Proinsulin
Use
Proinsulin is synthesized in the pancreatic beta cells as a precursor to insulin. Elevated levels of proinsulin are associated with various conditions, such as benign or malignant β-cell tumors of the pancreas, endocrine pancreatic tumors associated with multiple endocrine neoplasia type 1 (MEN-1), and impaired glucose tolerance. High levels can also be a risk factor for developing non-insulin-dependent diabetes mellitus (NIDDM). Elevated proinsulin levels can be observed in patients with chronic renal failure, cirrhosis, or hyperthyroidism.
Special Instructions
Baseline proinsulin levels should be collected after a 12-hour fast. Specimens should be submitted frozen to maintain integrity. Separate specimens for each test are recommended if multiple tests are requested to avoid delays.
Limitations
Proinsulin concentrations are typically low, making it important to handle specimens properly to avoid degradation. Nonfrozen specimens, nonserum specimens, gross hemolysis, and gross lipemia can cause rejection. The turnaround time may be longer if additional confirmatory or reflex tests are required. Testing schedules can vary which may affect the time to release results.
Methodology
Immunoassay (EIA)
Biomarkers
LOINC Codes
- 27882-0
- 27882-0
Result Turnaround Time
3-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.6 mL
Minimum Volume
0.4 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
Transfer the serum into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Patient Preparation
Baseline proinsulin levels should be collected after a 12-hour fast.
Storage Instructions
Freeze.
Causes for Rejection
Nonfrozen specimen; nonserum specimen; gross hemolysis; gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unstable |
| Refrigerated | Unstable |
| Frozen | 12 days |