[Changes in serum calcium concentration following eel calcitonin analogue administration as an index of osteoclastic bone resorption in patients with secondary hyperparathyroidism].
It has been suggested that the intensity of hypocalcemic response to administration of calcitonin may reflect the magnitude of osteoclastic activity. To determine whether this hypothesis is correct or not, I performed a calcitonin-loading test in twenty dialysis patients with secondary hyperparathyroidism. The test involved the intravenous injection of 120 MRC units of synthetic eel calcitonin analogue for 3 hours. Serum calcium concentration fell from 9.6 +/- 0.9 mg/dl to 8.7 +/- 0.9 mg/dl following calcitonin administration (p < 0.001). There was a statistically significant correlation between the fall in serum calcium concentration and the baseline intact parathyroid hormone levels (r = 0.661, p < 0.002), as well as the fall in serum calcium concentration and baseline serum alkaline phosphatase activity (r = 0.817, p < 0.001), respectively. From these findings, it was concluded that calcitonin lowers serum calcium concentration in proportional to the activity of osteoclastic bone resorption. To determine whether the effect of calcitonin on calcium concentration related to PTH secretion, same test was performed before and after parathyroidectomy (PTX) in 9 patients with severe secondary hyperparathyroidism required surgery. The fall in serum calcium concentration during calcitonin administration before PTX was significantly greater than that of after PTX (p < 0.05). Thus, it is concluded that calcitonin-loading test is clinically usefull index to estimate osteoclastic activity in patients with secondary hyperparathyroidism.
Kato
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Second Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
D000328:Adult; D000368:Aged; D001862:Bone Resorption; D002116:Calcitonin / Q000031:analogs & derivatives*; D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010010:Osteoclasts
D002116:Calcitonin; D002118:Calcium