[Bone alkaline phosphatase as an activity parameter of acromegaly]

Serum levels of growth hormone (GH: arithmetic mean of three measurements eight hours apart), somatomedin C (SmC), alkaline phosphatase activity and the bone isoenzyme of alkaline phosphatase (as the liver/bone isoenzyme ratio) were measured in 26 patients with acromegaly (11 men and 15 women; mean age 45.5 [24-66] years), 18 in the active and eight in the nonactive phase of the disease. Activity was characterized by a raised (660 [330-1149] ng/ml), inactivity by a normal (186 [40-300] ng/ml) SmC concentration. All 18 patients with active acromegaly had an abnormally low liver/bone isoenzyme ratio (mean of 0.66 [0.01-1.28]). In seven of the eight patients with inactive acromegaly it was within normal limits. Thus measurement of bone alkaline phosphatase, which is significantly cheaper than that of SmC, is suitable for assessing activity.