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Urine Creatinine, 24-Hour

Total creatinine in all the urine you pass over 24 hours. It mostly reflects muscle mass and helps show whether a 24-hour collection was complete.

AI-verified against cited sources. Awaiting expert reviewAlso called 24h UCr, UCr 24hLOINC 2162-6

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The usual range for 24-Hour Urine Creatinine depends on sex. Choose female or male above to see where you stand.

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What it is

Creatinine is a waste product made when muscle breaks down. Your kidneys filter it from your blood and it leaves in your urine. A 24-hour urine creatinine adds up all of it you pass in a day. It is usually measured alongside other 24-hour urine tests, or compared with a blood creatinine to estimate how well your kidneys clear waste (creatinine clearance).

Why it matters

On its own this is not a kidney test. How much creatinine you pass depends mostly on how much muscle you have, so men usually pass more than women and the amount tends to fall with older age. Clinicians use it to judge whether a 24-hour collection was likely complete, because missed urine makes every total on the report too low. They also use it to work out creatinine clearance.

If it’s low

A low total most often means some urine was missed during the collection. It can also be seen with low muscle mass, older age, or reduced kidney function. Your clinician will compare it with your age, sex and body size before deciding what it means.

Common causes

  • Missed or discarded urine during the 24 hours (an incomplete collection)
  • Low muscle mass, including muscle loss with older age
  • Reduced kidney function, which is linked to lower daily creatinine in urine
  • Lower body weight

What can help

  • Ask whether the collection could have been incomplete and whether it should be repeated
  • Ask how your age, muscle mass and kidney function were considered when reading the result

If it’s high

A higher total most often reflects a larger or more muscular body, a recent meal with a lot of cooked meat, or creatine supplements. It can also happen if more than 24 hours of urine was collected. A high result on its own is not usually a sign of a kidney problem.

Common causes

  • Higher muscle mass or larger body size
  • A lot of cooked meat in the day before or during the collection
  • Creatine supplements
  • Collecting more than 24 hours of urine, or saving the first urine of the start day

What can help

  • Ask your clinician whether your diet or supplements could explain the result
  • If the test is repeated, follow the collection instructions closely

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex and age. Choose women or men to see the one that applies.

Children and teens 4 ranges

See 24-Hour Urine Creatinine by age and sex, with the U.S. survey numbers where they exist.

What can affect your result

  • Sex: men usually pass more creatinine than women
  • Age: totals tend to be lower in older adults
  • Muscle mass and body size
  • Cooked meat in the diet and creatine supplements
  • Kidney function
  • Whether the 24-hour collection was complete and timed correctly
  • A missed collection or lost urine makes the total too low; saving the first urine of the day you start, or collecting past 24 hours, makes it too high.
  • Cooked meat can temporarily raise creatinine, so some labs ask you to avoid meat for 24 hours before the test.
  • Creatine supplements can raise urine creatinine.
  • Urine that is not kept refrigerated during the collection can give unreliable results.

Collect every drop of urine for 24 hours. Empty your bladder at the start time and throw that urine away, then collect all urine for the next 24 hours, including one last sample at the end. Keep the container cool. Reflects the single 24-hour period collected. Long-term changes in muscle mass or kidney function move it slowly.

Questions you could ask

  • Which other results on this report depend on the collection being complete?
  • Could my diet or any supplements, such as creatine, explain this result?
  • Could more than 24 hours of urine have been collected?
  • Could some urine have been missed during my collection, and should we repeat it?
  • How do my age, muscle mass and kidney function fit with this result?

Questions people ask

Why does my lab want all my urine for 24 hours?

Urine gets more or less concentrated through the day, so a single sample cannot give a reliable daily total. If some urine is missed, the totals for every substance on the report come out too low.

If my 24-hour creatinine is in range, are my kidneys healthy?

Not by itself. The total depends mostly on muscle mass. Kidney function is judged with blood creatinine, eGFR, or a creatinine clearance that compares blood and urine, along with other tests.

How do I convert mg/24 h to mmol/24 h?

Multiply mg/24 h by 0.00884. For example, 1,500 mg/24 h is about 13.3 mmol/24 h. To go the other way, multiply mmol/24 h by 113.1.

Show the science and sources

Units

  • 1 mg/24 h = 1 mg/24 h
  • 1 mg/24 h = 0.001 g/24 h
  • 1 mg/24 h = 0.00884 mmol/24 h
  • 1 mg/24 h = 8.84 µmol/24 h

Open the 24-Hour Urine Creatinine unit converter

Is a change real?

24-Hour Urine Creatinine naturally varies about 11% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 34% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).

For clinicians and researchers

Creatinine comes from muscle creatine and is filtered at the glomerulus, with some tubular secretion, so 24-hour excretion tracks muscle mass and, to a lesser extent, diet, age, sex, ethnicity and kidney function. In early CKD, 24-hour creatinine excretion falls as measured GFR falls (Tynkevich 2014). Equations that predict 24-hour creatinine from age, sex, weight and ethnicity (for example Cockcroft-Gault, Walser, Goldwasser, Rule and CKD-EPI) have been proposed to judge whether a collection is complete (Jedrusik 2019). Expressing the result per kilogram of body weight (mg/kg/24 h) is common for that purpose and is not encoded here because it needs body weight. Reference intervals differ by lab: ARUP publishes age- and sex-specific intervals from age 3, while Mayo Clinic Laboratories lists one adult interval per sex (930-2955 mg/24 h for men, 603-1783 mg/24 h for women) and none under 18. Mayo lists a colorimetric method and ARUP quantitative spectrophotometry. Creatinine clearance (urine creatinine x urine volume / serum creatinine x time) overestimates true GFR because some creatinine is secreted.

LOINC 2162-6 (primary), 14684-5, 20624-3. Specimen: urine-24h.

Sources

  1. Creatinine, Urine - per 24h (test 0020473), ARUP Laboratories
  2. CRT24: Creatinine, 24 Hour, Urine (Mayo Clinic Laboratories catalog, mirrored at testcatalog.org), Mayo Clinic Laboratories
  3. Creatinine Test, MedlinePlus (U.S. National Library of Medicine)
  4. Decrease in Urinary Creatinine Excretion in Early Stage Chronic Kidney Disease, PLoS ONE 2014;9 (2014)
  5. Performance of 24-hour urinary creatinine excretion-estimating equations in relation to measured 24-hour urinary creatinine excretion in hospitalized hypertensive patients, Scientific Reports 2019;9 (2019)
  6. Creatinine (PubChem CID 588), National Center for Biotechnology Information
  7. LOINC codes verified with the NLM Clinical Tables LOINC search, U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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