[Diagnostic procedures in pediatric hypoglycemias].

Depending on its etiology hypoglycemia appears after short or prolonged periods of fasting and shows different metabolite and hormonal patterns. In children it is caused by a disturbed homoeostasis of blood glucose (hormonal disorders, decreased activity of glycogenolysis or gluconeogenesis), by a primarily decreased ketogenic activity, or by a deranged adjustment of ketogenesis and carbohydrate metabolism. For the diagnostic procedure the age at manifestation, periods of fasting as well as signs and symptoms (f.e. hepatomegaly, growth retardation, somnolence) have to be carefully evaluated. Based on the extent of ketonemia the hypoglycemic syndromes can be classified into ketotic and hypoketotic forms. Hyperinsulinism, defects in fatty acid oxydation, glycogen storage disease I and postprandial hypoglycemias belong to the second category. In diagnosing hypoglycemia analysis of metabolite (glucose, lactate, beta-hydroxybutyrate, free fatty acids, carnitine) and hormonal (insulin, cortisol, growth hormone) patterns during hypoglycemic episodes is of outstanding importance. Urine has to be analysed for abnormal organic acids in order to demonstrate disturbed fatty acid oxydation. Rarely, loading tests with intermediates of carbohydrate metabolism are necessary. Suspected enzyme deficiencies have to be demonstrated in appropriate tissues (liver biopsy, erythrocytes, fibroblasts).