Proinsulin, Serum/Plasma — 12-Hour Fasting, Substance Concentration
Measures fasting proinsulin, a precursor of insulin, in blood to help evaluate pancreatic insulin production and investigate unusual blood sugar patterns.
["A fasting proinsulin test can help clinicians evaluate insulin production, especially when hypoglycemia or an insulin-secreting tumor is suspected."]
Key facts at a glance
- LOINC
- 10451-3
- Short code
- Proinsulin p 12h fast SerPl-sCnc
- Synonyms
- Proinsulin p 12h fast SerPl-sCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- 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
What is this test?
Proinsulin is a precursor that pancreatic cells convert into insulin. This blood test measures proinsulin after a 12-hour fast, providing information about how much insulin-related material is being released into the circulation.
Why might I need this test?
Clinicians may order this test when evaluating recurrent low blood sugar, suspected excess insulin production, or unexplained fasting symptoms. It may also be used in selected cases to assess how the pancreas produces and releases insulin.
How is the test performed?
A blood sample is collected from a vein and analyzed in a laboratory. Results may be interpreted along with your fasting glucose, insulin level, symptoms, medication use, and other tests.
How do I prepare for the test?
Fast for about 12 hours before the blood draw, following the specific instructions provided by your clinician. Water is generally permitted, and any medicines or supplements that could affect insulin and blood sugar should be discussed with the care team before the test.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated fasting proinsulin level may occur with an insulin-secreting tumor or other causes of excess insulin production, particularly when accompanied by low blood sugar. Results can also vary with blood sugar, fasting duration, kidney function, medications, and pancreatic conditions, so the result should be interpreted by a clinician in your overall clinical context.
Short name
Fasting Proinsulin
Frequently asked questions
Is proinsulin the same as insulin?
Why is fasting required for this test?
Does one abnormal proinsulin result diagnose an insulin-secreting tumor?
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 17, 2026. · Read our editorial policy