Peptide fragment P4 serum/plasma concentration (e.g., proinsulin or related cleavage products)
This test measures certain small peptide fragments found in your blood, which may relate to insulin production or processing. These fragments can help assess how your body handles insulin or identify potential issues with its production.
["This test may be used to evaluate insulin metabolism or detect conditions affecting peptide processing."]
Key facts at a glance
- LOINC
- 25577-8
- Short code
- C peptide sp4 p chal SerPl-sCnc
- Synonyms
- C peptide sp4 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 This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms or risk factors for conditions like diabetes, insulinoma (a rare tumor affecting insulin), or other metabolic disorders. It could also be part of a broader evaluation for unexplained hypoglycemia (low blood sugar) or other endocrine concerns.
What to Expect Before the Test
No special preparation is typically needed, but you may be asked to fast for a few hours before the blood draw if insulin-related fragments are the focus. Always follow your provider’s instructions. Bring any medications you’re taking to discuss with them.
During the Test Process
A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample will be sent to a lab for analysis.
What the Results Mean
Results are interpreted by your healthcare provider based on your clinical picture, symptoms, and other test results. Abnormal levels may suggest issues with insulin production or metabolism, but they don’t stand alone for diagnosis.
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
Short name
P4 Peptide Level
Frequently asked questions
Is this test covered by insurance?
How long will I need to wait for results?
Can I eat or drink before this test?
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