24-Hour Urine Collections: Why and How

Jill jpegWhy

You have a kidney stone episode and your doctor asks you to collect your urine for 24 hours. Why oh why is this being asked of you? Isn’t it dreadful enough that you just had a kidney stone?

The only way to find out WHY you are forming kidney stones is to complete a urine collection.

The test results will tell your doctor how saturated your urine is with stone making crystals.

The more saturated your urine is, the more likely you are to form new stones.

Some clients have come to me and said, “Why do I need to do a urine collection if the doctor removed my stone and had it analyzed?”

A stone analysis may tell you what type of stone you made, but there are many different reasons you may have made that type of stone.

Figuring out your prevention plan is very complicated, and without a urine collection it is nearly impossible.

Figuring out all of the details behind urine collections can be exhausting. I just released a course called The Kidney Stone Prevention Course to help you understand how to implement your physician’s prescribed treatment plans.


One Day or Two Day Collections?

When you do your first collections, the ones your treatment is going to be based on, it is wise to do two: Two 24 hour urine collections.

Before you start pulling your hair out, let me tell you why.

What you eat and drink during your collection is going to be represented by your test results. If you do your collection on your birthday, you may be celebrating, drinking, eating foods you don’t usually eat and this will not represent a “normal” day for you.

If you do two collections, your test results will show a better picture of what you are eating and drinking.

Sometimes I see a two day collection and the day to day results are so very different they enable me to ask some important questions. For example, “The sodium levels in your urine were very high on your first collection, did you go out to eat that day?”

When I worked at Litholink Corporation we would tell patients to collect their urine on a weekday and a weekend day.

We requested the collection be completed this way because typically what we eat during the week is not what we eat during the weekend.

This way the lab results would show the difference between eating and drinking habits and we could offer better treatment suggestions to the doctors on the lab report.


Always Drink and Eat Normally

Many patients don’t want to hear their doctor scold them for not drinking enough so when they do their urine collection they drink and drink and drink. This is not what they usually do. Some already know they were eating badly and made some big changes so their tests would look better.

Why am I going to call you out on this? Am I just a pain in the neck?


Cheating on Your Collection Days Will Not Help

If you drink more than you usually do or eat differently than you usually do, your doctor will base your treatment plan on what you did for those days.

You want your treatment plan to be based on what you usually did when you formed stones so that changes you make will lessen your chances of making more stones.

Suppose you already know you should drink more water, and you do it during your collections. You never did it before, when your stones were forming. Your doctor sees that you’re drinking 4 liters of water a day (you wanted to impress him or her).

S/he will be impressed and assume that low fluids were not and will not be your problem.

But, maybe low fluids were your problem. You won’t know and neither will your doctor.

So what?

No one, including you, will make fluids a priority and you may well forget to keep showing off.

Then what?

Maybe nothing else was wrong except low fluids, and that was gone for the moment – when you did the tests.

Maybe the fluids have already fallen back to your original low levels.

Your doctor will not be able to offer you any help, or worse, may tell you something generic like “avoid all green, leafy vegetables”. I don’t want anyone avoiding green, leafy, veggies if they don’t have to.

I tell clients, “if you drink gin all day then please do that during the test”.

If you don’t drink much water, please do as you normally do.

Getting on the right treatment plan is imperative in preventing new stones from forming. The only way to get on the right treatment plan is to eat and drink as you normally do on the days you are collecting your urine.


Diet Changes Before Collection Begins

Some of you were told to change your diets before doing the urine collection and wind up doing the collection while on your new diet.

This will NOT help.

You want your results to show what you did while you were making stones. For the day(s) you are asked to collect your urine, eat as you did before you knew you had a kidney stone.

Then go back to doing what your doctor told you to do or what s/he tells you to do after the test results are available.

Don’t Collect During Holidays

Many people will want to do their collection on the holiday because they are off work. If you are like me, you eat differently on holidays than you do on non-holidays.

Thanksgiving is not representative of how you normally eat, so this is not the time to do your collection.

Remember, since your results will show what you ate for that particular day, a treatment plan based on holidays will not be useful to you. Your doctor may tell you to go on certain diets that you do NOT have to go on.

That would not be helpful at all!

Make Time to do the Urine Collections

I completely understand that doing a urine collection is a total pain in the neck. It is annoying and nothing you want to do.


There is nothing quite as bad as having a stone attack. If you have to weigh one against the other, doing a urine collection is the clear winner.

Find the time. It’s worth it.

Occupation Need Not be a Barrier

I have had pilots, truck drivers, surgeons, salespeople, and teachers all find the time and make collections while at work. Whether or not it is possible depends on a lot of circumstances, but doing it on the job is the ideal for one of your two days.

Some of you will not be able to bring the collection jug to work.

Perhaps you might have to take a day off from work.

If you do take a day off from work, please drink and eat as you normally would on a work day.

If you do a two-day collection, remember to do one on a weekend so your doctor can see how it differs from a weekday.

Questions About Your Collection

Once you receive your urine collection, please read all instructions on how to complete it.

If you have any questions, call the place of business you received your supplies from and ask them all the questions you may have before starting the collection.

It is dreadful when you have to re-do a collection because you didn’t do it the way they wanted you to.

Follow-up Collections

Once you do your initial 48-hour urine collection, the doctor will go over the results with you.

From those results, you will be told to do certain things that will help prevent stones in the future. You may be told to go on medications, drink more water, change your diet, or all three.

Four to six weeks after you have incorporated all the changes your doctor has prescribed for you, your doctor SHOULD ask you to do a 24-hour urine collection to make sure those changes are working for you.

If you don’t do a follow-up, how will you know if your treatment plan is working?

If your doctor doesn’t order a follow-up, ask for it.

You should expect your doctor will contact you about your results and make whatever changes are needed to get you the best possible prevention.

Annual 24-Hour Collections

Our urine chemistries change over time. It is prudent that you complete a yearly collection to ensure your treatment plan is still working for you.

Partly urine chemistries change because we are getting older, or have developed some new disease condition.

Diets change even if we are unaware of the changes because they occur slowly.

We gain or lose weight which can affect urine chemistries.

Our habits change: We give up or get a health club membership, or start running.

A Final Thought from Jill

Clearly now, you can see how important it is to complete urine collections.

I want you to know that I don’t ask you to see the importance of doing these darn collections without having compassion and empathy that you have to do them.

I know they are not convenient, nor are they fun.

Just keep in mind that if you don’t complete a urine collection, you will not know why you formed stones and will most likely keep right on forming them.  I want to keep you away from that scenario.

Prevention is always our best defense. Completing your collections is a pretty benign way to keep stones at bay.

Return to Walking Tour about Supersaturation

Figuring out all of the details behind urine collections can be exhausting. I just released a course called The Kidney Stone Prevention Course to help you understand how to implement your physician’s prescribed treatment plans.


86 Responses to “24-Hour Urine Collections: Why and How”

  1. Margie

    Hi Dr. Coe and Jill Harris,
    The morning of my 24 hr test I called the nurse to check on whether or not to drink lots of water during the test. She advised I drink “at least” 64 oz. I mentioned the Dr. said not to alter my normal pattern and eat everything as usual, so I thought maybe I should only drink my normal amount which is not nearly that much. I followed her advice and now I feel like my results are not accurate. My urine volume was 3,200 mL, way more than my normal daily output.
    Yes, I did toss the first pee of the day.

    Also, the test results only showed Calcium, Phosphorus and Uric acid. Your article reads like there should be more things checked.
    Thanks, Margie
    CalciumTimed Urine 3.2 mg/dL, Calcium Urine Excretion 102 mg/D
    Phosphorus Timed Urine 14.3 mg/dL, Phosphorus Urine Excretion 0.5 g/D
    Urid Acid Timed Urine 15.1 mg/dL, Uric Acid Excretion 483 mg/D

    • Fredric Coe, MD

      Hi Margie, Usually physicians order a panel of tests that give more information for a bargain price. But the calcium is low as I noted below and the other two tests add nothing special. Regards, Fred Coe

    • Fredric Coe, MD

      Hi Margie, As I wrote in my other reply, your urine calcium is low normal, the other two measurements of marginal value and not abnormal. Commercial vendors offer a comprehensive panel that is more informative. Regards, Fred Coe

  2. Andrea

    I am trying to figure out what it is ment by supersaturation, urine, abnormal.

    • Fredric Coe, MD

      Hi Andrea, You are a sharp reader. Up to now, we have not had good links between SS and stone risk. So we always use a paradigm: In a person actively producing kidney stones, the urine SS with respect to the crystals in the stones is too high; reduce it. For uric acid as a special case, any SS above 1 is a risk and we need to lower it below 1. Recently we have new findings that actually give stone risk for a given level of SS and I mean to publish this as soon as I am able. Regards, Fred Coe

  3. Barb J

    What piece is missing?
    I have been followed since May 2017 for consistent elevated levels of protein, albumin/creatinine, erythrocytes, leukocytes. No CT scan. Only ultrasound showing embedded stone and cysts. My last 24 hour collection specimen volume was 0.70 L/day, 9.6 mmol/L creatinine, 6.7 mmol/day (24 hour urine), protein 0.42 g/L, 0.29 g/day (24 hour urine). I am somewhat perplexed. Nephrologist also seems unconcerned but I am. I see a kidney internist next, hoping to get more answers. What should I be asking for? Diet next steps? Water intake goals? I feel like I am stuck in some kind of freaky kidney time warp paralyzed not knowing what’s causing this and waiting on standby hoping for a clear diagnosis and treatment plan.
    Love from Canada! BJ

    • Fredric Coe, MD

      Hi Barb, Your urine volume is scanty given you form stones. I calculate you have about 380 mg/gm creatinine of urine protein, which is a bit elevated. But if there is blood in the urine, that protein may be because of bleeding not intrinsic renal disease. So perhaps your problem is stones, bleeding, consequent urine protein increase, and the real issue is stone prevention. Of course I do not know your serum creatinine so I cannot judge your kidney function. About your stones I can say little except so remarkably low a urine volume confers considerable stone risk. Regards, Fred Coe

    • Fredric Coe, MD

      Hi Barb, Your urine volume is scanty given you form stones. I calculate you have about 380 mg/gm creatinine of urine protein, which is a bit elevated. But if there is blood in the urine, that protein may be because of bleeding not intrinsic renal disease. So perhaps your problem is stones, bleeding, consequent urine protein increase, and the real issue is stone prevention. Of course I do not know your serum creatinine so I cannot judge your kidney function. About your stones I can say little except so remarkably low a urine volume confers considerable stone risk. Regards, Fred Coe

  4. Jack

    Does still having a stone in the kidney affect the amount of calcium seen on the 24-hour urine? I had one large calcium oxalate stone removed from the ureter but have another good sized stone in the other kidney that I’m trying to put off treating for a little bit if I can. I don’t want it to grow larger in the meantime, and so had the 24-hr urine done. Ca was 399mg/24hrs, Oxalate was 48mg, and Uric Acid was 876mg. Total volume 2.1L. Wondering if having that stone sitting up there is influencing the urine readings, or if that’s still all coming through the kidneys?

  5. Chris

    I am trying to donate a kidney for a loved one and have a 7 mm stone. I really want to pass the 24 hour urine test. I don’t want to consume anything that might give bad results. How can I optimize my results? I have zero history of stones in myself of in my family.

    • Fredric Coe, MD

      Hi CHris, donation of kidneys by stone formers is a special issue. The transplant center you work with will have a protocol to evaluate your suitability. I would advise you collect the 24 hour urine eating and drinking as you usually do. Special changes you make could make your results look more abnormal! If you indeed have stone forming abnormalities, let your physicians advise you; they have proper skills and work by protocols designed to protect you and your intended recipient. Regards, Fred Coe

  6. Paula

    I am doing a 24 hour collection tomorrow because of erratic parathyroid levels and the incidental finding of kidney stones during a scan of my pancreas. This may seem silly, but I would like to make a special occasion dinner that involves boiling a bottle of red wine down to about 2 cups before simmering with the chicken for 2 hours. Does alcohol really burn off? I was told to avoid alcohol and calcium supplements during the test.

    • Fredric Coe, MD

      Hi Paula, The chicken sounds delicious. Perhaps you might want to collect your 24 hour sample eating a diet more like your usual one, although from the ambitious plan you are perhaps commonly a fine chef. The alcohol is volatile and much will distill off. Be sure your blood for PTH includes a calcium measurement and is fasting. Regards, Fred Coe

  7. Yvonne Posey

    I have pediatricians requesting stone formers profile on a random urine rather than a 24 hour urine. What is your recommendation on this?

    • Fredric Coe, MD

      Hi Yvonne, I know why but unless it is on infants I would try to get a real collection. The cost is the same, the information a lot better. When I owned Litholink we performed a large number of 24 hour urines on kids and the company – no part of LabCorp – still does, so it is not a big deal. Regards, Fred

  8. Denise

    Hello Dr. Coe and Jill Harris,
    What a wonderful web site! Thank you for sharing all this information!! It is all very helpful. I do have a few questions. First, some background: I have a history of idiopathic hematuria (checked out about 7 or 8 years ago), many UTIs (which I self-treat these days with D’Mannose and probiotics to avoid antibiotics–quite successfully). I also have a history (probably irrelevant) of nephritis as a 4-year old. Additionally, I was diagnosed with vulvodynia in 1997 and had my urine tested at the time and had a high oxalate level. I’m now 62. Despite my 2001 diagnosis of CLLeukemia, I’m still at stage zero and generally in good health with all my “healthy eating” and supplements.

    But now I’m dealing with 4+ RBC in my urine, and on reflection I realize I’ve been eating way too many oxalates, as for years now it didn’t seem to matter (little or no pain). Fast forward to the present. Could calcium oxalate crystals be irritating my bladder or urethra enough to cause micrscopic bleeding? I have had an uptick of pain, particularly after urination, with no infection. This morning I had a kidney and bladder ultrasound at a urologist’s office, and the technician said that while I have to wait for the radiology report (two weeks), she didn’t see any stones. I’ve already changed up my diet to reduce oxalates and the mild vulvodynia pain has somewhat subsided. (I was eating whole orange and lemons –with skin– as well as raspberries, nuts, homemade bone broth soup, homemade fermented vegetables, Swiss chard, spinach, and lots and lots of carob.) My question: Do you think I would benefit from a 24-hour urine collection? Do I need to get that ordered from a doctor? And most of all, could crystals be the cause of the bleeding? Do you offer phone consultations? I can be contacted at cllalternatives @ gmail.com (no spaces). Again, thank you for your wonderful site! – Denise

    • Fredric Coe, MD

      Hi Denise, crystals can cause pain and bleeding. A good way to look is through a microscope – your physician can do this or have it done – on morning samples. To look is very inexpensive, and if crystals go with the blood you have the beginnings of an answer. Another is 24 hour urine looking at calcium, oxalate, and all other crystallization potentials. Oxalate alone is unlikely as a cause. Unexplained bleeding will inevitably require a diagnostic evaluation beyond ultrasound. Your urologists knows this. My university has not as yet set up formal telemedicine, so I cannot actually offer proper consultation at this time. Sorry. Regards, Fred Coe

  9. Ray

    My doctor did a 24h urine test which comprised of Creatinine, Sodium, Potassium, Urate and Calcium.
    Which other tests should ideally be done for a calcium oxalate stone former or stone former in general
    to cover all areas?

    Also, I’m now drinking a lot more, as before I was drinking very little , even when exercising intensely
    which is probably the cause of my stones. When doing the collection should you drink the same volume
    as you used to drink previously, which in my case is very little? I don’t want to start the creation of another stone
    even if just for 24h…



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