The Journal of clinical investigation
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Comparative Study Clinical Trial
An evaluation of several biochemical markers for bone formation and resorption in a protocol utilizing cyclical parathyroid hormone and calcitonin therapy for osteoporosis.
Female patients (n = 20) with osteoporosis, aged 66 +/- 5 yr were studied during a 24-h infusion of parathyroid hormone (PTH [1-34]) at a rate of 0.5 IU equivalents/kg.h, and then during a 28-d period of subcutaneous injections, at a dose of 800 IU equivalents per day. Thereafter half the patients received subcutaneous injections of calcitonin, 75 U/d for 42 d, and all patients were followed to the end of a 90-d cycle. Biochemical markers of bone formation (serum alkaline phosphatase, osteocalcin, and the carboxy-terminal extension peptide of pro-collagen 1) and bone resorption (fasting urine calcium, hydroxyproline, and deoxypyridinoline) were compared during treatment by the intravenous and subcutaneous route of PTH administration, and subsequently during calcitonin therapy. ⋯ Subsequent treatment of these patients with calcitonin showed no significant changes in the biochemical markers of bone formation and only a modest attenuation of bone resorption. Thus, PTH infusion may inhibit bone formation, as judged by circulating biochemical markers, whereas daily injections confirm the potent anabolic actions of the hormone. Sequential calcitonin therapy does not appear to act synergistically with PTH in cyclical therapeutic protocols.