HOW TO READ YOUR KIDNEY STONE LAB REPORT – Calcium stones

IMG_2303Jeff, 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 hypercalciuriaThe 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.

 

49 Responses to “HOW TO READ YOUR KIDNEY STONE LAB REPORT – Calcium stones”

  1. Christa

    Hi Dr. Coe, I am in the middle of taking Jill’s course and it has been helpful. I had lithotripsy in 2009 that resulted in me ending up in ICU followed by the need for a cardiac ablation. CT in 2012 showed 15+ stones, current sonogram show about 3 (6mm). My question for you: I had (1) 24 hr urine in 2012 and (3) 24 hr urines this year. They are all over the place and have little consistency. It is VERY frustrating knowing how to proceed and sadly I have not had good experience with finding the right guidance. In the beginning of the year I was put on blood pressure medicine and feel that has been the cause of the varying results this year. Is that possible? For 1 month I was on a diuretic (indapamide) and the numbers on the 24 hr urine went bonkers so I was then switched to Norvasc and they changed again. Any feedback would be greatly appreciated!! My greatest thank you!!!
    VOL SSCaOX Ca24 Ox24 Cit 24 SS CaP pH SSUA UA24
    10/31/17 3.63 2.26 206 25 429 .24 5.827 .62 .790
    9/26/17 4.15 1.01 74 26 273 .13 6.266 .17 .567
    5/02/17 2.63 2.83 91 37 711 .20 6.044 .46 .630
    7/23/17 1.79 6.67 167 38 600 .82 6.106 .56 .615

    Reply
    • Fredric Coe, MD

      Hi Christa, It would appear that you raised your urine volumes, perhaps raised your diet calcium, as time went on. I do not see much chaos. YOur present stone risk looks rather modest. But in all fairness, this is not a medical opinion, merely a brief note about the measurements. In the latent 24 hour urine calcium is just at the risk threshold, oxalate creates no risk, but urine citrate is a bit low. Perhaps the diuretic caused some potassium loss. I see 4 studies in 2017 and none in 2012, by the way. Are you sure you are still forming more stones? YOur chemistries are not very worrisome. Regards, Fred Coe

      Reply
  2. Pam Dickie

    Hi Dr. Cole,
    I received my 24 hour urine results and need help interpreting results please. There is a lot to consider. Thank you!

    Day 1 Day 2
    Vol 1.56 1.56
    SS CaOx 9.90 10.13
    Ca 240 242
    Ox 44 45
    Cit 943 785
    SS CaP 2.96 3.56
    pH 6.891 6.852
    SS UA 0.13 0.15
    UA 0.689 0.715

    Dietary:
    Na 177 143
    K 83 88
    Mg 112 109
    P 0.743 0.923
    Nh4 19 25
    CI 174 140
    Sul 35 38
    UUN 8.15 8.51
    PCR 1.1 1.1

    Normalized Values:
    Cr 1420 1530
    Cr 24/kg 25.7 27.6
    Ca 24/kg 4.3 4.4
    Ca 24/Cr 24 169 158

    Reply
    • Fredric Coe, MD

      Hi Pam, Here is what I can do: Tell you technically what the numbers tell me. But for your care you need your physician to be in charge and take responsibility. Your urine volume is low, calcium is high, oxalate is high – usually the latter is low calcium diet. Your urine is alkaline and supersaturated with calcium phosphate and oxalate so you have considerable stone risk. Your sodium intake is high and that will raise your urine calcium. I wonder if you take potassium alkali as your urine MH4 is low, but perhaps you eat a lot of fruits and veggies. You are low in body fat, something rather prized these days. Speak to your physician about higher diet calcium for the oxalate and much less diet sodium – 1500 mg is ideal – for the urine calcium. Your citrate and pH are so high that potassium citrate are not advisable. But do not do these things without his/her review and analysis. Regards, Fred Coe

      Reply
  3. Liz Dodd

    I am 40 years old and have had kidney stones since I was 16. They have increased in size dramatically lately & are occurring more frequently. I recently had a 24 urinalysis & am wondering if you could help me understand the results more clearly. I am just going to give you what I have, sorry if it is way too much info.
    CA Oxalate Crystal 0.89 DG
    Brushite Crystal -1.09
    Hydroxyapatite Crystal 5.19 DG
    Uric Acid Crystal -4.73
    Sodium Urate -1.52
    Length of Collection, 24 Hr UR 24 h
    Volume, 24 HR UR 4000mL
    Interpretation
    The DG is related to supersaturation. DG is negative for undersaturated solutions, zero for solutions at the solubility product, and positive for saturated solutions. Any value greater than the Reference Mean is considered a risk for the respective crystal type formation.

    Sodium 56 mmol/24 h
    Potassium 24 mmol/24 h
    Calcium 280 mg/24 h
    Magnesium 160 mg/24 h
    Chloride 44 mmol/24 h
    Phosphorus 160 mg/24 h
    Sulfate 12 mmol/24 h
    Citric Acid 84 mg/24 h
    Oxalate 0.20 mmol/24 h
    Oxalate 17.6 mg/24 h
    Ph, Urine 6.7
    Uric Acid 640 mg/24 h
    Creatinine 920 mg/24h
    Osmolality 112mOsm/kg
    Ammomnia 20mmol/24 h
    Urea nitrogen 6.7 g/24 h
    Protein Catabolic Rate 67 g/24 h

    I also had a PTH Intact Test, those results were 16.0 pg/mL

    Like I said, I hope I am not giving you way too much information or presenting it in the incorrect way. I was told that I have a severe citrate deficiency. If you would please let me know what your thoughts are I would really appreciate it!
    Thanks so much!

    Reply
    • Fredric Coe, MD

      Hi Liz, Your urine volume is high, sodium low, calcium hefty – I am sure you have genetic hypercalciuria, and pH is high. Do you form calcium oxalate or calcium phosphate stones? Of interest your urine potassium is very low and your urine ammonia exceeds sulfate as occurs with potassium depletion. Your citrate is indeed low, but potassium depletion does that. Have you had vomiting, diarrhea, or diuretics that lowered your potassium stores? Is your serum potassium perhaps low, or serum bicarbonate? Given the present picture of slight supersaturations, low citrate, and lots of stones, perhaps a diuretic – to lower urine calcium further – would be ideal along with potassium citrate. Even potassium chloride might help and not increase urine pH further. Ask your physician what he/she thinks. I like chlorthalidone, 12.5 mg daily. Regards, Fred Coe

      Reply
  4. Stacy

    Dr Coe,

    I’m having trouble relating my results.

    Stone Risk Analysis
    Ca Oxalate 2.65 (<2.00)
    Brushite 6.4 (<2.00)
    Sod Urate 5.83 (<2.00)

    Urinalysis
    PH 7.0
    Protein 100ml/dl
    Blood trace-lysed

    Stage 2 CKD, labile hypertension and sinus tachycardia. Could these be caused by the stones or vise versa? Also very high renin and aldosterone.

    Reply
    • Fredric Coe, MD

      Hi Stacy, I guess there are not a lot of numbers here for me to look at. Stone formers have an increased risk of kidney disease and hypertension, so your high blood pressure is not a surprise. The very high CaP supersaturation – Brushite 6.4 – suggests a high urine pH and perhaps high urine calcium, but there are no values. If you would share more, I could try to help more. Regards, Fred Coe

      Reply
      • Stacy

        Thanks for responding, Dr!
        All of the other results were normal.
        Sodium- 152
        Sulfite- 11
        Phosphorus- 649
        Magnesium- 69
        Ca Oxilate- 2.65
        Brushite- 6.40
        Sos Urate- 5.83
        Struvite- 13.38
        Utica A Sat- 0.21
        Ammonium- 16
        Potassium-28
        Creatinine- 1279
        PH- 7.0

        Renin- 25.8 (range 0.5- 4)
        Aldosterone- 48.2 (range 5-30)

        Ultrasound of Kidneys:
        Right- 9.7 * 3.6 * 5.5cm, several small central callus cases may be vascular small kidney stones.

        Left- 9.4 * 5.2 * 4.9cm, mildly dilated central renal collection system.

        Abdominal CT w/o Contrast:
        Small scattered bilateral nephrolithiasis is identified up
        to 2 mm in size. These are more numerous on the left. Mildly
        pronounced extra renal pelvis of the left is noted without
        caliectasis. Both ureters are difficult to follow however no
        definite ureter calcifications are identified. Right pelvic
        calcification image #80 is present felt to be medial to the
        expected region of the right ureter. Mild/moderate
        prominence is suggested of the uterus. Small dependent fluid
        in the pelvis.

        First large stone passed at age 14, about one or two per year since, although not nearly as painful as the first few. Had severe left flank pain for 3 years from ages 20-23 but doctors dismissed as drug seeking. Still have mild to moderate intermittent bilateral flank pain.

        Six years ago at age 26 while pregnant, developed severe labile hypertension and sinus tachycardia. It has worsened over the years.

        Wondering (getting desperate) if possible nutcracker syndrome of an accessory left inferior pole renal artery would show on arteriogram? My symptoms are orthostatic typically. But I suppose that would not explain the kidney stones on the right side..

        I appreciate your help so much, Dr! Thank you!

        Reply
        • Fredric Coe, MD

          Hi Stacy, This is very complicated but your brushite SS is high! and your urine very alkaline – pH 7. I put my main questions there. Why so alkaline a urine? Urine sodium is very high, potassium very low, you have almost no urine sulfate – low protein intake – your urine ammonia exceeds your sulfate, all of which points to possible potassium depletion. The high renin and also suggest that despite the high urine sodium you are stimulating these hormones that usually rise with body volume depletion. Do you take diuretics? Have you been vomiting? Your physicians need to make sense out of these measurements. I cannot do much more from here. But perhaps if you mention these comments to them they will know why. Regards, Fred Coe

          Reply
          • Stacy

            Thank you Dr!

            The urologist that ran the test recommended I drink lemon water and wasn’t concerned since the stones weren’t large. I’ll take this info to my next nephrology appt and hope he has an idea. Would you recommend potassium supplement and an increase of salt? Maybe Gatorade? My only medications are Losartan for BP, Corlanor for sinus tachycardia, and occasionally Clonidine for hypertensive crisis, but I try to avoid as it seems to cause a rebound spike and makes me feel pretty gross. When I was prescribed a diuretic a few years ago for BP, it made my palpitations very severe and I fainted at work. If you are accepting new patients, I could travel to see you and pay cash. Or if you might be able to recommend certain tests I can request? I feel like all of my symptoms are related and I’m just not able to put my finger on a cause or treatment. Thank you so much!!

            Reply
            • Fredric Coe, MD

              Hi Stacy, Lemon water is a bit silly, isn’t it? You already have an alkaline urine and high brushite supersaturation. As for sodium you already have a lot in your diet and therefore in your urine. It sounds like you have rather severe hypertension as well, given use of Clonidine. Your nephrologist sounds like a more promising person to figure out what to do. If you are indeed potassium deficient it would be potassium chloride to take – not the citrate. But the alkaline urine pH is an issue for him/her to figure out. I could always see you if your physicians felt it was important, but usually personal physicians can take care of things. Regards, Fred Coe

              Reply
              • Stacy

                Thank, Dr.
                I wonder about the high urine sodium.. As I do not eat a high salt diet, although not technically low sodium either. The DASH diet made my symptoms worse for no good reason! Also, my blood sodium levels tend to run a little low, either the bottom side of normal or even slightly under normal.

              • Fredric Coe, MD

                Hi Stacy, Sodium in your urine is sodium you ate. A good goal is 1500 mg/d. Blood sodium will not fall in a normal person eating such a diet unless she is taking a diuretic drug, or has been vomiting or has diarrhea. Regards, Fred Coe

  5. Lisa Funari

    Hi Dr. Coe,

    I just received my Litholink results back and everything was in normal range with the exception of Citrate at 191 and pH at 7.092. I have been on 50-100mg of Topomax for close to 10 years for migraines, and after doing my research saw that this can lead to the low citrate levels. My uro just put me on 30 mEq of potassium citrate and I’m going to stop the Topomax. My concern now is getting the pH level fixed. Do you believe stopping the Topomax and getting the citrate level back up to normal will help the pH level, or should we be looking for a different reason that could be causing the higher pH level? Thank you for your help!

    Reply
    • Fredric Coe, MD

      Hi Lisa, this drug causes high urine pH and low citrate by its very chemical nature. If you have no stones, I am not sure why testing was done. But if you are concerned stones may form it is best to change to another drug. The urine citrate will not rise much with k citrate so long as you take the drug, but should rise when you stop it. Regards, Fred Coe

      Reply
      • Lisa Funari

        Hi Dr. Coe, Thank you for your response. I have had stones for about 10 years now and generally pass 1 or 2 per year. I stopped the Topomax the day I wrote the post to you and have been off of it for 2 weeks now. My uro had me stop the K pills as well to see if the Topomax was the issue and I am repeating my Litholink test in a couple of days (2 weeks post stopping medicine). So my question is two fold:
        1. Should stopping my Topomax without taking the K pills be enough to raise he citrate level alone or would I be better off taking the K pills after stopping the medication in order to help raise the level?
        2. Would taking the K pills help dissolve the stones that I do have so I wouldn’t have to worry about them? My stones are always Ca stones?
        Thanks!

        Reply
        • Fredric Coe, MD

          Hi Lisa, The Topamax causes renal tubular acidosis. That disease effect raises urine pH so calcium phosphate stones form. Potassium is always lost in the urine for complex reasons – yes, an article on RTA is long overdue. So you will be potassium depleted. Most potassium is in the cells, so even when your serum level is normal kidney cells may continue to take up citrate leaving little for the urine. The potassium you need is potassium chloride; the citrate is counterproductive right now. No, the stones – usually calcium phosphate – will not dissolve, unfortunately. As well you may have other causes of stones, so the followup study is very important. Regards, Fred Coe

          Reply
        • Fredric Coe, MD

          Hi Lisa, The Topamax causes renal tubular acidosis. That disease effect raises urine pH so calcium phosphate stones form. Potassium is always lost in the urine for complex reasons – yes, an article on RTA is long overdue. So you will be potassium depleted. Most potassium is in the cells, so even when your serum level is normal kidney cells may continue to take up citrate leaving little for the urine. The potassium you need is potassium chloride; the citrate is counterproductive right now. No, the stones – usually calcium phosphate – will not dissolve, unfortunately. As well you may have other causes of stones, so the followup study is very important. Regards, Fred Coe

          Reply
  6. Kate Mulcahy

    Dr. Coe – I received my results from the 24-hour urine sample and by urine pH is 6.634. Everything else seems to be in the normal range. I am not sure how to adjust my diet to lower my risk of stones. Could you help?
    My other results:
    Urine volume – 2.49
    SS CaOx – 3.37
    Urine Calcium – 125
    Urine Oxalate – 29
    Urine Citrate – 712
    SS CaP – .76
    24 hour urine pH – 6.634
    SS Uric Acid – .08
    Urine Uric Acid .371

    Thanks, Dr. Coe. I sure appreciate your guidance.

    Kate

    Reply
    • Fredric Coe, MD

      Hi Kate, I wonder if things have changed since you formed stones so that whatever increased your risks is gone. right now there is nothing to do, so far as I can see. But I am looking at mere numbers and your physician knows your whole story and surely can see more into the problem. Regards, Fred Coe

      Reply
      • Kate Mulcahy

        Thanks, Dr. Coe. I always appreciate and value your good guidance for all of us.

        Reply

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