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SOP

Serum Creatinine Testing

SOP for quantitative measurement of creatinine to assess glomerular filtration rate (GFR).

Last verified 1 month ago 1 min read Clinical Chemistry Renal Metabolic #egfr #renal-function #creatinine #clinical chemistry #jaffe #enzymatic
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Version
1.0
Effective
Aug 29, 2026
Reviewed
Aug 29, 2026
Department
Clinical Chemistry
Principle

Enzymatic methods are highly specific and avoid the non-specific interference (e.g., from proteins, glucose, ketones) common in the traditional Jaffe reaction.

Standard Operating Procedure: Serum Creatinine

1. Purpose: Assess renal function and calculate eGFR.

2. Specimen: Serum or plasma.

3. Reagents: Enzymatic creatinine reagent (preferred) or Jaffe (alkaline picrate) kinetic reagent.

4. Procedure (Enzymatic):

  • Creatinine is hydrolyzed by creatininase to creatine.
  • Creatine is converted to sarcosine and urea.
  • Sarcosine is oxidized to glycine, formaldehyde, and H2O2.
  • H2O2 reacts with a chromogen to form a colored complex measured at 550 nm.

5. Reference Ranges

  • See the Reference Ranges panel below for sex-specific adult reference intervals.

6. QC: Run 2 levels of control daily.

Reference Ranges

Browse all ranges

0.74–1.35 mg/dL

0.59–1.04 mg/dL

Frequently Asked Questions

The Jaffe method suffers from positive interference by non-creatinine chromogens (e.g., ketoacids, cephalosporins), while enzymatic methods are highly specific.