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Creatinine Clearance (24-Hour Urine)

Compares creatinine in a 24-hour urine collection with creatinine in your blood to estimate how much blood your kidneys clear each minute.

AI-drafted. Awaiting verificationAlso called Ccr, CCrLOINC 2164-2

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The usual range for Creatinine Clearance 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 from muscle that your kidneys remove from the blood. For this test you collect all of your urine for 24 hours and have a blood sample taken close to that time. The lab compares how much creatinine ended up in the urine with how much is in your blood. The result is the volume of blood cleared of creatinine each minute, which gives an estimate of how well your kidneys filter. Some labs print the raw number (mL/min) and others adjust it to a standard body size of 1.73 m² (mL/min/1.73 m²), so check which one your report uses.

Why it matters

Creatinine clearance gives another way to look at kidney filtration (GFR) using your own urine, not just a formula. KDIGO suggests it only when a directly measured GFR is not available and the blood-based eGFR from creatinine plus cystatin C is thought to be inaccurate. The catch is the 24-hour collection, which is easy to get wrong. In a review of 23 studies, KDIGO found that it differed from measured GFR by about 25% on average.

If it’s low

A lower clearance can mean your kidneys are filtering less blood than expected, but it is often the collection that falls short. Missing even a few samples can pull the result down. Values also fall gradually with age. One result is not enough to say anything about kidney disease, and your clinician can put it in context with your eGFR and urine tests.

Common causes

  • An incomplete 24-hour urine collection (the most common reason)
  • Dehydration or a recent illness
  • Getting older, since normal values decrease with age
  • Kidney conditions, including damage to the kidney's filters or to its tubules
  • Too little blood flow to the kidneys, for example from heart failure
  • A blockage in the bladder's outflow

What can help

  • Ask whether your collection was complete and whether it should be repeated
  • Ask about a cystatin C test or an eGFR that uses both creatinine and cystatin C
  • Ask your clinician to review your medicines and supplements, and don't stop any on your own
  • Keeping blood pressure and blood sugar in the range your clinician recommends supports kidney health

If it’s high

A higher clearance means more creatinine is leaving in your urine compared with the amount in your blood. Young, healthy adults often have values at the upper end of the range. A high value can also come from how the test was done, since the kidneys release a little creatinine into the urine on their own and a collection that ran too long can overstate the result.

Common causes

  • Younger age, since clearance is highest in young adults
  • A urine collection that ran longer than 24 hours or a time that was recorded wrongly
  • Creatinine released by the kidney tubules, which makes clearance run above true filtration
  • Pregnancy, when kidney filtration normally rises

What can help

  • Ask your clinician whether the collection was complete and timed correctly
  • Ask whether a blood-only eGFR or a cystatin C test gives a consistent picture

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.

See Creatinine Clearance by age and sex, with the U.S. survey numbers where they exist.

What can affect your result

  • How complete and accurately timed the 24-hour collection is
  • Muscle mass, diet, and creatine supplements
  • Medicines that change how the kidney handles creatinine
  • Age: normal values decrease with advancing age
  • Sex: labs print different ranges for males and females
  • Body size, which is why some labs adjust the result to 1.73 m² of body surface area
  • Whether your lab reports the raw (mL/min) or the body-size-adjusted (mL/min/1.73 m²) value
  • Dehydration or illness during the collection
  • Missed urine during the 24 hours makes the result look lower than your true kidney function. Collecting for longer than 24 hours, or recording the time wrongly, can make it look higher. KDIGO calls this test highly prone to error from under- or over-collection.
  • Creatinine production varies with muscle mass, diet and creatine supplements, so people with unusually low or high muscle mass can get a misleading number.
  • Kidney tubules also release a little creatinine into the urine, so clearance tends to run above the true filtration rate. Medicines that block this release, such as trimethoprim, can raise blood creatinine and lower the result without a true drop in kidney function.
  • Illness or dehydration during the collection can change the result for that day.
  • Mayo Clinic Laboratories needs the 24-hour volume, your height and your weight to report the body-size-adjusted value.
  • Tell your clinician about all medicines and supplements. MedlinePlus notes that some antibiotics and stomach acid medicines can affect the test, and you should not stop any medicine without talking to your clinician first.

A full 24-hour urine collection plus a blood sample. Follow your lab's instructions: ARUP asks for the urine to be kept refrigerated during collection and for the blood to be drawn within 24 hours before or after it, and Mayo Clinic Laboratories allows the blood within 72 hours either side. Reflects kidney filtration over the collection day. Lasting changes in kidney function are judged over at least 3 months.

When to talk to a clinician

Talk with a clinician if your result is below the range on your report, especially if your eGFR is also below 60. KDIGO lists an eGFR below 30 among the reasons to see a kidney specialist. Contact a clinician soon if you notice much less urine than usual, swelling in your legs or feet, nausea or vomiting, or severe tiredness. If your lab flagged the result as urgent, follow its instructions.

Questions you could ask

  • Which unit does this lab report, and was the result adjusted for my body size?
  • How does this result compare with my eGFR?
  • Could a long or mistimed urine collection explain this result?
  • Does this agree with my eGFR?
  • Was my 24-hour collection complete, and should we repeat it?
  • Would a cystatin C test, or an eGFR that uses both creatinine and cystatin C, give a clearer picture?

Questions people ask

Is creatinine clearance the same as eGFR?

No. Creatinine clearance is measured from your own 24-hour urine and a blood sample. eGFR is calculated from a blood test (creatinine, and sometimes cystatin C) plus your age and sex, with no urine needed. Both estimate how well your kidneys filter, but they can differ noticeably. Because a 24-hour collection is easy to get wrong, KDIGO suggests it only when more accurate options are not available.

What if I miss some of the urine during the 24 hours?

Missing urine makes the result look lower than your true kidney function, and collecting for longer than 24 hours can make it look higher. If you think you missed a sample or the timing was off, tell the lab or your clinician, who may suggest repeating the collection.

Why do some labs report mL/min and others mL/min/1.73 m²?

mL/min is the clearance for your own body. mL/min/1.73 m² adjusts it to a standard body size using your height and weight, so people of different sizes can be compared. Mayo Clinic Laboratories asks for height and weight for this reason. The two numbers are close for an average-sized adult but are not interchangeable, so compare your result with the range in the same unit.

Show the science and sources

Units

  • 1 mL/min = 1 mL/min
  • 1 mL/min = 1 mL/min/1.73 m²
  • 1 mL/min = 0.01667 mL/s

Open the Creatinine Clearance unit converter

For clinicians and researchers

Clearance is calculated as (urine creatinine × urine flow rate) ÷ serum creatinine, which equals urine creatinine × urine volume ÷ (serum creatinine × collection minutes). The body-size-adjusted result multiplies this by 1.73 ÷ body surface area in m². Creatinine is freely filtered but also secreted by the proximal tubule, which tends to push measured clearance above true GFR, while incomplete or over-long collections push it either way. KDIGO 2024 (Practice Point 1.2.2.8) notes that, in a systematic review of 23 studies, measured creatinine clearance had a mean bias of 25% against measured GFR, with errors in both directions, so it did not reach sufficient accuracy. In the AASK pilot, 25% of participants had a 24-hour measured creatinine clearance at least 18% below measured GFR and another 25% had one at least 23% above. If used, KDIGO says collections should ideally be supervised. The Cockcroft-Gault 'creatinine clearance' is a separate estimating equation that uses no urine (LOINC lists it under different codes) and is not what this marker holds. Reference intervals differ in unit as well as value: Labcorp and MedlinePlus give raw mL/min (males 97–137, females 88–128), while Mayo Clinic Laboratories reports body-size-adjusted values with a male range of 77–160 for ages 19 to 75 and female ranges that fall from 78–161 at 18 to 29 to 56–131 at 60 to 72. Because the two units cannot be converted without the person's body surface area, this catalog treats them as different rows and does not convert between them.

LOINC 2164-2 (primary), 12195-4. Specimen: calculated.

Sources

  1. CRCL - Creatinine Clearance, Serum and 24-Hour Urine, Mayo Clinic Laboratories (via the Schneck Medical Center test catalog)
  2. Creatinine Clearance, Urine (test 0020474), ARUP Laboratories
  3. Pediatric Testing Reference Ranges (includes Creatinine Clearance, test 003004), Labcorp
  4. Creatinine clearance test, MedlinePlus (National Library of Medicine)
  5. ABIM Laboratory Test Reference Ranges, American Board of Internal Medicine (2026)
  6. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)

AI-drafted. Awaiting verification. Last reviewed 2026-10-03. How we build and check these pages.

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