Recognize the clinical utility of measuring C peptide in assessing the origin of insulin (endogenous versus exogenous) in a patient with hypoglycemia.

Explanation:

Hypoglycemia that is documented needs a thorough evaluation.

Potential causes are- exogenous administration of Insulin or oral hypoglcemic agents, Endogenous secretion of insulin or hepatic failure. In diabetics who get hypoglycemic on their usual doses of meds think of renal failure casing accumulation of the meds. Or think decrease in diet Or increase in exercise. Endogenous excess of insulin is associated with elevated C-Peptide levels too. Since Sulfonylureas are associated with high insulin secretion the two need to be distinguished by checking for Sulfonylureas in urine.

If insulinoma is suspected, a 72 hour fast should be done in hospital. If the patient has blood glucose less than 50 mg% during the test with non-suppressed insulin levels, the diagnosis of insulinoma is confirmed. This may be followed up with a CT scan of the Pancreas to localise the tumor.