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.


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Fredric Coe, MDMelindaLynnjharrisLaura Recent comment authors

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My menstruation began the same day my urine test arrived. Should I wait for my period to end, or should I do the urine test as soon as possible?

Fredric Coe, MD

Hi Melinda, it is reasonable to wait. Easier, too. Regards, Fred Coe


Is it ok to have sex during a collection?


What happens if I miss 1 urine do I have to start all over again


Hello. What is normal PH level should be in 24 hour urine collection? If 7 is neutral, should I strive it to be close to 7? Mine is 6.961. My second question is regarding Ca 24. Mine is 368. Does it mean I excrete too much calcium it and that is why I have osteoporosis? Thank you.

Fredric Coe, MD

Hi Birute, The usual urine pH is 6; yours is high. Likewise your urine calcium. You may have idiopathic hypercalciuria, a cause of bone disease and stones, and need to be sure – your physicians do this – and treat it properly – high diet calcium, low diet sodium, meds if needed. Regards, Fred Coe

John Smithson
John Smithson

Thank you for an informative article. I am considering having a kidney stone analyzed and having a 24-hour urine test but am wondering about the costs. I can’t find any costs anywhere on the Internet. Can you give me a rough idea of the cost?

Fredric Coe, MD

Hi John, Price in the US is strange. If you have Medicare, common commercial vendors – not hospitals! – should furnish the testing for about $200.00 per 24 hour urine. If not, everything depends on your insurance plan, but your out of pocket cost should be in about that same range more or less. For stone analysis, prices run a lot lower – perhaps $50.00 to the patient, and insurance usually pays most of it. These are my own observations, and who knows what charges can be from one place to another. Regards, Fred Coe

Michael Millsap
Michael Millsap

Dr. Coe, you had offered me the opportunity to share my labs with you in hopes of some insight as to what direction I might take. Hopefully, this is the correct place to add them? Actions taken after the first sample: drastic reduction in nut intake (my weakness), consistent H2O intake of min. 3 liters daily, addition of 1000 mg of CA via supplementation, Na intake reduced. Historically, I am a Ca Ox stone builder. I cannot adequately express my gratitude for your willingness to selflessly help others like myself suffering from kidney stones! 4/6/18 8/12/18 Vol 3.61 3.31 SSCaOx… Read more »

Fredric Coe, MD

Hi Michael, The two urines cannot be compared because the creatinine excretions vary between 2187 and 1576; because these reflect muscle mass, one of them is wrong – your muscle mass did not change that much in 4 months. Both show high urine volumes, the second one a very low pH – are you sure your stones do not contain uric acid?? – The oxalate did fall even if I adjust for the creatinine, but only from 44 to 38 (2187/1576 = 1.3 as a multiplier to bring the second urine to the first). Urine sodium thus adjusted rose, as… Read more »

Michael Millsap
Michael Millsap

Dr. Coe, I have attached my most recent results after you suggested that the creatinine excretions were awry. It appears the first lab was not accurate, so only the most recent 2 are below. On the lab from 4/6/18 (not shown) Urine Ca was 206 and I was directed to supplement with Ca, which I did 100mg/day. Now it appears the Ca is high Lab 2 (8/12/18) showed urine citrate of 364. I was directed to increase citrate, so now take lemon juice in my 3 liters of daily water intake. That appears to have improved. I would very much… Read more »

Fredric Coe, MD

Hi Michael, Note the sodium is higher in the urine with more sodium (145 181); higher sodium raises urine calcium loss; even allowing for urine creatinine, Ca/cr24 went up with urine sodium. Urine sodium is basically diet sodium integrated over several days. So the message is lower your diet sodium. A fair goal is below the tolerable upper limit for the US of 2300 mg/d – 100 mEq/d. The citrate went up, and perhaps the lemon juice did that. But lemon juice is bad for tooth enamel so you might want to use more fruits and veggies. I am suspicious… Read more »

Michael Millsap
Michael Millsap

Dr. Coe, many thanks for your time and focus. I will digest this, and work on limiting sodium.

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