Creatinine

Preparation

Fasting. Avoid intense exercise the day before (may transiently raise creatinine). Report creatine/protein supplements.

Turnaround

24 h

Reference values

Reference depends on sex, age, and muscle mass — follow your report; eGFR and urinalysis help if abnormal.

FAQ

Why can creatinine be high with healthy kidneys?

Transient rises occur after exercise, dehydration, or high muscle mass. Repeat testing and eGFR clarify the picture.

Do I need a 24-hour urine collection if creatinine is high?

Not always: clinicians may order eGFR, urine albumin/creatinine ratio, or renal ultrasound. A 24-hour collection is case-dependent.