Creatine, 24-Hour Urine

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Turnaround Time: 3 - 6 days
CPT Code:


Test Type: 2 mL aliquot Urine (24-hour), frozen
Reference Range:

Male: 0-40 mg/24 hours; female: 0-80 mg/24 hours


Determine creatinuria; increased urine creatine values may be obtained from diseases that reduce muscle mass, including fasting, muscular dystrophy, poliomyelitis, atrophy, inflammatory destructive muscle disease as polymyositis, hyperthyroidism, as well as corticosteroid induced myopathy.

Creatine is endogenously synthesized in the kidney, liver, and pancreas. It is transported in blood to other organs such as muscle and brain, where it is phosphorylated to phosphocreatine. Interconversion of phosphocreatine and creatine is a unique feature of the metabolic processes of muscle contraction; some of the free creatine in muscle spontaneously converts to creatinine, its anhydride. Between 1% and 2% of muscle creatine is converted to creatinine daily.

Collection Details:

Collection Instructions:

State patient's sex and 24-hour total urine volume on the request form.

Plastic urine container, no preservative.

Instruct the patient to void at 8 AM and discard the specimen. Then collect all the urine, including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Measure and record on the test request form the 24-hour total volume. Mix well. Transfer the urine into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Label the container with the patient's name, date, and time collection started and finished. The specimen should be frozen immediately and maintained frozen until tested.