Insulin
| Category | Biochemistry >> Endocrinology |
|---|---|
| Test background |
Proinsulin is cleaved to form connecting peptide (C-peptide) and insulin prior to secretion into the portal circulation. Insulin is integral to carbohydrate and fatty acid metabolism with utility in cellular glucose uptake, increased glycogen synthesis, enhanced triglyceride turnover and fatty acid esterification in the adipose tissue. Insulin also mediates reduced gluconeogenesis and lipolysis, increased potassium re-uptake, arterial vasodilation and diminished protein catabolism. |
| Clinical Indications |
Insulin is most frequently measured in hypoglycaemia, where it is a useful aid in the diagnosis of insulinoma, other forms of endogenous hyperinsulinism and factitious (exogenous) insulin administration. |
| Reference range | Fasting: 3-15 mIU/L |
| Sample & container required | SST (gold top) or serum (red top) on ice rush to laboratory |
| Sample volume | 1 mL |
| Sample collection | Collect into tube on ice, centrifuge and freeze serum immediately. |
| Transport storage | Send to lab frozen. |
| Turnaround time | 1 week |
| Notes | Grossly haemolysed samples are unsuitable for this assay. |