Asymptomatic elevation of serum alkaline phosphatase levels has been reported recently in one family. An autosomal dominant inheritance was suggested by father-son transmission.1 Both liver and bone isoenzyme levels were elevated. We describe another family that had elevations of serum alkaline phosphatase levels without apparent disease. In this family, the heat labile fraction (representing the bone isoenzyme level) was greater than 90% in all affected individuals.
Report of a Case.—An 11-year-old asymptomatic girl was found to have an elevated serum alkaline phoshatase level after the incidental discovery of an increased level in her mother. Extensive investigations failed to reveal a cause for the elevated level in the mother. Results of a physical examination of the daughter were entirely normal. Results of laboratory studies, including complete blood cell count, urinalysis, and serum chemistries, were normal except for a fasting serum alkaline phosphatase level of 664 IU/L (normal, 40 to 110