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Test Code LAB521 C-Peptide, Plasma or Serum

Additional Codes

45328

Reporting Title

C-Peptide

Methodology

Roche Diagnostics, Electrochemiluminescence Immunoassay

C-peptide originates in pancreatic B cells as a by product of cleavage of proinsulin to insulin. It can be used as an index of insulin secretion or suppression. It is valuable in assessing anti-insulin antibodies, covert self-administration of insulin, or insulinomas.

Performing Laboratory

OhioHealth Laboratory Services-RMH Core Chemistry

Specimen Requirements

Submit only 1 of the following specimens:

 

Preferred:

Serum

Draw blood in a gold-top serum gel tube(s) or a mint green gel tube from a fasting patient. Spin down within 3 hours of draw and send 1 mL of serum or plasma refrigerated if within 24 hours and frozen if greater than 24 hours.

 

Note:  

1. A speckled-top serum gel tube(s) or plain red-top is also acceptable.  

2. If multiple specimens are drawn, indicate time of draw and sequence of specimen (eg, 1 hour) on request form and specimen.

3. Heterophile antibodies may interfere with this assay.

4. Indicate serum on request form.
5. Label specimen appropriately (serum).

 

Alternate:

Plasma

Draw blood in a mint green-top (heparin) gel tube(s) from a fasting patient. Spin down within 3 hours of draw and send 1 mL of heparinized plasma frozen in plastic vial.

Note:  1. If multiple specimens are drawn, indicate time of draw and sequence of specimen (eg, 1 hour) on request form and specimen.

2. Heterophile antibodies may interfere with this assay.

3. Indicate plasma on request form.

4. Label specimen appropriately (plasma).

Specimen Stability Information

Specimen Type Temperature Time
Serum or plasma Refrigerated 24 hours
  Ambient  4 hours
  Frozen  30 days

 

 

Specimen Transport Temperature

Frozen/Refrigerate Yes/Ambient NO

Reference Values

0.9-5.0 ng/mL

Reference values are for fasting patients.

Half-life of C-peptide is approximately 30 minutes. Half-life of insulin is approximately 5 minutes. Therefore, circulating level of C-peptide is about 5 times that of insulin despite being secreted in equimolar amounts. The liver clears insulin and the kidneys clear C-peptide, therefore, hepatic and renal complications will affect the circulating C-peptide/insulin ratio.

Day(s) Test Set Up

Monday through Sunday; Continuously

Test Classification and CPT Coding

84681