Diagnosing insulinoma, when used in conjunction with proinsulin and C-peptide
Management of diabetes mellitus
Electrochemiluminescence Immunoassay (ECLIA)
Fasting Insulin
Immunoreactive Insulin
Insulin Assay
Insulin Level, Serum
Native Insulin
Serum
Patients on insulin therapy may develop anti-insulin antibodies. These antibodies may interfere in the assay system, causing inaccurate results. In such individuals, measurement of free insulin INSFT / Insulin, Free and Total, Serum should be performed.
Patient Preparation:
1. Patient should be fasting.
2. For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Supplies: Sarstedt 5 mL Aliquot Tube (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Avoid hemolysis
2. Label specimens with corresponding collection times.
3. Centrifuge and aliquot serum into plastic vial within 2 hours of collection.
Additional Information: If multiple specimens are drawn, send separate order for each specimen.
0.75 mL
Gross hemolysis | Reject |
Gross lipemia | OK |
Autopsy specimen | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Frozen (preferred) | 180 days | |
Refrigerated | 7 days |
Diagnosing insulinoma, when used in conjunction with proinsulin and C-peptide
Management of diabetes mellitus
Insulin is a hormone produced by the beta cells of the pancreas.
Type 1 diabetes (insulin-dependent diabetes) is caused by insulin deficiency due to destruction of insulin-producing pancreatic islet (beta) cells. Type 2 diabetes (noninsulin-dependent diabetes) is characterized by resistance to the action of insulin (insulin resistance).
Insulin levels may be increased in patients with pancreatic beta cell
2.6-24.9 mcIU/mL
For SI unit Reference Values, see https://www.mayocliniclabs.com/order-tests/si-unit-conversion.html
During prolonged fasting, when the patient's glucose level is reduced to <40 mg/dL, an elevated insulin level plus elevated levels of proinsulin and C-peptide suggest insulinoma.
Insulin levels generally decline in patients with type 1 diabetes mellitus.
In the early stage of type 2 diabetes, insulin levels are either normal or elevated. In the late stage of type 2 diabetes, insulin levels decline.
In normal individuals, insulin levels parallel blood glucose levels.
To compare insulin and C-peptide concentrations (ie, insulin to C-peptide ratio):
-Convert insulin to pmol/L: insulin concentration in mcIU/mL x 6.945 = insulin concentration in pmol/L.
-Convert C-peptide to pmol/L: C-peptide concentration in ng/mL x 331 = C-peptide concentration in pmol/L.
Human antimouse antibodies (
This assay has 100% cross-reactivity with recombinant human insulin
1. Threatte GA, Henry JB: Carbohydrates. In: Henry JB, ed. Clinical Diagnosis and Management by Laboratory Methods. 19th ed. WB Saunders Company; 1996:194-207
2. Sacks DB: Diabetes mellitus. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics 6th ed. Elsevier; 2018:1160-1200
Insulin from the sample, a biotinylated monoclonal insulin-specific antibody, and a monoclonal insulin-specific antibody labeled with a ruthenium complex form a sandwich complex. After addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission, which is measured by a photomultiplier. Results are determined via a calibration curve that is instrument specifically generated by 2-point calibration and a master curve provided via the cobas link.(Package insert: Elecsys Insulin. Roche Diagnostics; v3.0, 06/2020)
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
83525
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
INS | Insulin, S | 27873-9 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
INS | Insulin, S | 27873-9 |