Source and significance of serum alkaline phosphatases in diseases of the locomotor system.

A group of 292 patients with diseases of the locomotor system was examined. Elevated activity of the liver isoenzyme of serum alkaline phosphatase was found in rheumatoid arthritis. Evaluation of the alkaline phosphatase isoenzyme in these states is especially important for studying nonspecific irritation of the liver tissue as a result of long-term therapy. Significantly elevated bone isoenzyme activity was found in Paget's disease, ankylosing spondylitis and osteoporomalacia, gout, the hyperuricaemic syndrome and some osteoarthroses. In these states, study of the alkaline phosphatase isoenzymes is of particular significance in evaluation of the development of metabolic bone changes. An association between elevated bone and intestinal isoenzyme activity was found. The diagnostic value of the determination of serum alkaline phosphatase is multiplied if the isoenzymes are also evaluated.