Laboratory Evaluation of Hypoglycemia

Abstract

The evaluation of pediatric hypoglycemia begins with obtaining a meticulous history and physical exam, and once hypoglycemia has been confirmed, the laboratory evaluation has a critical role in identifying the underlying cause. In children, persistent hypoglycemia is more likely to represent congenital or genetic disorders such as inborn errors of metabolism, abnormalities in insulin secretion, or endocrine deficiencies of cortisol and/or growth hormone. In a recent chart review of children who presented to the emergency room with hypoglycemia without an associated known etiology who had undergone diagnostic evaluation, almost 11% were found to have an underlying high-risk disorder (White K, Truong L, Aaron K, Mushtaq N, Thornton PS. The incidence and etiology of previously undiagnosed hypoglycemic disorders in the emergency department. Pediatr Emerg Care. 2018. https://doi.org/10.1097/PEC.0000000000001634. [Publish Ahead of Print]). The diagnostic blood tests, commonly referred to as the “critical sample,” are pivotal not only for the differential diagnosis of these conditions but also to exclude life-threatening conditions such as fatty acid oxidation defects, hyperinsulinism, and adrenal insufficiency and to provide prompt and appropriate care. In young infants, early recognition and evaluation of recurrent hypoglycemia is imperative to prevent the unwanted neurocognitive sequala that can occur in the setting of hypoglycemia due to congenital hyperinsulinism (Steinkrauss L, Lipman TH, Hendell CD, Gerdes M, Thornton PS, Stanley CA. Effects of hypoglycemia on developmental outcome in children with congenital hyperinsulinism. J Pediatr Nurs. 2005;20(2):109–18; Meissner T, Wendel U, Burgard P, Schaetzle S, Mayatepek E. Long-term follow-up of 114 patients with congenital hyperinsulinism. Eur J Endocrinol. 2003;149(1):43–51). In certain cases, properly planned diagnostic fasts, conducted in a hospital setting, are required for further evaluation. This chapter focuses on the laboratory diagnostic evaluation of hypoglycemia and on the interpretation of the critical sample.