Creatinine

Background

• Byproduct of muscle metabolism; freely filtered by the kidney
• Primary marker of renal function in the ED

Normal Values

• Normal: 0.6-1.2 mg/dL (varies by age, sex, muscle mass)

Interpretation

• Elevated creatinine indicates decreased renal clearance; may lag 24-48 hours behind acute injury
• A "normal" creatinine in elderly or low-muscle-mass patients may actually represent significant renal impairment
• Acute rise of >0.3 mg/dL from baseline or 1.5x baseline defines acute kidney injury by KDIGO criteria
• Drugs that increase creatinine without true renal injury: trimethoprim, cimetidine, cobicistat

See Also

• Acute kidney injury
• BUN
• GFR
• BMP