart was beating hard and that my head was starting to feel funny and then I ran my hands under hot water and I noticed that the pressure started to come and I thought back to giving birth to my son. I remembered my mom saying something about the tips of her fingers going numb from burning them in the hot water was so hot that I got used to the hot but thinking back to my son think learn I remember the nurses telling me to breathe to push but to breathe and they said “pressure! pressure!! Breathe! breathe! No honey don’t hold your breath you’ll pass out! push! come on you got this, push! Breathe honey, good job! keep pushing! pressure! pressure! breathe! THERE WE GO!!!” Thinking back to that while having that kidney stone pass helps me a lot and I prayed to God that I wouldn’t get through it. So I just reminded myself to breathe and to push in to breathe and I was looking at myself in the mirror and I saw my eye go sideways and I realized that when I thought I was going to pass out before it was because I was in so much pain that may I was going sideways so my vision was blurry but I was holding my breath and if I had not holding my breath and just went through and just kept pushing through that pain then possibly would have been able to pass the stones sooner. I took my life into my own hands and I hope that I can continue to be strong and to be brave and to not let my fear stop me from pushing the rest of the stones out!! that was the biggest thing is cuz I was scared I was afraid of the pain I was afraid of what the kitty Stone could do to me but honestly it pushing it out it’s a lot less damaging than leaving it in so keeping my fingers in hot water and elevating my blood temperature raise my blood pressure without having that much actual pressure building in my heart or my brain and I just pushed the stones out I cannot believe it that stone is the same size as my thumb and I pushed it out by myself without the help of medical professionals. that urologist told me that I was imagining things and that there was nothing to worry about and that he got the stones out of my kidney and that the small fragments that were left would pass on their own.. judging off the size of the kidney stones I’m saying that they were never going to pass and I know that he saw them while he was in there with that camera and I know that he did not tell me about them and he did not want to use dye to help a CT scan see more clearly.. I was probably really close to having a heart attack or a stroke or dying probably of kidney failure or a heart attack or stroke.. taking my life into my own hands was probably the greatest thing I ever did.. I’m sitting here wondering if I should do that doctor for not telling me that he saw all those stones in my kidney. I really could have died and I’m only 25 years old and I told him that I felt like I was going to have a heart attack or something and he said that I was too young for that to happen. and he said last words were come back and see me if they keep bothering you..

      Reply
      • Fredric L Coe

        Hi Jazzmin, Stone passage is horrid as you describe. Unlike delivery pushing will not help, but whatever you did by way of pain control is fine. I gather you have ureteroscopy and your physician removed stones or perhaps pulverized them into dust using a laser. As for retained stones, I would ask her/him was is in your kidneys and perhaps have a post operative ultra low dose CT to count what is there as a baseline for prevention. Prevention of more stones is crucial to stave off more attacks. Here is a good place to start. Regards, Fred Coe

        Reply
      • Steve

        My kidney gfr was found to be 51 by chance as i was being tested for autoimmune diseases. Kidney stones were discovered on a lung ct scan but deemed unobstructive. I was diagnosed with sjogrens syndrome, lupus, and anca related Vasculitis. Sudden severe pain sent me to hospital one night. Gfr at 47. Ct scan showed kidney stone obstruction. Had 4 stones removed and gfr jumped back to 74. Doctors tell me Sjogrens causes renal tubular acidosis and that my kidneys weren’t really damaged just impaired by the acidosis. My bloodwork was mostly normal other than high chloride and low albumin consistently. My question is should i take potassium citrate or sodium bicarbonate to balance or reduce the chloride? And will apple cider vinegar dissolve almost purely calcium phosphate stones?

        Reply
        • Fredric L Coe

          Hi Steve, Your stones are almost purely calcium phosphate, blood chloride is high, CO2 was not mentioned but is probably a bit low, urine pH is high – the stones tell you that – and RTA from Sjogren is a fine idea. Yes, potassium citrate is good if it will raise urine citrate – surely very low – and not raise urine pH so much that calcium phosphate supersaturation actually rises. So 24 hour urines are crucial for monitoring. Your condition requires expert medical management given vasculitis and reduced kidney function. A nephrologist will special training or experience with sjogren is ideal here. Regards, Fred Coe

          Reply
  7. Charmaine roberts

    Hi i had a stag horn kidney stone about 5yrs ago. I had it removed but they couldnt get 1 piece out. Since then ive had alot of uti infections and the past year im getting alot of pain in my back and are tired all the time. I do have a xray yearly to make sure it hasnt grown

    Reply
    • Fredric L Coe

      Hi Charmaine, Possibly the stone fragment is infected and promoting UTI episodes. Your physicians can tell, and if it is perhaps it is time to remove what is left. Regards, Fred Coe

      Reply
  8. Shivam

    Is have stone in my right kidney of 3mm . Is it risky and does it affect to my kidney

    Reply
  9. Katie

    Hi,

    I have a long history of stones (18 years), no high blood pressure, but I am overweight. Recently I had a total of 8 stones removed, some that were small enough that I could have passed them, and some I could not. My eGFR has been steadily declining for over a year, but my PCP never mentioned that it could have anything to do with the stones. My urologist has scheduled further testing in an attempt to figure out what is causing the stones and how to prevent them. Is it possible that my kidney function could improve if I am no longer plagued by stones? Or is stopping decline the best I can hope for?

    Reply
    • Fredric L Coe

      Hi Katie, Is is possible your urine oxalate excretion is high?? I would presume it has been measured repeatedly, but just in case. Of course, your urologist will make sure about any obstruction from stones. Are you possibly diabetic? Does your urine contain an excess of albumin? Your physicians need to look into all this, and find ways to halt further progression. Regards, Fred Coe

      Reply
  10. hari

    i brother have stone in his kidney now only he remove it and then my question is does it effect kidney function after removing

    Reply
    • Frederic L Coe

      Hi Hari, usually stone surgery does not affect kidney function. If the stone is obstructing, removing it will improve function. Regards, Fred Coe

      Reply

Leave a Reply