C-Peptide, 24-Hour Urine
Also known as: Connecting Peptide, Insulin C-Peptide, Proinsulin C-Peptide
Use
Urine C-peptide is measured when a continuous assessment of β-cell function is desired or frequent blood sampling is not practical (eg, in children).1 C-peptide excretion in urine has been used to assess pancreatic function in gestational diabetes and in patients with unstable glycemic control in insulin-dependent diabetes mellitus (IDDM).2,3
Special Instructions
This test may exhibit interference if the sample is collected from individuals consuming high doses of biotin. Patients should be asked about supplementation and advised to halt biotin intake at least 72 hours before sample collection.
Limitations
C-peptide levels can be elevated in renal disease due to decreased clearance. The test may be affected by supplements containing biotin, leading to inaccurate results if proper patient preparation is not followed.
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 1987-7
- 1987-7
- 27944-8
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
10 mL
Minimum Volume
1 mL
Container
Plastic urine container
Collection Instructions
Patient should void at 8 AM, discard it, then collect all urine for the next 24 hours, including the final sample at 8 AM the next morning. Ensure pH is between 4 and 7.
Patient Preparation
Patients should stop taking biotin supplements at least 72 hours prior to sample collection.
Storage Instructions
Freeze
Causes for Rejection
pH 8
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 1 day |
| Refrigerated | 14 days |
| Frozen | 14 days |