THERE has been increasing interest in disaccharidase deficiencies since the first report of lactose intolerance by Durand1 in 1958. According to recent reviews,2,3 the most common disaccharidase deficiencies are those of sucrase, isomaltase, and lactase. The last is of special interest in pediatrics since lactose is the initial disaccharide encountered by the neonate. Manifestations of lactose intolerance are largely gastrointestinal, and are due to inadequate hydrolysis of the disaccharide. Before lactose is absorbed and utilized, it must be hydrolyzed to glucose and galactose by the enzyme lactase (β-galactosidase) in the epithelial cells of the small intestine.4 Intolerance to lactose may result from a primary enzyme deficiency or from conditions which alter, either anatomically or functionally, the intestinal epithelial cells (secondary intolerance).5,6
The term lactose intolerance is used to describe the development of symptoms after ingestion of lactose. It is, therefore, a clinically observed reaction. Lactase
Caplinger KJ, Boellner SW. Primary Acquired Lactase Deficiency With Acquired Hypogammaglobulinemia: Report of a Case and Review of the Literature. Am J Dis Child. 1968;115(3):377–387. doi:10.1001/archpedi.1968.02100010379015
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