Monday, November 19, 2012

HOW TO IDENTIFY THE CAUSE OF HYPOGLYCEMIA


IDENTIFICATION OF CAUSE OF HYPOGLYCEMIA

PLASMA INSULIN AND C-PEPTIDE

Increase in Insulin and C-peptide in the presence of hypoglycemia indicates islet-cell tumors, autoimmune insulin secretion, and drug-induced (sulphonylureas, repaglinide) causing endogenous hyperinsulinaemia.
Decrease in insulin and C-peptide indicates presence of other secondary conditions like chronic renal failure (as C-peptide is excreted by kidney), liver disease, alcohol induced, anorexia nervosa, etc.
Increase in insulin but decrease in C-peptide indicates administration of exogenous insulin, Insulin anti-receptor antibodies (IR-A).

PLASMA Β-HYDROXYBUTYRATE

Hypoglycemia due to hyerinsulinemia shows low ketone bodies. In hypoglycemia due to other conditions like liver disease, anorexia nervosa, hypopituitarism etc, this ketone body is raised.

PLASMA PROINSULIN

Normally only <20% of insulin is released in circulation. In islet cell tumor, circulating proinsulin is increased.

INSULIN ANTIBODIES

The presence of insulin antibodies, due to pre-exposure to exogenous insulin may give false high plasma insulin concentrations. Since C-peptide does not cross-react with insulin antibodies, its measurement can be used as index of β-cell function. 
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