Benign Transient Hyperphosphatasemia

Abstract

Alkaline Phosphatase (ALP) is a group of four isoenzymes originating in various tissues such as bone, liver, intestine, kidney, and placenta. Serum levels vary throughout life with levels higher in childhood than in adult, especially during the pubertal bone growth spurt. Hyperphosphatasemia can result from physiologic conditions such as puberty and pregnancy, in pathological conditions of bone and the hepatobiliary tract, and in an idiopathic condition known as benign transient hyperphosphatasemia (BTH). The diagnosis of BTH was first described by Bach et al. [1] and in 1985 Kraut et al. [2]defined the diagnostic criteria for this entity as: age of presentation less than five years; no other evidence for bone or liver disease on physical examination or laboratory findings; elevation in both bone and liver ALP isoenzymes; and a return to normal serum ALP values within four months. BTH is accepted as a harmless self-limiting biochemical disorder without sequelae. The aim of this paper is to report a series of BTH cases and to call attention to this condition and the proposed evaluation guidelines to avoid unnecessary costly testing.