6 Cases of Transient Hyperphosphatasemia of Infancy and Early Childhood

ABSTRACT

Sometimes physicians and clinical pathologists find very high levels of alkaline phosphatase (ALP) activity in their patients. This condition is associated with transient, marked increase in serum ALP in healthy infants and children. It has also been described in adults. Clinical and biochemical features of transient hyperphosphatasemia in infancy and early childhood are reviewed in six patients that we have studied. The diagnosis is suggested by findings of increased activity of alkaline phosphatase in plasma, typically more than fivefold the upper reference value for adult, in a child under five years of age, without evidence of liver or bone disease. The condition is confirmed by the presence of a characteristic pattern of alkaline phosphatase isoenzymes and by the normalization of enzyme activity in plasma within approximately six months after the original observation. The etiology of the condition and possible mechanism of the elevated ALP is discussed.