Peptide fragment analysis (specifically prohormone C-peptide) using high-performance liquid chromatography (HPLC) for plasma
This test measures a small peptide produced along with insulin during blood sugar regulation. It helps assess how well your pancreas is producing insulin naturally.
["C-peptide levels can indicate insulin production and rule out insulin-related conditions."]
Key facts at a glance
- LOINC
- 25571-1
- Short code
- C peptide sp13 p chal SerPl-sCnc
- Synonyms
- C peptide sp13 p chal SerPl-sCnc
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why is this test done?
Your healthcare provider may order this test to evaluate diabetes management, diagnose insulin-producing tumors, or assess pancreatic function when insulin levels alone may not be sufficient. It’s also used in research or specialized settings to measure insulin secretion precisely.
What does the test involve?
A blood sample is drawn, typically from a vein in your arm. The sample is processed to separate and analyze peptide fragments using HPLC, a method that separates and identifies substances based on their movement through a liquid chromatography column.
How is the result interpreted?
Results are compared to a reference range for healthy individuals, though exact values may vary by lab. Elevated levels may suggest overproduction of insulin, while lower levels could indicate reduced pancreatic function or insulin deficiency.
What are the risks or side effects?
The most common side effect is mild bruising or discomfort at the needle insertion site. Rarely, there may be a slight reaction to the blood draw, such as swelling or redness.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: C-peptide levels serve as a reliable marker for endogenous insulin production. Unlike insulin, which can be artificially elevated by medications or injections, C-peptide reflects natural insulin secretion. This test is particularly useful in diagnosing type 1 diabetes (where insulin is often absent) or distinguishing between insulin-dependent and non-dependent conditions. It may also help monitor chronic diabetes management or evaluate pancreatic health in conditions like pancreatitis or cystic fibrosis.
Short name
C-peptide HPLC
Frequently asked questions
What does a high C-peptide level mean?
What does a low C-peptide level mean?
Can this test be done at home?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy