Creatinine, urine

Clinical background:

Urine creatinine is assessed for 3 main reasons:

1. As an assessment of the excretory function of the kidneys as part of a 24hour creatinine clearance test.
2. As an indicator of how concentrated a urine sample is when analysis of other analytes is required (for example urine protein, urine electrolytes, urine amino acids). This also allows these analytes to be reported and interpreted as a creatinine ratio.
3. To assess sample integrity and to assess the reliability of quantitation of other urine analytes (for example urine drug screens).

Specimen container paediatric:

Plain universal container (random urine sample)

Specimen container adult:

Plain universal container (random urine sample) and plain bottle (24 hour urine collection)

Minimum volume paediatric:

1 mL urine

Minimum volume adult:

1 mL urine

Sample stability:

• 2 days at 15-25°C
• 6 days at 2-8°C
• 6 months at -20°C

Interpretation:

Urine creatinine results are rarely interpreted in isolation, but are used to assist interpretation of other urinary analytes.

Reference ranges:

Adult 24 hour collection reference range:

• Female: 6-13mmol/24hour
• Male: 9-19mmol/24hour

Other info:

Acid rinsed bottle acceptable