ASSOCIATIONS AND DISSOCIATIONS BETWEEN SERUM BONE GLA PROTEIN AND ALKALINE-PHOSPHATASE IN SKELETAL METABOLISM

Serum bone Gla protein (BGP) and alkaline phosphatase (AP) activity we re compared for the assessment of skeletal status in 11 normal pregnan t women, 12 normal women on days 3 and 13 of the menstrual cycle, five postmenopausal women before and after 1 month of treatment with ethin yl estradiol (20 mu g/day), five patients with cancer and hypercalcemi a during treatment with calcitonin, and one patient with Paget disease during treatment with Plicamycin. BGP and AP correlated with each oth er only in the pregnant women. In all other circumstances, there was n o correlation between these two serum osteoblast products. Furthermore , there were conditions in which the two measurements became discordan t. These studies demonstrate that BGP and AP commonly are dissociated when used as measurements of skeletal status. Although both are osteob last products, BGP and AP probably reflect different aspects of osteob last differentiation and function.