Transient hyperphosphatasemia, a benign condition in early childhood endocrinology

Transient hyperphosphatasemia (TH) of infancy and early childhood is a temporary condition marked by a significant elevation in serum alkaline phosphatase levels, involving both liver and bone isoenzymes. It typically affects infants and children under the age of five. Serum alkaline phosphatase levels in cases of TH are usually elevated to four- to five-times the upper limit of the pediatric reference range and naturally return to normal within four to six months. The condition is estimated to occur in ۲%-۵% of healthy children. Most affected individuals are asymptomatic, with no notable findings in their medical history, physical examination, or laboratory results. In some instances, TH may follow a mild viral illness. Elevated alkaline phosphatase levels in children are generally higher compared to adults due to normal physiological osteoblastic activity, with the maximum levels observed during infancy and puberty. TH is defined by an increase in both bone and liver alkaline phosphatase isoenzymes. Although the exact pathogenesis remains unclear, it is hypothesized that the condition involves reduced clearance of alkaline phosphatase due to increased sialic acid content, possibly triggered or compounded by a temporary surge in alkaline phosphatase production. To diagnose TH, physicians aim to rule out other potential causes like liver disease, bone disorders, and renal osteodystrophy through detailed history, physical examination, and laboratory testing. Additional tests might include measurements of AST, ALT, total bilirubin, direct bilirubin, Gamma-GT, calcium, phosphorus, ۲۵- hydroxyvitamin D, PTH, BUN, and creatinine. If an infant or young child shows no evidence of liver or bone disease, TH should be considered as a benign condition. Ensuring adequate vitamin D and calcium intake based on age recommendations is essential for all children during evaluation. The diagnosis of TH can be confirmed when serum alkaline phosphatase levels return to the normal range within ۱-۲۰ weeks without any medical intervention, which can be verified through serial testing.