Endocrine-metabolic relationships in patients with leprechaunism.

Leprechaunism is a rare, heritable syndrome, associated with multiple dysmorphic and pathologic features, suggestive of an endocrine dysfunction. Few endocrine and metabolic studies have been obtained because of the rarity of the syndrome, and the small size and early demise of these infants. The authors present here the clinical, anatomic, and endocrine-metabolic studies of three patients, with a view toward careful delineation of the syndrome and further characterization of the metabolic defect.The most striking and consistent metabolic derangements present in all of these patients were fasting hypoglycemia (less than 20 mg/dL), postprandial hyperglycemia (more than 250 mg/dL), marked hyperinsulinemia (more than 2000 μU/mL), and severe insulin resistance (less than a 20 percent decrease in blood sugar with 0.3 to 1.0 U/kg of regular insulin IV). Hyperinsulinemia was observed in response to oral feedings and glucose infusion, and after tolbutamide. Insulin secretion was less marked with amino acid infusions. Normal increments in blood glucose occurred following alanine, galactose, and glycerol. Glucagon caused a rise in glucose 4 hours after a meal, but no response was seen after a 12-hour fast. Pituitary, gonadal, and adrenal hormone levels were normal, and there was a normal response pattern to GnRH and TRH. Hyperinsulinemia would appear to be the biochemical hallmark of this disease. Our previous studies were suggestive of a postreceptor defect in insulin action. The present endocrine-metabolic studies are compatible with this hypothesis. Interaction of supraphysiologic concentrations of plasma insulin with growth factor receptors, this may provide a partial explanation for some of the dysmorphic features seen in the disorder.