Creatinine is a waste product formed from muscle metabolism and excreted by the kidneys.

Measuring creatinine in a 24-hour urine sample provides information about kidney function and muscle mass.

Clinical uses include:

Assessing glomerular filtration rate (GFR) when combined with serum creatinine.

Evaluating renal function in suspected kidney disease.

Monitoring patients with chronic kidney disease or muscle disorders.

Supporting diagnosis of abnormal proteinuria (used with protein/albumin ratios).

The test requires collecting all urine passed in 24 hours in a special container.

Analyte: Creatinine concentration in 24-hour urine.

Normal Range: Approximately 500–2000 mg/24 hrs (varies by age, sex, muscle mass, and lab).

High Creatinine Excretion: May indicate high muscle mass, high protein intake, or increased physical activity.

Low Creatinine Excretion: May suggest kidney dysfunction, muscle wasting, or low protein intake.

Clinical Use:

Detects abnormalities in kidney filtration.

Differentiates renal vs non-renal causes of altered creatinine levels.

Provides supportive information for renal and metabolic disorders.