Chapter 7 - Evaluation of hypoglycemia

Abstract

Hypoglycemia is a threat to the acute and chronic functioning of the nervous system. In the short term, the brain is solely dependent on glucose for energy. Robbed of this resource, neurologic function can rapidly deteriorate leading to seizures, coma and even death. Recurrent hypoglycemia can severely damage the developing brain of a child. In our biochemical evolution, four hormones have developed to protect us from hypoglycemia. Epinephrine and glucagon protect us from acute hypoglycemia whereas cortisol and growth hormone protect us from more chronic hypoglycemia. Functionally, there is only one hormone that acts to lower plasma glucose concentrations; that hormone is insulin. With a firm foundation in the physiology of glucose regulation, excess insulin, deficient counter regulatory (a.k.a. – “anti-insulin”) hormones, and various liver diseases and inborn errors are major causes of hypoglycemia. Nevertheless, outside of early childhood, most causes of hypoglycemia are drug or medication induced. This chapter reviews the regulation of plasma glucose concentrations, and examines, in detail, the causes of hypoglycemia and the diagnostic approaches to hypoglycemia. This information will assist the clinician and the laboratorian in improving patient management and outcome.