The clinical significance of serum alkaline phosphatase isoenzymes in locomotor diseases.

AP isoenzymes were estimated in 292 patients with locomotor diseases and in 124 healthy controls. The diagnostic usefulness of AP determination is increased by estimation of isoenzymes. Investigations were made to study the biological profile of organ specific AP activities: 1. Rheumatoid arthritis and Reiter's syndrome - the total AP and L-AP activities were increased. 2. Ankylosing spondylitis treated by physiotherapy - the total AP, B-AP and I-AP activities were increased. After drug therapy an increase occurred also in L-AP activity while I-AP activity showed no significant change. 3. Progressive OA of hip and knee showed increased levels of total AP and B-AP activities. 4. Degenerative diseases of the spine, chiefly cases of discopathy, showed significantly reduced levels of AP and B-AP activities. 5. In osteoporosis there was an increase in total AP, L-AP, B-AP and I-AP activities. 6. In the active generalised form of Paget's disease, increased levels were found of total AP, B-AP, I-AP and L-AP activities. 7. In neoplastic diseases the isoenzymes can help to reveal metastatic dissemination and thus aid preoperative evaluation. 8. In gout and hyperuricemic syndromes there was a relative increase of B-AP activity and non-significant fall of L-AP activity. Increased levels of L-AP occured in patients with gallbladder disease, after immunosuppressive therapy or after infectious hepatitis. A fall of L-AP levels was found after Corticotrophin and after intraarticular administration of Kenalog. Increased B-AP activities occurred after total hip replacement, in acute or chronic pyelonephritis and in active osteonecrosis and osteoporosis. Anabolic therapy caused a significant fale of B-AP activity to fall significantly. Reduced B-AP levels were also found after antibiotic therapy. Increased I-AP activity was found in cases of osteoporosis, and in secondary amyloidosis; reduced I-AP activity was seen in mucous colitis. The activity of I-AP is assumed to increase as a result of the changed intestinal calcium and phosphorus regulation occurring in association with the enhanced bone tissue metabolism. From this point of view an order of significance is given for the activity of bone pathology in the separate diagnostic groups of locomotor diseases.