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Test Code CCLR or LAB818 Creatinine Clearance, Serum and 24 Hr Urine

Important Note

Optimally, the serum specimen should be collected midpoint during the collection period. However, a serum specimen collected up to one week before or after may be acceptable in normal individuals and patients with stable, mild renal disease.

For patients with diseases that actively affect the creatinine level, such as patients on dialysis, a serum sample should be collected as close to the urine collection as possible (+/- 24 hours). It may be necessary to contact the physician to determine the patient's status. If one is questioning whether or not to cancel or reschedule this test, please first check with the chemistry department. 

Profile Information

Test ID   Reporting Name Available Separately Always Performed
CREA Creatinine w/GFR, Serum Y Y
URCRT Creatinine Clearance, 24 Hr Urine Y Y

Specimen Requirements

Patient Preparation:

On the day of the test, the patient is permitted to eat a moderate breakfast. Coffee, tea, or soda should be avoided. Other fluids are encouraged. The patient should avoid vigorous exercise and should be well hydrated before the test is started.
Container Type:
  1. 24-hour urine container

  1. Gold or mint
Optimal Collection Volume: 
  1. Urine - Entire collection
  2. Serum or Plasma - 5 mL
Minimum Volume:
  1. Urine - Entire collection
  2. Serum or Plasma - 1 ml whole blood
Collection Instructions:

Urine

  1. No preservative is preferred, but acid preservatives such as boric, hydrochloric, and acetic are acceptable. Please click the Mayo link for a full list of acceptable preservatives.
  2. Other requirements for the collection
    1. The patient's height and weight
    2. The starting and ending times of the collection.
    3. The 24-hour volume.
  3. Refrigerate the container during the collection period.
  4. Please click the Urine Collection and Patient Instructions for 24-Hour Urine Collection links for additional collection instructions.

Blood

  1. After collection, gently invert the sample 4-5 times.
Specimen Transport:

Refrigerated
Processing Instructions: 
  1. For the urine collection, measure and record the total volume.
  2. Mix the entire urine collection and pour off 2.0 mL into an aliquot.
  3. Spin the urine aliquot.

Specimen Stability

Specimen Type Temperature Time
Urine

Refrigerated

7 days

Room Temperature

2 days

Blood (Serum or Plasma*)

Refrigerated

7 days

Room Temperature

7 days

 

* Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.

Specimen Rejection Criteria

No blood specimen drawn within the 24-hour urine collection

*See the ordering note for details before canceling the test.

Useful For

Measuring the estimated glomerular filtration rate (eGFR).

Methodology

Roche Cobas - Enzymatic colorimetric

Reference Ranges

90-130 ml/min/1.73 m2

Interpretive

CRCL - Clinical & Interpretive: Creatinine Clearance, Serum and 24-Hour Urine (mayocliniclabs.com)

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo, Battle Creek, Paw Paw, South Haven

Sample Retention Time

7 days

CPT Code

82575

LOINC Code

33558-8