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Test Code
CPEP
Test Name
C-Peptide
CPT Codes
84681
Expected Turnaround Time
3 - 5 days
Clinical Utility
Evaluate residual beta cell function in patients with diabetes mellitus treated with insulin; investigate possible surreptitious injection of insulin. C-Peptide can be used in assessment of beta-cell activity in insulin-treated diabetes mellitus. Progressive exhaustion of beta-cell reserves, as monitored by C-peptide level, can be used to measure metabolic stability or “brittleness” of diabetes mellitus. In transient diabetes mellitus, the return of C-peptide concentrations to within the normal range provides evidence of remission
Specimen and Container Info

Specimen Type: Serum

Preferred Collection Container: Gold Top, Serum Separator

Alternate Collection Container: Red Top, Separator

Minimum Acceptable Volume: 0.8 mL
Processing and Submission Instructions
  1. Centrifuge specimen.
  2. Transfer serum to plastic aliquot tube labeled serum.
  3. Freeze at -20C.

Separator tubes: Contains clot activator and gel for separating serum from cells, but not anticoagulant. Separate serum from cells as soon as the clot has formed (30 minutes). If specimen is centrifuged before clotting is complete, a fibrin clot will form on top of the cell. This may cause the gel barrier to not be intact and could cause improper separation of serum and cells, possibly affecting test results.
Patient Preparation
Fasting
Transport Instructions

Transport to the laboratory frozen.
Stability Requirements

Refrigerated

24 hours

Frozen

7 days
Methodology
Chemiluminescent Immunoassay
Reference Intervals

HNL Lab Medicine Special Chemistry Reference Intervals
Performing Location
Roble Road Core Laboratory
Testing Schedule
Routine, 3 times per week
The American Medical Association (AMA) Current Procedural Terminology (CPT) codes published by HNL Lab Medicine are guidelines and are intended for informational purposes only. CPT coding is the exclusive responsibility of the billing entity. View the Terms.
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