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Creatinine Clearance, Blood and Urine

Test Codes

Adult Specimens: EPIC: LAB5442, Beaker: CRECL, Pediatric Specimens: EPIC: LAB5443, Beaker: CRCLP, Antrim: 19643

Department

Chemistry

Instructions

• Collection must include blood and urine specimens.
• The patient should be on a low protein diet (less than 75 grams) for two days prior to the test.
• The patient should also be well hydrated during the test.
• Submit patient height (cm) and weight (kg) for children (less than 18 years of age).
• Please refer to the Specimen Collection Manual for instructions on 24-Hour Urine Collection:
  • Urine 24-Hour Collection - Inpatient
  • Urine 24-Hour Collection - Outpatient
  • Urine 24-Hour Collection - Outreach

Specimen Collection Criteria

Collect: Blood AND Urine specimens.

• Blood: One Gold-top SST tube.
• Urine: 24-hour urine or timed specimen with no preservative.
• Blood specimen must be collected within the time period from 24 hours prior to the start of urine collection thru 24-hours post completion of the urine collection.
• Refer to the table of Urine Preservative Options when multiple tests are requested.
• Keep 24-hour urine specimen iced or refrigerated during collection.
• Include start and end dates and times for the collection period on the specimen container.

Urine Preservative Options
No Preservative	6N Hydrochloric Acid	Boric Acid (10g)	Sodium Carbonate	50% Acetic Acid
PREFERRED	Acceptable	Acceptable	Acceptable	Acceptable

Physician Office/Draw Specimen Preparation

• Let SST specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection. (Minimum: 0.5 mL)
• Maintain urine specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Centrifuged SST tube and entire 24-hour or timed urine collection, refrigerated (2–8°C or 36–46°F).

Rejection Criteria

• Moderate to grossly hemolyzed serum specimens.
• Red-top tubes with serum not separated from cells within two hours of collection.
• Specimens not collected and processed as indicated.

In-Lab Processing

• Let SST specimens clot 30-60 minutes. Centrifuge SST tubes or Microtainers^® to separate serum from cells. Deliver immediately to the appropriate testing station.
• Measure total volume of 24-hour or timed urine specimen. Record total volume and collection start and end dates and times in the LIS system. Aliquot a minimum of 10.0 mL from the well-mixed 24-hour or timed urine collection.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gel
Room temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gel
Room temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Urine Specimens
Room temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): 4 days
Frozen (-20°C/-4°F or below): For longer storage.

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days (Royal Oak and Troy store an aliquot for 30 days.)

Laboratory

Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory

Grosse Pointe Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory
Troy Chemistry Laboratory
Wayne Main Laboratory

Performed

Sunday – Saturday.
Results available within 24 hours. 

Reference Range

Creatinine Clearance: 70-140 mL/min.

Test Methodology

Spectrophotometry.

Interpretation

• Creatinine clearance may be decreased in patients with:
  1. decreased renal blood flow due to congestive heart failure, shock, hemorrhage or dehydration.
  2. intrinsic renal disease such as nephrotic syndrome, glomerulonephritis, pyelonephritis or acute tubular disease.
  3. post-renal obstruction to urine flow.
  4. other causes such as multiple myeloma, adrenocortical hypofunction, hepatic failure, eclampsia and preeclampsia.
• Creatinine clearance can be increased in pregnancy or in patients with high cardiac output, high protein diet, anemia, hypercatabolic states, and with exercise. Value decreases with advance in age.

Clinical Utility

Creatinine clearance is a renal function test used to estimate glomerular filtration rate (GFR).

CPT Codes

82575
LOINC:  2164-2

Contacts

Last Updated

11/2/2023