Normal ranges and diagnostic value of serum 5'nucleotidase and alkaline phosphatase activities in infancy.

Determinations of serum alkaline phosphatase (APase) and 5′nucleotidase (5Nase) activities have been carried out in 159 children investigated for possible disease of liver or bones, and in 147 children in whom these possibilities never arose. The latter group, which served as a control population, showed 5Nase levels very much lower than those encountered in a normal adult population. APase values in this group rose after birth, fell after the first year, and remained stable until puberty when the range increased slightly. APase was raised in 73% of children with hepatobiliary disease, 65% of children with bone disease, and 28% of children in whom there was no evidence of disease of either type. The corresponding figures for 5Nase activity were 87%, 6%, and 3%, and the degree of increase encountered in hepatobiliary disease was proportionately higher than the increase of APase seen in the same subjects. It is concluded that 5Nase is superior to APase in the diagnosis of hepatobiliary disease in infancy.