Jeff, a reader of this site, suggested this topic and I realized it was one that I should have written long ago.
You can make sense of all those numbers in the 24 hour kidney stone reports.
You can use those numbers to understand how things stand with you.
Reading the numbers can help you achieve your best possible chance at stone prevention – which is the only reason all those lab tests were done in the first place.
This article deals with calcium stones. A second one will cover uric acid stones.
Be Sure You Have Been Screened For Systemic Diseases
Your physician does this part. But even for systemic diseases stone risk is gauged in the urine so you can read along and assess how prevention is going.
Units of 24 hour Urine Measurements
Time
Because excretions of stone risk factors are in amount per 24 hours, we need the time of the collection. You provide the beginning and end times for the collection, in minutes and hours, and the laboratory corrects all excretion values to amounts in 24 hours.
For example, you start a urine collection at 7 am and complete it at 5 am the next morning. The measured total time is 22 hours. If the volume is 1.5 liters, the volume ‘corrected’ to 24 hours is 1.5 liters x 24 /22 (1.09) or 1.636 liters/24 hours.
It is obvious that the less ‘correcting’ the better, because the ‘correction’ assumes that every hour is the same as every other hour, which is not likely. So you want to collect as close to 24 hours as possible. If your time is below 22 or above 26 hours throw it away – no cost – and do another.
I am sure this is an unnecessary comment but sometimes people forget that a urine collection begins by emptying the bladder, writing down the time, and discarding the urine. Here and there people add it, making the real collection from whenever the bladder had last been emptied.
Volume per 24 Hours
Urine volume is measured in liters (L) or milliliters (ml). A milliliter is 1/1,000 of a liter, so there are 1,000 ml in a liter. One liter is 1.06 quarts. The laboratory measures the total volume of urine if you send or bring it. Often you will read the volume yourself, off of a collection container.
Because excretion rates like calcium, oxalate, citrate, and uric acid are calculated by multiplying their concentrations by the 24 hour volume, mistakes in timing, collection, or measurement of volume will make the results less valid. You provide the collection times, assure all the urine has been collected, and even may measure the volume, so quality is under your control.
Excretion Rates
Urine creatinine, calcium, oxalate, phosphate, and citrate excretions, are in milligrams (mg) or grams (gm) per 24 hours. A mg is 1/1,000 of a gram. An ounce contains 28.3 gm.
Urine sodium is measured in millimoles (mmol) or milliequivalents (mEq)/24 hours. Atoms, like sodium, each have a weight made up mainly of their constituent protons and neutrons. One mmol of sodium is 23 mg.
Some atoms like calcium have two charged sites which can bind to other molecules or atoms. They are often measured in milliequivalents (mEq) which is the weight times the number of sites. Sodium has only one, so mmol and mEq are the same.
Molecules like creatinine and oxalate have weights made up of their constituent atoms.
Conversion of Units
Some laboratories report in mmol or mEq. You can convert your lab report if it differs from mine. I will be using L for urine volume, mg for urine creatinine, calcium, oxalate, and citrate, and mmol for urine sodium. Here are the conversions:
Creatinine; 113 mg/mmol
Calcium: 40 mg/mmol; 20 mg/mEq
Sodium: 23 mg/mmol or mEq
Oxalate (oxalic acid): 88 mg/mmol; 44 mg/mEq
Citrate (citric acid): 189 mg/mmol
Direct Measurements
Acidity or alkalinity are measured in pH – no units. It is a logarithm to the base 10 so a change from 6 to 5 means a 10 fold increase in acidity, from 6 to 7 a ten fold increase in alkalinity.
Supersaturations are calculated from urine concentrations. The one we use here is the ratio of the concentration dissolved in urine of each of the three important stone forming salts, calcium oxalate, calcium phosphate, and uric acid divided by their individual solubilities at body temperature. Values below 1 mean crystals will dissolve. Values at one mean crystals will neither grow nor shrink nor form. Values above 1 mean crystals can form and grow. Being a ratio it has no units.
Is The 24 Hour Urine Valid?
Urine creatinine
Like all 24 hour excretion rates, that for creatinine is calculated from the concentration, measured volume, and collection time.
Because muscle cells make almost all the creatinine lost in urine any two urines you collect will have about the same amount of creatinine in them. A more than 20% variation between two urines suggests an error in one collection. If there are many collections, most creatinine excretions will line up pretty well, and an outlier – too high or low by more than 20% of the average for all the collections will stand out.
When a urine stands out as different from prior collections, I say it is best to repeat it. If there are two, use the one that seems more correct.
‘More correct’ is judged by expected amounts of urine creatinine. For men, one expects about 18 – 24 mg/kg body weight; for women, 16 – 22. A urine far out of those ranges is suspect. In people who have a high body fat percentage the ratio can be as low as 12 mg/kg/day, and people who have little body fat and a high muscle mass can be as high as 30 mg/kg/day.
Conditions of Collection
Did you eat and drink as usual, or show off? Had you ‘improved things’ since a recent stone so your collections reflect new habits and not those that led to the stones? Every collection is a one day frame out of a movie that is running 365 frames a year, so if these few days do not reliably represent your average life, their results will inevitably mislead you and your physicians and falsify what you came to do.
Reading the Results
Urine Volume
Curhan and colleagues have linked new onset of stones to urine volume in three large cohorts reviewed in our other articles. Take a look now. The graph is on page 2 of the article. Risk is on the vertical axis, and urine volume is on the horizontal axis. When red shows above the line at 1 it is above normal.
Risk is low above 2.25 liters/24 hours. But the day is long and the 24 hour urine is an average, so for insurance it is best to overshoot so the low times are still not too low. I would say 2.5 – 3 liters liters/24 hours is ideal.
Urine Calcium
Stone risk increases with urine calcium excretion above 200 mg/day in men and women – take a look. The calcium risk is at the upper left corner of the graph.
If you have above 200 mg/24 hours you have ‘hypercalciuria’, a high enough calcium to pose risk of stones – and also bone disease. There are many causes of hypercalciuria. The commonest is simply a genetic tendency, called idiopathic hypercalciuria. ‘Idiopathic’ means your physician has ruled out any of the other causes of hypercalciuria.
You lower urine calcium in idiopathic hypercalciuria with reduced diet sodium, avoidance of sugar loads, and medications if needed. You compare treated to untreated excretion to see how well the treatment worked.
Urine Sodium
Urine sodium is essentially the diet sodium intake. Because urine losses can lag intake when intake varies sharply, urine sodium is a good estimate of the average over 3 – 4 days. If you tried to lower your diet sodium to 100 mmol/24 hours, 2,300 mg intake, and you find 200 mmol/24 hours, you can be sure that your average intake is on average twice what you desired.
Suppose your urine calcium is 250 mg/24 hours, urine sodium 200 mmol/24 hours – twice the upper limit of diet sodium in the US and above the optimal value of 65 mmol (about 1,500 mg/24 hours). You would want to lower your diet sodium. Suppose your urine sodium was already 65 mmol/24 hours and urine calcium was 250 mg/24 hours; you would want to take other steps like thiazide diuretics or potassium citrate.
What if your urine calcium is 450 mg and your urine sodium is 200 mmol? Sounds like a bigger problem, but it is not. When urine calcium is higher the slope dependency of urine calcium on urine sodium is steeper, so the same reduction of sodium could bring urine calcium quite a way down.
If you lowered diet sodium and there is no change, do not assume the test is wrong. Check the creatinine values – do they match? If so, you have not lowered your average sodium intake. Sodium is an atom and you are not a cyclotron; you cannot make sodium or destroy it.
Sugar Loads
Given to people with idiopathic hypercalciuria they cause a rapid rise in urine calcium and supersaturation. The 24 hour urine will tend to underestimate this because of averaging throughout the day.
Thiazide Diuretics and Potassium Citrate
These drugs come after diet changes have not proven sufficient and are added to the diet changes.
Urine Oxalate
Stone risk increases with increasing urine oxalate and if the risk ratio is not as high as for calcium risk appears at very low levels of excretion – above 25 mg/day. In general, high urine oxalate comes from high oxalate diets, low calcium diets, or the combination of high oxalate and low calcium together. Therefore treatment is dietary. Excellent food lists are in this site – linked from the oxalate diet article. Rarely, urine oxalate is raised from a hereditary overproduction state – primary hyperoxaluria. Likewise, bowel diseases can raise urine oxalate. These are complex conditions and diet alone is rarely enough.
If urine oxalate is high and you have corrected both your diet oxalate intake and added significant diet calcium, you may have some form of genetic or acquired oxalate overproduction or an otherwise inapparent intestinal absorption problem.
Urine Citrate
Citrate is a powerful force against calcium stones. It binds calcium in a soluble complex. It interferes with calcium crystal formation and growth. Low urine citrate is a risk factor for new stone onset – bottom left panel of the graph. Above 400 mg daily there is no extra risk of stones in men or women, so ‘hypocitraturia’ means a urine citrate below 400 mg daily.
If you begin taking, as an example, four 10 mEq potassium citrate pills a day – 40 mEq, that extra 40 mEq of potassium should appear in the urine. If it is not there, the pills may not be delivering the medication into the blood from the bowel. The urine pH should rise because citrate imposes an alkali load. If it does not and the urine potassium does rise, you may need more of the medication.
Urine ammonia – I will cover this in the second half of this two part article – is a major way the body removes acid, so when you take citrate ammonia excretion should fall. If it does not fall, and urine potassium rises perhaps your pills are potassium chloride – the pharmacist switched from what was prescribed.
Strangely, the urine citrate itself does not rise in everyone even when potassium and pH rise and ammonia falls.
Urine pH
A low value – below 5.5 poses a risk of uric acid stones. A high value, above 6.2 raises calcium phosphate supersaturation and risk of calcium phosphate stones. Potassium citrate can raise urine pH; there are no medications to lower urine pH except methionine and ammonium chloride and these are not usable for stone prevention because they will increase urine calcium and pose a risk of bone mineral loss.
Urine Supersaturations
Get Them
If there are no supersaturations, ask that your samples be processed by a vendor that provides them. Supersaturation is the driving force for crystal formation and growth, and invaluable for monitoring stone prevention.
Relate Them To Your Stone Crystals
There will be three supersaturations: Calcium oxalate, calcium phosphate, and uric acid. Inspect the ones related to your stone crystals. For calcium oxalate both calcium oxalate and calcium phosphate supersaturations matter. If calcium phosphate, that one matters most. If pure uric acid, it is uric acid supersaturation.
Reduce Them
One should not compare values in a stone former to values in normal people, who often have urine supersaturations as high or higher than those of stone formers. Active stone formation means supersaturation is too high for you whatever the value may be and needs to be lower. You reduce your supersaturations by increasing urine volume and reducing excretions of calcium and oxalate, or raising excretion of citrate without undue increase of urine pH. That is why we make these measurements.
Compare Then to Now
Compare you now to you before your most recent fluid and diet intakes or medications: If they have fallen, things are going well; if they have risen things are not going well. If stones are still forming, supersaturations need to be lower. If there have been no more stones and supersaturations are stable, stand pat. If supersaturations are below 1 and stones are still forming, the urine samples do not properly represent your real life.
A Good Schedule
When? I like two 24 hour urines before treatment – it gives a sense of averages. After treatment has begun – diet changes, fluid goals, lifestyle, it is important to get another. The timing is up to patients: You know when something has changed, or ought to have changed, and need to be sure it has indeed changed in the right direction. It goes on like that until treatment is reaching its goals – lowering supersaturation by at least half – after which once a year is a good idea.
Thank you for your awesome site and resources. After suffering stones for a while, my Dr finally after bugging, sent me for a stone analysis and 24 urine collection. Here are my results.
Stone type: Calcium Oxalate Dihydrate / Calcium Phosphate mixed
I did 3 days of urine testing (way it’s done in my Province, 1 jug is no additive, 1 has HCL, 1 has NAOH) My volumes for the 3 days were 2.3L, 3.6L, 2.6L
Creatinine 7.1 mmol/L
Urate 1.5 mmol/L
Creatinine 5.8 mmol/L (day 2 jug)
Oxalate 115 umol/L
Creatinine 4.4 mmol/L (day 3 jug)
Magnesium 1.5 mmol/L
Calcium 1.76 mmol/L
I still have to go for blood work, but at least after a year of suffering, I have the ball rolling. I currently have 13 stones between both kidneys, ranging from 3mm to 13mm. I’m making them frequently, so I’m hoping these urine results can shed some light on what’s going on.
Phosphate 6.95 mmol/L (THIS IS MARKED AS LOW VALUE)
Citrate 1.25 mmol/L
Hi Jay, I would like to help but the data seem fragmented. Perhaps you could post one urine with its volume, calcium, creatinine, citrate and pH so I could look at an ensemble. If you have 2 with complete data so much the better. Isolated values are very hard to interpret. Likewise, pH and calcium and need to be in the same place as you have enough phosphate in your stones to worry about that pH dependent phase. Regards, Fred
Dr. Coe,
I recently had my first kidney stone (around 7mm), which I passed about 2 weeks after diagnosis. My brother and multiple family members also have a history of kidney stones. The urologist sent my stone for analysis, had me complete a 24 hour urine and referred me to renal clinic (I also have a history of vesicoureteral reflux as a child on the side where the stone was located). CT at the time I presented with kidney stone to the ER showed moderately severe hydronephrosis and the urology fellow on call mentioned that my renal parenchyma was low on that side but he didn’t seem super concerned about it (my mother has since told me that my left kidney was noted to be smaller than the right when I was worked up as a child). The results of stone analysis and 24 hour urine are below. I realize that I need to drink more water which I will start to focus on but wondering any other recs based on this profile. I won’t be seen in the renal clinic until early Sept. but would like to start making any recommended modifications. I also have a diagnosis of ulcerative colitis. I am in my mid 40s, around 5’1″ and around 105 pounds.
COMPONENT 1 (CALCULUS): Calcium Oxalate Dihydrate (Weddellite) 30%
Calcium Oxalate Monohydrate (Whewellite) 35%
Carbonate Apatite (Dahllite) 35%
24 hr Urine:
PH, URINE 6.8 QUEST REF LAB
CALCIUM, URINE 195 mg/day
SODIUM URINE 141 mEq/day
POTASSIUM, URINE 33 mEq/day
PHOSPHORUS, URINE 689 mg/day
MAGNESIUM, URINE 51 Low mg/day
SULFATE URINE 10 mmol/day
BRUSHITE 3.55 High
SODIUM URATE 2.25 High
URIC ACID CALC 0.21
TOTAL VOLUME,URORISK 1.43 Low L/day
URORISK OXALATE 19 mg/day
URORISK CREATININE 921 mg/day
CALCIUM OXALATE 1.36
URORISK URIC ACID 386 mg/day
URINE CITRATE 630 mg/day
SUPERSATURATION IN W/RESPECT TO:
BRUSHITE
SODIUM URATE
URIC ACID
Low urine volume
Brushite (Ca phosphate)
Monosodium urate
Dear Cynthia, Your urine is very alkaline – pH 6.8 and you seem to have a high supersaturation with respect to brushite – your stone is 35% calcium phosphate. The low volume is an obvious problem that you can fix out of hand. Your urine calcium is hefty, just below overt increase in stone risk, and in part this is due to your high diet sodium (140 mEq in the urine is the diet intake) so you might want to moderate that to 1500 mg (65 mEq) daily. The stone formed in an injured kidney (smaller) and the urine from that kidney may be even more alkaline, moreover the drainage from that side may be abnormal fostering stones. That is about all I can do to help you without actually knowing your medical condition. Regards, Fred Coe
These are the results from my 24 hour urine collection.
Urine Volume 2.35
SS CaOx 6.79
Urine Calcium 303
Urine Oxalate 31
Urine Citrate 540
SS CaP 0.41
24 Hour Urine ph 5.608
SS Uric Acid 0.85
Urine Uric Acid 0.503
My stones are Calcium Oxalate
Monohydrate 15%
Dihydrate 80%
Hydroxyapatite 5%
I am currently drinking 3 liters of water per day, eating close to 1200 mg of Calcium rich foods, getting up to 1500 mg of sodium and eating under 25 mg of added sugar daily. Is there anything else I should be doing?
Hi Brenda, You are pretty typical of a woman calcium oxalate stone former. Your urine calcium is high enough to pose risk of more stones, and you did not post your urine sodium – is it really 65 mE1 (1500 mg)? If not, get it to be. If that fails, thiazide would be the next step. Regards, Fred Coe
Good Day Dr Coe,
My recent Litholink is very good except for 2 metrics. (My previous Litholink was in Dec 2020):
Mg24 was 182 dropped to 51. Since 2016 the range has been 116 – 182 so this is puzzling.
pH was 5.813 now is high at 6.877
I currently take Pot Citrate 15MEQ 2 tabs twice daily and have been on this dosage for the past year. My pH has done this before. In 2019 under the care of a different doc it went up to 6.782 who over-reduced Pot. Citrate. Since we switched doctors I am confident our current doctor can tweak the Pot Citrate dosage, so am not too concerned about this.
Regarding the drop in Mg24 – I have been taking a Mg supplement as Mg Threonate 3tbs/day each 144mg for the past 4 years – consistent with the prior Litholink. I am also on a thiazide – Indapamide – on a dosage that has been constant for the past 4 years. In fact I have had no Rx changes for the past 1 and 1/2 years.
I would appreciate any thoughts you might have.
In case other metrics might suggest a reason here they are:
Vol 24 – 3.99
SS CaOx – 0.81
Ca 24 – 73
Ox 24 – 28
Cit 24 – 585
SS CaP – 0.34
pH 24 – 6.877
SS UA – 0.04
UA 24 – 0.541
Na 24 – 223
K 24 – 96
Mg 24 – 51
P 24 – 1.006
Nh4 24 – 14
Cl 24 – 205
Sul 24 – 43
UUN 24 – 11.94
PCR – 0.9
Regards
Brent
Hi Brent, thiazide causes magnesium wasting, and you are probably depleted – most magnesium is in cells not blood. Your supplement is too modest – try 400 mf OTC Mg oxide, 1 or 2 a day. Your diet sodium (223 mEq/d) is way too high, a reasonable upper limit is 100 mEq (2300 mg). The high sodium load worsens potassium and magnesium loss. Urine pH rises inevitably with alkali – nothing can be done about it. Your stone risk is low. Regards, Fred Coe
Hi Dr. Coe!
I am currently going through the process to donate one of my kidneys. On my initial visit, a microscopic urinalysis showed a moderate value for Calcium Oxalate Crystals. It was recommended that I complete a 24-hour stone analysis. I am a 41 year old female and do not have a history of stones. It was thought I may have had one 6 years ago, but if I did I was able to pass without knowing it. Below are the results of the 24-hour stone analysis:
Urine Volume: 1.84L
SS CaOx: 6.99
Urine Calcium: 175mg
Urine Oxalate: 31mg
Urine Citrate: 1037mg
SS CaP: 1.13
24 Hour Urine PH: 6.478
SS Uric Acid: 0.16
Urine Uric Acid: 0.377g
The transplant team recommended I go over the results with my PC. My PC suggested that I discontinue the prenatal vitamins and other supplements, and be mindful of foods that are high in calcium and vitamin C. I made the changes (also increased my average water consumption to 2.5-3L perday) and repeated the 24-hour stone analysis 90-days after the initial test. Below are those results:
Urine Volume: 1.82L
SS CaOx: 8.01
Urine Calcium: 381mg
Urine Oxalate: 26mg
Urine Citrate: 1306mg
SS CaP: 1.29
24 Hour Urine PH: 5.864
SS Uric Acid: 0.76
Urine Uric Acid: 0.527g
Needless to say, my numbers did not go in the direction I was anticipating. The transplant team has now recommended that I meet with their kidney stone clinic, but am unable to get in until the end of October. Are you able to provide any recommendations?
Any tips are greatly appreciated!
Thanks!
Lea
Hi Lea, assuming your blood calcium is normal you have idiopathic – genetic – hypercalciuria. Urine calcium is very responsive to diet sodium, and I imagine that went up between the two collections. If I were asked, I would not encourage donation as your urine calcium is quite high, you made obvious crystals and will have only one kidney. Low calcium diet with IH is not good for bones, and bone disease is well described. Likewise, I noticed a very high urine citrate despite a rather low urine pH in the second collection – perhaps your nephrologists might want to ponder that in terms of other health risk factors such as blood lipids, blood pressure, and blood glucose to be sure there are not problems there – I am an outsider, so this is mere suggestions to the wise. Regards, Fred Coe
Hi Dr. Coe,
Thank you for your time. Here’s my 48Hr Litholink report. I had CaOx stones, 49yr, 133lb, exercise 5 days a week. The Day2 collection volume was lower, likely due to it being a day I exercised. The Na 24 was higher on Day2 due to electrolyte consumption I am guessing.
Since both ph and citrate are low, am I a good candidate for Potassium Citrate supplementation? I have since increased my water intake.
Collection Day 1:
Urine Volume – 2.68
SS CaOx (liters/day) – 5.90
Urine Calcium (mg/day) – 372
Urine Oxalate (mg/day) – 35
Urine Citrate (mg/day) – 291
24 Hour Urine pH – 5.288
SS CaP – 0.25
SS Uric Acid – 1.22
Urine Uric Acid (g/day) – 0.544
Collection Day 2:
Urine Volume – 2.15
SS CaOx (liters/day) – 7.01
Urine Calcium (mg/day) – 350
Urine Oxalate (mg/day) – 34
Urine Citrate (mg/day) – 360
24 Hour Urine pH – 5.426
SS CaP – 0.24
SS Uric Acid – 1.24
Urine Uric Acid (g/day) – 0.525
Dietary Factors – Day1, Day2 values (comma separated)
Na 24 – 94, 144
K 24 – 35, 45
Mg 24 – 196, 168
P 24 – 0.971, 0.756
Nh4 24 – 54, 42
Cl 24 – 107, 161
Sul 24 – 53, 47
UUN 24 – 11.93, 9.91
PCR – 1.5, 1.2
Hi snair, Your urine calcium is very high, and a prime issue for your stones. I would not use potassium citrate for fear of converting to calcium phosphate stones, but would suggest higher urine volume – to 3 liters/d as possible – and probably a thiazide diuretic to lower your urine calcium – depending on how much of a problem the stones pose. I presume your serum calcium is normal, and if so you have idiopathic hypercalciuria. If it is even a slight bit high, you could have primary hyperparathyroidism – but I doubt it. Regards, Fred Coe
I’ve had multiple stones mostly when I’ve been pregnant. I have 3 children. I do take potassium cit, citrate 10ml 2 times a day but honestly I always forget at night.
Stone risk factor
Vol: 1.27
SS CaOx: 8.24
Ca 24: 222
Ox 24: 31
Cit 24: 528
SS CaP: 4.66
Ph: 7.1
SS UA: 0.10
Ua 24: 0.779
Dietary factors
Na 24: 161
K 24: 71
Mg 24: 88
P24: 0.896
Nh4 24: 19
Cl 24: 121
Sul 24: 45
UUN 24: 11.90
PCR: 1.4
Normalized values
Cr 24: 1361
Cr 24 kg: 22.7
Ca 24 kg: 3.7
Ca 24/ cr 24 163
Hi Melinda, The fact that most catches my eye is the remarkably low urine volume. So low that stone prevention is impossible. How about more than double? Three liters a day would perhaps be all you need for prevention. The potassium citrate is raising your urine pH and risk for CaP stones, and even with it your citrate is not all that high – 525. Not sure if it is good or not for prevention – something your physician has to figure out. Regards, Fred Coe
My urine sodium was 125 and My report said Treat with diet sodium 2300-3500 mg/day
Hi Brenda, The tolerable upper limit for diet sodium – urine sodium is diet sodium on average – is 100 mEq which is 2300 mg/d. Thence the note. Fred
So if I’m understanding you correctly I should be consuming no more than 2300 mg/ sodium daily?
Hi Brenda, 2300 mg of sodium is the ‘tolerable upper limit’ of sodium for the US population, so yes. Fred
Hi Dr. Coe. I’ve had 9 stones in my life (from 18 to 55 years old). 4 have been tested, and all were Calcium Oxalate Dihydrate (Weddellite) 15%, Calcium Oxalate Monohydrate (Whewellite) 70%, Carbonate Apatite (Dahllite) 15%.
3 years ago I increased my water intake to 4 liters / day, mixed with 1/2 cup of lemon juice concentrate, but continued a diet medium-high in sodium, low calcium, and high oxalate. In May, I ended up with 2 more 9mm stones (one of which was analyzed as listed above). I then found your site (thank you!) and significantly reduced my sodium intake to ~800-1,000mg / day, calcium ~= 1,000, and ceased eating the super high oxalate (I used to eat a LOT of spinach). I’ve been on this new diet for 3 months now.
My first ever 24/hour urine test just came back from Litholink, and I seem to be a bit unlucky. My urine sodium is wonderfully low, my oxalate is almost ok, but my urine calcium is still relatively high, especially considering how low my sodium is. Considering I don’t get a TON of stones, are my current results good enough, or do I need to do more? For instance, my oxalate intake is ~175mg / day.
Urine Volume: 3.65
SS CaOx: 3.73
Urine Calcium: 290
Urine Oxalate: 31
Urine Citrate: 579
SS CaP: 1.74
24 hour Urine pH: 6.962
SS Uric Acid: 0.04
Urine Uric Acid: 0.456
Na 24: <36
K 24: 103
Mg 24: 129
P 24: 0.847
Nh4 24: 23
Ci 24: <55
Sul 24: 39
UUN 24: 9.01
PCR: 1.1
Normalized Values:
Cr 24: 1420
Cr 24/Kg: 22.8
Ca 24/Kg: 4.7
Ca 24/Cr 24: 204
I also had a CBC and Metabolic blood work done, though 1 day later.
Blood sodium: 139
Potassium: 3.9
Creatinine: 0.95
Bun/Creatinine: 14.7
These values are consistent with the past 5+ years of annual blood work.
Thoughts? TIA!!!!
I should have included my Serum Calcium: 9.0.
Hi Cameron, I believe I already discussed these values for you with a first name Brett – I recognized the urine sodium and calcium. Fred
Hi Dr. Coe,
Thank you for your website, it has changed my life! I am 5’7”, 135lb, semi-athletic, 55-year old male, who has had nine confirmed kidney stones in my life, the first at the age of 19. Four stones have required surgeries, one via SWL and three (including two in May) via lithotripsy. My stone in 2018 and one of the two in May were analyzed as Calcium Oxalate Dihydrate (Weddellite) 15%, Calcium Oxalate Monohydrate (Whewellite) 70%, Carbonate Apatite (Dahllite) 15%, and two previous stones 10+ years ago were also Calcium Oxalate.
In 2018, I increased my water intake to 4-liters/day mixed with 1/2 cup of lemon juice, but was probably ingesting ~3,000mg sodium, < 500mg of calcium/day, and eating a lot of spinach, etc. Not surprisingly, I still ended up with two large stones 3 years later. In May, I discovered your site and have been following a 700-1,000mg sodium, 950-1,100mg calcium and 125-200mg oxalate per day diet since May. As a result of this new diet my chronic hypertension is almost completely gone (reducing Enalapril from 40mg to 2.5mg / day).
I completed my first ever 24-hour analysis last week, with blood work done the next day. My results are below. In consultation with my GP and urologist, I am switching my HBP medication from Enalapril to two 12.5mg Hydrochlorothiazide/day, in the hopes that the HCL will both control my hypertension and lower my urine calcium. I will do a 2nd 24-hour collection in January.
My questions for you are: Should I be concerned re: my urine pH and SS CaP? Do I need to reduce my oxalate intake? Do you believe I have reduced my sodium too much, since my urine sodium is so low? Am I semi-unique in that my urine sodium is <36 but my urine calcium is still 290? I definitely am an outlier on your urine calcium vs urine sodium chart! 🙁
Thank you again for providing such valuable data and insight to all of us!
Urine Volume: 3.65
SS CaOx: 3.73
Urine Calcium: 290
Urine Oxalate: 31
Urine Citrate: 579
SS CaP: 1.74
24 hour Urine pH: 6.962
SS Uric Acid: 0.04
Urine Uric Acid: 0.456
Na 24: <36
K 24: 103
Mg 24: 129
P 24: 0.847
Nh4 24: 23
Ci 24: <55
Sul 24: 39
UUN 24: 9.01
PCR: 1.1
Normalized Values:
Cr 24: 1420
Cr 24/Kg: 22.8
Ca 24/Kg: 4.7
Ca 24/Cr 24: 204
Metabolic blood test results:
Sodium: 139
Potassium: 3.9
Calcium: 9.0
Creatinine: 0.95
Bun/Creatinine: 14.7
Hi Brett, What a great outcome! Lowering diet sodium really does lower BP and the switch to a thiazide is smart in that it will lower urine calcium and replace the pril. With such a low diet sodium and high a water intake, adding thiazide might lower serum sodium, so your physician better check at one week and one month to be sure. I might start with a lower dose of the thiazide, perhaps 12.5 daily – and follow home BP – more predictive than office measurements. I do not think you have lowered diet sodium too much – over 3 liters of urine, lower limit of sodium is partly low intake and partly dilution so we do not really know your total daily sodium loss. But if it were 40 mEq/day, in 3.65 liters of urine, its concentration would be too low to measure Regards, Fred Coe
Ty Dr. Coe! Yes, sorry for the duplicate entry, I wasn’t sure if my original went through. To keep my BP under control, it’s looking like I will be on 25mg of Hydrochlorothiazide, twice a day (my BP was too high on 12.5mg x2). As for follow-up blood work, that is definitely happening. I am excited that I’ll be down to one medication that will hopefully take care of both my hypertension and hypercalciuria.
Is there anything else I should be doing, for instance, should I be concerned re: my urine pH and SS CaP, or since I don’t have a history of Calcium-Phosphate stones, I should be ok in that regard? Thank you again!
Hi Brett, You want SS CaP below 1, but the pill may achieve that. Chlorthalidone 12.5 mg/d does lower urine pH – we published that – so if the OHCTZ does not achieve a low SS CaP perhaps the CTD will. Low diet sodium is important so use 24 hour urine testing to know what it is. Fred
Hi Dr. Coe. I’m having some difficulties with some HCTZ side-effects, the worse being that my tinnitus seems to be worse. I’ve moved up my next 24-urine test to be middle of September (ie, 6 weeks after starting the HCTZ), to see if the HCTZ lowered my urine calcium, so I’ll stay on the HCTZ till after the results are in. My question for you is, with my urine calcium at 290, sodium < 36, and oxalate at 31, how likely is it for me to get more CO stones, if I end up not taking a thiazide (all thiazides seem to exacerbate tinnitus)? Maybe my tinnitus will subside with time, but hasn't so far. 🙁 Sorry for all the questions.
Hi Brett, The best risk assay is the SS for CaOx and CaP; if you can get the former under 3 and the latter under 1 you are pretty safe. Without thiazide, your best BP drug is a sartan – I like Losartan. Be sure and follow home BP as these are most predictive of outcomes. Fred
Funny you mention a sartan! My GP and I have found the correct BP balance for me with the Losartan 50mg / 12.5 HCTZ pill. Hopefully it will help my urine calcium level.
Currently & for the past 3 years, I drink 1/2 cup of lemon juice concentrate mixed with a ~gallon of water / day. I assume the lemon juice is improving my citrate, but is it also contributing to my urine Ph? Should I cut back on it a bit, or leave it well enough alone? Thanks as always!
Hi Brett, As I do not really know the details of your medical situation, I should refrain from too much intervention that might be a disservice. For example the exact balance between citrate and pH response to a citrate load require one see the whole picture – that is your physician. Fred
I understand. My last last question, if you are willing… How is it possible that my urinary sodium is so low (<36) while my urine calcium is still so high (290)? I am concerned that my Intermittent Fasting, in which I ingest ~500mg of calcium twice/day, but only separated by ~4.5 hours is causing (at least in part) my high urinary calcium. Do you believe that is possible? Would it be better to be ingesting ~350mg of calcium via three meals, each separated by ~4 hours?
I've read NIH articles, etc, and I can't find any clear statement, other than non-cited declarations that ingesting too much calcium at one meal causes elevated urinary calcium levels, which I am not sure is true or not! 🙁
Hi Brett, I have presumed you take your calcium as food. Supplements without food is not a good idea. If you must use supplements take them with your larger meals to assure a slower absorption. The problem I alluded to in a prior note is haunting us here. I do not know the details of your stone disease or your life in general, so as I am pushed to provide more detailed advice errors can easily occur. If you want me to provide detailed advice, I do telemedicine and can provide exactly what one would want, at the expense of considerable time and effort for us both. In a public forum, where I am rather ignorant of details, I fear misleading you. Regards, Fred
Hi Brett, There is no basis for estimating. Thiazide lowered stones by about 50% vs. nothing in trials but there are no trials of thiazide vs. low sodium diet. Fred
My kidney stone analysis does not seem to say much to me as a patient.
And what does DNR mean in a kidney stone analysis. “Do not resuscitate” does not make sense here, but the internet does not seem to give me clues.
History:
2011: 1st kidney stone, Lithotripsy.
It was treated as a one-off, no follow-ups, not dietary instructions, no warning that more could develop in the future
2021: tiny sensation in lower back for a couple of days, not even real discomfort, just a slight awareness. Felt like a hyperchrondriac to even go the Dr. , 2-week wait to see my doctor, so I saw a PA who ordered an “urgent” CT, took a week to get a doc to sign off on that, had emergency surgery the next day, a huge kidney stone in each kidney. Left kidney no functioning at 6% not addressed because too risky. Right kidney 94%, apparently blockage so temporary stent. 3 weeks later Lithotripsy, but large amount of detritus from lithotripsy. I had asked for a stone analysis so that I could adjust my diet as necessary. The mysterious results follow:
____________________________________________________________________
Details
Past results [Note: No test after my 2011 kidney stone]
Graph of past results
Component results
Component Your value Standard range Flag
Specimen Source RIGHT KIDNEY STONE
Component 1 See Below [Note: Nothing was below]
Component 2 DNR [What does DNR mean in this context?
Stone weight 0.007 gm
gm
General information
Ordered by: XXX XXX, MD
Collected: 08/06/2021 9:40 AM from OTHER
Resulted: 08/13/2021 12:37 AM
Result status: Final result
This test result has been released by an automatic process.
Hi Lois, I think the lab could not determine the composition in that the sample was only 7 mg (0.007 gm) – although it should have been enough. Another possibility is that the part below had a note not sent to you with the information. Your physician would have that. Given you have lost function in one kidney and there was a large stone in the other, I am concerned for you. Take a look at a plan about how to proceed as a kidney stone former. Given only one kidney prevention and urological management is very critical and perhaps your physicians might want to make a referral to a major stone center convenient to you. If you tell me where you live, I can try to help with a suggestion. Regards, Fred Coe
DNR here is Do Not Report
Thank you for helping me interpret the results of my recent 24 Hour Urinalysis by Quest Diagnostics Nichols Institute, below. This specimen was collected one month after I passed the 6mm stone mentioned in my March 3, 2023 response to your “Fluids, Diet, and Meds for Common Stones” page, which the lab identified as Calcium Oxalate Dihydrate (Weddellite) 20% and Calcium Oxalate Monohydrate (Whewellite) 80% (I have a good photo of the stone but was unable to post it).
SPECIMEN VOLUME: Your value 3.34, Standard range >2.00
PH: Your value 6.3, Standard range 5.5 – 7.0
CALCIUM: Your value 189, Standard range <250.0
OXALATE: Your value 31, Standard range <45
URIC ACID: Your value 655, Standard range 320
SODIUM: Your value 97, Standard range <200
SULFATE: Your value 16, Standard range <30
PHOSPHATE: Your value 912, Standard range 60.0
AMMONIA: Your value 43, Standard range 14 – 62
POTASSIUM: Your value 60, Standard range 19 – 135
CREATININE: Your value 1284, Standard range 800 – 2000
CALCIUM OXALATE INDEX: Your value 0.79, Standard range <2.00
BRUSHITE SATURATION FRACTION: Your value 0.93, Standard range <2.00
SODIUM URATE SATURATION FRACTION: Your value 0.49, Standard range <2.00
STRUVITE SATURATION FRACTION: Your value 0.76, Standard range <75.00
URIC ACID: Your value 0.47, Standard range <2.00
24HR URINE STONE RISK COMMENT: No metabolic abnormalities detected.
Below are my notes for reference; this diet and intake are typical following stone diagnosis (previously high oxalates, low calcium, insufficient hydration). Perhaps I can get away with being less strict about oxalate intake?
collection start: 2023-04-08 07:30 (before breakfast)
collection end: 2023-04-09 07:30 (before breakfast)
collected volume: about 1.5" from top of non-graduated container
consumed volume: 3750 ml
~3000ml water with lemon juice throughout day (citrate to bind with calcium in kidneys)
dinner (prior to collection):
half of one homemade pizza
crust: flour (OO, spelt, white whole wheat, wheat, pastry), olive oil, yeast, malt powder, pinch of salt
toppings: tomato sauce, Asiago cheese, onion, bell pepper, capers, oregano, crushed red pepper, fresh arugula
swig of 2% kefir (calcium to bind with oxalates in gut)
evening (prior to collection):
air-popped white corn lightly buttered with pepper
breakfast:
~250ml tea
~250ml coffee with cream
one slice of whole grain sourdough toast with 1/4 of fresh avocado, lightly salted
swig of 2% kefir (calcium to bind with oxalates in gut)
lunch:
second half of pizza described above
swig of full fat kefir (calcium to bind with oxalates in gut)
afternoon:
unsalted tortilla chips and salsa
swig of full fat kefir (calcium to bind with oxalates in gut)
dinner:
roasted cauliflower and broccoli, olive oil, black pepper, lightly salted
swig of full fat kefir (calcium to bind with oxalates in gut)
evening:
air-popped white corn lightly buttered with pepper
night:
~250ml plain water (without lemon juice)
Hi Jim M, Your urine results are all normal, so given this one sample there are no clues as to why you formed stones. A common reason given this is that urine volumes have been substantially lower or diet substantially different in years past and caused stones. Regards, Fred Coe
Hey, Dr Coe.
In reading through the comments above the first gentleman had very similar Urine Volume and Calcium in the 24 hr urine results, but my Brushite saturation is at 2.3 (Quest diagnotstics as well) The only thing I can see is that my PH 7.0 is driving the Brushite saturation. Been working to bring up Citrate (still a little low) but have brought my PH up from 6.2 to 7.0….. Any way to improve Citrate without a corresponding rise in PH?
If I had to choose between reducing my citrate to reduce PH to get my Brushite back in line, Is that a trade worth making?As a note, When my PH was 6.2 with similar volume, by Brushite SS was below 1, which I believe is where I need to be. Calcium OX ss is currently below 1.
Hi Michelle, When citrate is low and stubborn about rising despite a very high urine pH the most plausible cause is one of the renal tubular acidosis genes. Not the full blown disease, often, but having one abnormal version and one normal – heterozygous. The other is drugs that might compromise renal acid excretion. Check all of your meds online and see if any do this. Finally, calcium phosphate stone formers can have this behavior but I think many are heterozygous for renal tubular acidosis. Let me know the answer. Regards, Fred Coe
Thank you for the prompt response. The only medication I take is Hydrocholorothiazide. Any suggestions for a go forward strategy?
Hi Michelle, possibly the OHCTZ is lowering your citrate because of mild potassium depletion – serum values need not be below normal. The drug is very weak for stone prevention. I would drop it in favor of chlorthalidone – perhaps 12.5 mg/d with potassium chloride 20 mEq/d or more. This will protect you better and the KCl may increase your citrate. Ask your physician if he/she thinks this is not unreasonable. Regards, Fred Coe
11 mm kedney stone
Hi Mohd, That is a reasonable size stone and you should have a urologist evaluate your situation. Regards, Fred Coe
I just got my results from the 24hr. urine. I have a history of stones dating back 20 years. Last year, I had stones in both kidneys and bladder. I’ve since moved and knowing my history my Dr. order CT when my Ua showed blood.
Again, stones in both kidneys & bladder. I had suspected BPH which the former urologist said was not a problem. My Dr. now said it was enlarged and we did a TURP with the first Lithotripsy. Not wanting to keep me under too long, we did 2 phases. Litho & TURP, then was to wait a month for next Litho for rest of stones. Unfortunately stones blocked the stent and I would up in ER. So, my second lithotripsy was done a couple of days later.
Since al this, I have increased my fluid intake and eliminated most tea from my diet. I am also a heart failure patient, so had been limiting my fluids. I now realize I limited too much.
My concern is that by increasing the fluids just prior to the 24hr specimen, it may have skewed the results.
From reading your info, I do see that I am prone to stones though.
I would appreciate any thoughts.
CYSTINE, URINE, QUALITATIVE Neg
Negative
URINE VOLUME (PRESERVED) 3,290 mL/24 hr
500 – 4,000 mL/24 hr
CALCIUM OXALATE SATURATION 4.65
6.00 – 10.00 L
CALCIUM, URINE 241 mg/24 hr
450 mg/24 hr L
CALCIUM PHOSPHATE SATURATION 1.60
0.50 – 2.00
PH, 24 HR, URINE 6.769
5.800 – 6.200 H
URIC ACID SATURATION 0.08
<1.00
URIC ACID, URINE 615 mg/24 hr
<800 mg/24 hr
SODIUM, URINE 183 mmol/24 hr
50 – 150 mmol/24 hr H
POTASSIUM, URINE 43 mmol/24 hr
20 – 100 mmol/24 hr
MAGNESIUM, URINE 97 mg/24 hr
30 – 120 mg/24 hr
PHOSPHORUS, URINE 1,060 mg/24 hr
600 – 1,200 mg/24 hr
AMMONIUM, URINE 30 mmol/24 hr
15 – 60 mmol/24 hr
CHLORIDE, URINE 156 mmol/24 hr
70 – 250 mmol/24 hr
SULFATE, URINE 18 meq/24 hr
20 – 80 meq/24 hr L
UREA NITROGEN, URINE 8.00 g/24 hr
6.00 – 14.00 g/24 hr
PROTEIN CATABOLIC RATE 0.6 g/kg/24 hr
0.8 – 1.4 g/kg/24 hr L
CREATININE, URINE 1,406 mg/24 hr
Not Applic. mg/24 hr
CREATININE/KG BODY WEIGHT 11.4 mg/24 hr/kg
11.9 – 24.4 mg/24 hr/kg L
CALCIUM/KG BODY WEIGHT 2.0 mg/24 hr/kg
<4.0 mg/24 hr/kg
CALCIUM/CREATININE RATIO 172 mg/g creat
34 – 196 mg/g creat
Hi Durward, You do not mention what the stones are made of. I presume calcium oxalate. You do not list the 24 hour urine oxalate but I suspect it is high given the SS for CaOx is 4.6 with a urine calcium of only 271 and a volume of 3 liters. More information might make me a better help. Regards, Fred Coe
I just got my results back from my 24 hour urine. They done a stone analysis for my last stone attack in July. As a 55 year old woman, I had never had kidney stones until a year ago and my body started forming them. Since that time, I have had 7 stones, 7 surgical procedures and it has been miserable.
Cystine, Urine, Qualitative Neg
Urine Volume (Preserved) 1,880 mL/24 hr
Calcium Oxalate Saturation 4.02
Calcium, Urine 1 171 mg/24 hr
Oxalate, Urine 1 25 mg/24 hr
Citric Acid (Citrate) 1 180 mg/24 hr
Calcium Phosphate Saturation 1.55
pH, 24 Hour Urine 6.569
Uric Acid Saturation 0.24
Uric Acid, Ur 710 mg/24 hr
Sodium, Ur 142 mmol/24 hr
Potassium, Ur 44 mmol/24 hr
Magnesium, Urine 89 mg/24 hr
Phosphorus, Ur 822 mg/24 hr
Ammonium, Urine 44 mmol/24 hr
Chloride, Ur 138 mmol/24 hr
Sulfate, Ur 42 meq/24 hr
Urea Nitrogen, Urine 11.73 g/24 hr
Protein Catabolic Rate, Ur 0.9 g/kg/24 hr
Creatinine, Ur 1,002 mg/24 hr
Creatinine/Kg Body Weight 10.1 mg/24 hr/kg
Calcium/Kg Body Weight 1.7 mg/24 hr/kg
Calcium/Creatinine Ratio 171 mg/g creat
I drink about 80 or more oz of water a day. I walk 1-2 miles a day. I rarely add any salt to my food. I rarely eat processed or fast food. Trying to determine best course of action on what is causing the stones and what to prevent then. Thank you, Liz
Hi Liz, Your data show no obvious stone forming issues apart from a high pH. You do not mention the stone analysis but it could be calcium phosphate. I suspect you are forming stones for reasons not obvious in these labs. As an example, primary hyperparathyroidism can cause stones in mid-life. Is your fasting serum calcium normal? Perhaps something else, like bone disease with increased bone mineral loss into urine? From here I am afraid I cannot say more. Regards, Fred Coe
My chemical analysis of my stone is below:
Calcium Oxalate Dihydrate (Weddellite) 20%
Carbonate Apatite (Dahllite) 80%
Stone Weight .0005
I don’t believe they have completed a fasting serum calcium test. Thank you for your feedback.
Liz Lewis
Hi Liz, Let me know – out of interest. Fred