Bone isoenzyme of serum alkaline phosphatase and urinary hydroxyproline excretion in thyrotoxicosis.

Studies were performed in 28 patients with proven active untreated thyrotoxicosis and 20 healthy age and sex matched adult subjects. In all subjects serum levels of thyroxine, calcium, phosphate and total activity of serum alkaline phosphatase and its bone isoenzyme were examined. Total urinary hydroxyproline excretion was measured after hydroxyproline free diet. Significant differences were found in the mean serum alkaline phosphatase and its bone isoenzyme levels and in the excretion of urinary hydroxyproline between a group of patients with thyrotoxicosis and a control group. In this study increased bone isoenzyme of alkaline phosphatase activity above the normal range was found in 24 patients with thyrotoxicosis and increased the excretion of urinary hydroxyproline in all patients with thyrotoxicosis. The relationship between the increased bone alkaline phosphatase and urinary hydroxyproline values indicated and increased bone turnover in the early period of disease.