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Peptide fragment analysis of proinsulin (8–9 kDa split products)

Published: August 9, 2026Updated: August 16, 2026

This test measures small peptide fragments produced when insulin is processed in your body. It helps assess how well your pancreas is producing and releasing insulin.

Quick summary

["This test may help diagnose or monitor conditions affecting insulin production."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
50468-8
Short code
C peptide sp8 SerPl-sCnc
Synonyms
C peptide sp8 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 Is Done

Your healthcare provider may order this test if you have symptoms of diabetes, insulin resistance, or other metabolic disorders. It can also be used to evaluate pancreatic function or rule out certain endocrine conditions.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. If you’re on insulin therapy, discuss your medication schedule with your provider to ensure accurate results.

What the Results Mean

Elevated levels of these fragments may indicate inefficient insulin processing, sometimes seen in conditions like diabetes or pancreatic disorders. Lower-than-expected levels could suggest abnormal insulin metabolism or rare genetic disorders.

Common Conditions Linked to This Test

This test is particularly useful for diagnosing or monitoring **proinsulin resistance syndromes**, **maturity-onset diabetes of the young (MODY)**, or **pancreatic endocrine tumors**. It may also help assess insulin secretion defects in inherited metabolic disorders.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

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.

◆Associated findings1

Short name

Proinsulin fragments (Serum/Plasma)

Frequently asked questions

What triggers a request for this test?
A doctor may order this test if you have unexplained symptoms like fatigue, weight changes, or family history of diabetes-related disorders. It’s also used in research or specialized clinics studying insulin metabolism.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on lab processing times. Follow-up with your provider to discuss findings and next steps.
Can fasting affect this test?
Fasting may influence insulin-related measurements, but this test focuses on peptide fragments rather than glucose levels. Always confirm with your provider if fasting is required for your specific test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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