Pathology tests database

Sample and container requirements

Plain 24hr Urine + 0.5 mL Serum

Minimum volume required

Special requirements

None

Patient preparation

1st Day: 08.00 hours: Start collection of 24 hour specimen of urine in a plain urine container without preservative (white/label with black type). Information sheets and bottles are available from the laboratory. 2nd Day: 08.00 hours: Finish 24 hour collection and send it to the laboratory together with a blood specimen collected during this period for serum creatinine. Both urine and blood specimens must be accompanied by their separate request forms. Shorter urine collection periods may be adopted eg. 4 hours or 12 hours, but a 24 hour collection provides a more reliable result. In children, three accurately timed collections of 20 - 60 minutes may be made.

Sample viability

Turnaround time

This assay is run throughout the day and night. The in-lab turnaround time is normally less than 24 hours. The test can be ordered as an urgent request.

Reference range

Calculation Creatinine Clearance: (U×V)/(P×T) where U: urine creatinine concentration in μmol/L, V: urine volume in mL, P: serum creatinine in μmol/L and T: time of collection in minutes. Values for urinary and plasma (serum) creatinine must be in the same units. NB. Urine creatinine is usually reported in mmol, and the value should be multiplied by 1000 for use in the equation. Females: 72 – 110 mL/min Males: 94 – 140 mL/min

Clinical guidance

The creatinine clearance test compares the level of creatinine in urine with the creatinine level in the blood. (Creatinine is a breakdown product of creatine, which is an important part of muscle.) The test helps provide information on kidney function.

Notes