Test Catalog

Test Id : CRCL

Creatinine Clearance, Serum and 24-Hour Urine

Useful For
Suggests clinical disorders or settings where the test may be helpful

Estimation of glomerular filtration rate

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

Test Id Reporting Name Available Separately Always Performed
CRTS1 Creatinine with eGFR, S Yes Yes
CRCU Creatinine, U No Yes

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Enzymatic Colorimetric Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Creatinine Clearance

Lists additional common names for a test, as an aid in searching

Creatinine Clearance, Serum and Urine

Specimen Type
Describes the specimen type validated for testing



Necessary Information

1. 24-Hour volume is required.

2. Patient's height in centimeters and weight in kilograms are required.


Question ID Description Answers
VL52 Volume
TM54 Time
W2 Weight
HT1 Height

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Both serum and urine are required. Serum must be collected no earlier than 72 hours before start of urine collection and no later than 72 hours after urine collection is completed.


Specimen Type: Serum

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Centrifuge and aliquot serum into plastic vial.

2. Label specimen as serum.


Specimen Type: Urine

Supplies: Sarstedt 5 mL Aliquot Tube (T914)


Specimen Volume: 5 mL

Collection Instructions:

1. Collect urine for 24 hours.

2. Refrigerate specimen within 4 hours of completion of 24-hour collection.

3. Label specimen as urine.

Additional Information: For multiple collections see Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens

Special Instructions
Library of PDFs including pertinent information and forms related to the test


If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.







50% Acetic Acid


Boric Acid


Diazolidinyl Urea


6M Hydrochloric Acid


6M Nitric Acid


Sodium Carbonate






Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

Serum: 0.5 mL

Urine: 1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred)
Urine Refrigerated (preferred)

Useful For
Suggests clinical disorders or settings where the test may be helpful

Estimation of glomerular filtration rate

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Estimated glomerular filtration rate (eGFR) using serum creatinine alone is calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation:

eGFR = 142 x min(standardized Scr/k,1)alpha x max(Scr/k, 1)-1.200 x (0.9938 x age) x 1.012 (if patient is female)


-age is in years

-Scr is serum creatinine concentration

-k is 0.7 for females and 0.9 for males

-alpha is -0.241 for females and -0.302 for males

-min indicates the minimum of Scr/k or 1

-max indicates the maximum of Scr/k or 1


Use of an estimating or prediction equation to estimate GFR from serum creatinine should be employed for people with CKD and those with risk factors for CKD (diabetes, hypertension, cardiovascular disease, and family history of kidney disease). Reasons given for routine reporting of eGFR with every serum creatinine in adult (18 and over) patients include:

-GFR and creatinine clearance are poorly inferred from serum creatinine alone. GFR and creatinine clearance are inversely and nonlinearly related to serum creatinine. The effects of age and sex further cloud interpretation.

-Creatinine is commonly measured in routine clinical practice. Albuminuria (>30 mg/24 hour or urine albumin to creatinine ratio >30 mg/g) may be a more sensitive marker of early kidney disease, especially among patients with diabetic nephropathy. However, there is poor adherence to guidelines that suggest annual urinary albumin testing of patients with known diabetes. Therefore, if a depressed eGFR is calculated from a serum creatinine measurement, it may help providers recognize early CKD and pursue appropriate follow-up testing and therapeutic intervention.

-Monitoring kidney function (by GFR or creatinine clearance) is essential once albuminuria is discovered. Estimated GFR is a more practical means to closely follow changes in GFR over time, when compared to direct measurement using methods such as iothalamate clearance.

-The CKD-EPI equation does not require weight or height variables. From a serum creatinine measurement, it generates a GFR result normalized to a standard body surface area (1.73 m[2]) using sex and age. Unlike the Cockcroft-Gault equation, height and weight, which are often not available in the laboratory information system, are not required. The 2021 CKD-EPI Cr equation does not require race, so eGFR values for both African American and non-African American populations are no longer reported. The new 2021 CKD-EPI eGFR values cannot be directly compared to the previous 2009 CKD-EPI Cr eGFR values, which were separately reported for African American and non-African American populations.


The Kidney Disease: Improving Global Outcomes (KDIGO) CKD work group clinical practice guidelines,(1) as further defined by the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) commentary,(2) provided recommendations for reporting and interpretation of serum creatinine and eGFR, which were revised after development of a refit CKD-EPI Creatinine eGFR equation in 2021 that does not require a mathematical adjustment based on race:

1.4.3: Evaluation of GFR

- We recommend using serum creatinine and GFR estimating equation for initial assessment.

- We suggest using additional tests (such as cystatin C or a clearance measurement) for confirmatory testing in specific circumstances when eGFR based on serum creatinine is less accurate.

- We recommend that clinicians:

Use a GFR estimating equation to derive GFR from serum creatinine (eGFRcreat) rather than relying on the serum creatinine concentration alone.

Understand clinical settings in which eGFR creat is less accurate.

- We recommend that clinical laboratories should:

Measure serum creatinine using a specific assay with calibration traceable to the international standard reference materials and minimal bias compared to isotope-dilution mass spectrometry (IDMS) reference methodology.

Report eGFRcreat in addition to the serum creatinine concentration in adults and specify the equation used whenever reporting eGFRcreat.

Report eGFRcreat in adults using the 2021 CKD-EPI creatinine equation.


When reporting serum creatinine:

We recommend that serum creatinine concentration be reported and rounded to the nearest whole number when expressed as standard international units (mmol/L) and rounded to the nearest 100th of a whole number when expressed as conventional units (mg/dL).


When reporting eGFRcreat:

-We recommend that eGFRcreat should be reported and rounded to the nearest whole number and relative to a body surface area of 1.73 m(2) in adults using the units mL/min/1.73 m(2).

-We recommend eGFRcreat levels less than 60 mL/min/1.73 m(2) should be reported as "decreased". We suggest measuring GFR using an exogenous filtration marker under circumstances where more accurate ascertainment of GFR will impact treatment decisions


Creatinine Clearance:

Creatinine is derived from the metabolism of creatine from skeletal muscle and dietary meat intake and is released into the circulation at a relatively constant rate. Thus, the serum creatinine concentration is usually stable. Creatinine is freely filtered by glomeruli and not reabsorbed or metabolized by renal tubules. Therefore, creatinine clearance can be used to assess GFR. However, approximately 15% of excreted urine creatinine is derived from proximal tubular secretion. Because of the tubular secretion of creatinine, creatinine clearance typically overestimates true GFR by 10% to 15%.


Creatinine clearance is usually determined from measurement of creatinine in a 24-hour urine specimen and from a serum specimen obtained during the same collection period. However, shorter time periods can be used. A key consideration is accurate timing and collection of the urine sample. Creatinine clearance normalized to body surface area is calculated by the equation:

2.54 cm=1 inch

1 kg=2.2 pounds (lbs)

Patient surface area (SA)=wt (kg)(0.425) X ht (cm)(0.725) X 0.007184



Urine conc (mg/dL) x 24 hr urine volume (mL)



Uncorr creat clear=


1440 minutes




Serum creat (mg/dL)



















Urine conc (mg/dL) x 24 hr urine volume (mL)


1.73 m(2)

Patient SA

Corr creat clear=


1440 minutes


Serum creat (mg/dL)




Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.



0-18 years: Not established

19-75 years: 77-160 mL/min/body surface area (BSA)

> or =76 years: Not established



0-17 years: Not established

18-29 years: 78-161 mL/min/BSA

30-39 years: 72-154 mL/min/BSA

40-49 years: 67-146 mL/min/BSA

50-59 years: 62-139 mL/min/BSA

60-72 years: 56-131 mL/min/BSA

> or =73 years: Not established



Reported in units of mg/dL




0-11 months: 0.17-0.42 mg/dL

1-5 years: 0.19-0.49 mg/dL

6-10 years: 0.26-0.61 mg/dL

11-14 years: 0.35-0.86 mg/dL

> or =15 years: 0.74-1.35 mg/dL



0-11 months: 0.17-0.42 mg/dL

1-5 years: 0.19-0.49 mg/dL

6-10 years: 0.26-0.61 mg/dL

11-15 years: 0.35-0.86 mg/dL

> or =16 years: 0.59-1.04 mg/dL


Estimated glomerular filtration rate (eGFR)

> or =18 years old: > or =60 mL/min/BSA

eGFR calculated using the 2021 CKD-EPI creatinine equation

Note: eGFR results will not be calculated for patients younger than 18 years old.

Provides information to assist in interpretation of the test results

Decreased creatinine clearance indicates decreased glomerular filtration rate (GFR). This can be due to conditions such as progressive kidney disease or result from adverse effect on renal hemodynamics that are often reversible, including drug effects or decreases in effective renal perfusion (eg, volume depletion, heart failure).


Increased creatinine clearance is often referred to as hyperfiltration and is most commonly seen during pregnancy or in patients with early diabetes mellitus, before diabetic nephropathy has occurred. It may also occur with large dietary protein intake.


A major limitation of creatinine clearance is that its accuracy worsens in relation to the amount of tubular creatinine secretion. Often as GFR declines, the contribution of urine creatinine from tubular secretion increases, further increasing the discrepancy between true GFR and measured creatinine clearance.


Estimated GFR:

According to the Kidney Disease: Improving Global Outcomes (KDIGO) CKD work group, chronic kidney disease (CKD) is defined as the abnormalities of kidney structure of function, present for more than 3 months, with implications for health.(1,2) CKD should be classified by cause, GFR category, and albuminuria category.(1,2)


KDIGO guidelines provide the following GFR categories(1,2):




GFR mL/min/1.73 m(2)


Normal or high



Mildly decreased

60 to 89


Mildly to moderately decreased

45 to 59


Moderately to severely decreased



Severely decreased



Kidney failure



*In the absence of evidence of kidney damage, neither G1 nor G2 fulfill criteria for CKD.

Urinary albumin excretion can also be used to further subdivide CKD stages.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

One of the major limitations of creatinine clearance is erroneous results due to incomplete urine collections. Accurate results depend upon a complete and accurately timed collection.


Result can be falsely decreased in patients with elevated levels of N-acetyl-p-benzoquinone imine (NAPQI, a metabolite of acetaminophen), N-acetylcysteine, and metamizole.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Inker LA, Astor BC, Fox CH, et al: KDOQI US commentary on the 2012 KDIGO clinical practice guideline for the evaluation and management of CKD. Am J Kidney Dis. 2014 May;63(5):713-35. Doi: 10.1053/j.ajkd.2014.01.416

2. National Kidney Foundation. KDOQI Clinical Practice Guideline for Diabetes and CKD: 2012 Update. Am J Kidney Dis. 2012 Nov;60(5):850-886. doi: 10.1053/j.ajkd.2012.07.005. Erratum in: Am J Kidney Dis. 2013 Jun;61(6):1049

3. Inker LA, Perrone RD: Assessment of kidney function. In: Sterns RH, Forman JP, eds. UpToDate; 2021. Updated July 1, 2022. Accessed July 13, 2022. Available at www.uptodate.com/contents/assessment-of-kidney-function

4. Kasiske BL, Keane WF: Laboratory assessment of renal disease: clearance, urinalysis, and renal biopsy. In: Brenner BM, ed. The Kidney. 6th ed. WB Saunders Company; 2000:1129-1170

5. Delaney MP, Lamb EJ: Kidney disease. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:1256-1323

6. Miller WG, Kaufman HW, Levey AS, et al: National Kidney Foundation Laboratory Engagement Working Group Recommendations for implementing the CKD-EPI 2021 Race-Free Equations for Estimated Glomerular Filtration Rate: Practical guidance for clinical laboratories. Clin Chem. 2022 Mar 31;68(4):511-520. doi: 10.1093/clinchem/hvab278

7. Inker LA, Eneanya ND, Coresh J, et al: Chronic Kidney Disease Epidemiology Collaboration. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021 Nov 4;385(19):1737-1749. doi: 10.1056/NEJMoa2102953

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 2 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
CRCL Creatinine Clearance 58446-6
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
CRE_U Creatinine, U 20624-3
TM54 Time 13362-9
VL52 Volume 3167-4
CRCL1 Creatinine Clearance 12195-4
CRTSA Creatinine, S 2160-0
EGFR1 Estimated GFR (eGFR) 2160-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
File Definition - Result ID 2022-08-23