Benign transient hyperphosphatasemia in childhood

Abstract

Benign transient hyperphosphatasemia of childhood (BTHC) is a rather unknown condition that is associated with a benign state and a good prognosis. BTHC is defined by a sudden and transitory elevation of serum concentration of alkaline phosphatase in healthy children. The etiology of this disorder remains unclear, however the impaired clearance of the enzyme in the circulation seems to be a possible mechanism. To make the current knowledge about BTHC well known , the most relevant papers published since the first description of this condition, in 1954, were selected in Medline database. The diagnostic criteria of BTHC are: being younger than five years, absence of symptoms or presence of symptoms associated with unrelated diseases, without clinic or biochemical evidence of bone or liver diseases. Alkaline phosphatase elevation ranges from 3 to 50 times the upper normal value for age. The isoenzyme analysis shows an elevation in bone and/or liver fractions. Serum alkaline phosphatase levels return to normal in four months. Elevation in serum levels of alkaline phosphatase has also been found in disorders such as asymptomatic and symptomatic persistent familial hyperphosphatasemia and persistent nonfamilial hyperphosphatasemia. Taking into consideration the BTHC is essential in the distinct diagnosis of serum alkaline phosphatase elevation in children when no reasonable cause is detected, thus avoiding unnecessary and expensive procedures during the diagnostic investigation.