Creatinine w/ eGFR

Alternative Names
  • Creatinine Clearance (calculation)
  • eGFR calculation

Test Code: 4541

CPT: 82565
Tests Included Creatinine
Use Measurements of creatinine are used in the diagnosis and treatment of renal disease.
Clinical Utility Serum creatinine measurements prove useful in evaluation of kidney glomerular function and in monitoring renal dialysis. However, the serum level is not sensitive to early renal damage and responds more slowly than blood urea nitrogen (BUN) to hemodialysis during treatment of renal failure. Both serum creatinine and BUN are used to differentiate prerenal and postrenal (obstructive) azotemia.

Serum creatinine varies with the subject's age, body weight, and sex. It is sometimes low in subjects with relatively small muscle mass, cachetic patients, amputees, and in older persons. A serum creatinine level that would usually be considered normal does not rule out the presence of impaired renal function.

An increase in serum BUN without concomitant increase of serum creatinine is key to identifying prerenal azotemia. With postrenal azotemia, both serum BUN and creatinine rise, but the rise is disproportionately greater for BUN.
Intended Patient Population 18+ and Older Adult Males & Females
Patient Preparation None Specified
Sample Serum, Plasma
Tube Red, Green, Tiger
Volume 4mL Whole Blood (1mL Serum/Plasma)
Min Sample Volume 0.1 mLs
Reference Ranges CREA - M ≥ 18 yrs old; 0.70-1.30 mg/dL
CREA - F ≥ 18 yrs old; 0.60-1.20 mg/dL
eGFR - M & F ≥ 18 yrs old; ≥ 60 mL/Min/1.73m^2
Analytical Measurement Range 0.20-30.00 mg/dL
Critical Values ≥ 10.0 mg/dL
Units mg/dL
Test Methodology Quantitative Enzymatic
Test Turnaround Time 1 Day
Limitations Creatinine ratios to urea nitrogen can be affected by reduced renal blood flow. Cephalosporin antibiotics can lead to significant false-positive values if samples are drawn within four hours of a dose.2 Ceatinine is not reliable in the presence of cefoxitin therapy for several renal disease. Lipemia, hemolysis, and bilirubin may interfere.3,4
Shipping Requirements Refrigerated
Specimen Stability 7 Days RT
7 Days RF
Reject Criteria Gross Hemolysis
Laboratory Developed Test (LDT) Yes
CMS Guidance None
  1. Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1999
  2. Durham SR, Bignell AH, Wise R. Interference of cefoxitin in the creatinine estimation and its clinical relevance. J Clin Pathol. 1979 Nov; 32(11):1148-1151. PubMed 512029
  3. Bowers LD, Wong ET. Kinetic serum creatinine assays. II: A critical evaluation and review. Clin Chem. 1980 Apr; 26(5):555-561.
  4. Soldin SJ, Henderson L, Hill JG. The effect of bilirubin and ketones on reaction rate methods for the measurement of creatinine. Clin Biochem. 1978 Jun; 11(3):82-86.

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