[A case with secondary hyperparathyroidism suggesting the direct suppressive effect of maxacalcitol on osteoblasts]

The direct effect of vitamin D on osteoblasts in secondary hyperparathyroidism(2 degrees HPT) is not necessarily obvious. We found an unusual hemodialyzed patient without any response to oral calcitriol pulse therapy(4 micrograms x 2/week), and who was administered maxacalcitol at a dose of up to 15 micrograms x 3/week for 28 months. Plasma intact parathyroid hormone(PTH) was not suppressed from the initial level of 1,773 pg/ml to 2,100 pg/ml. However, on the contrary, alkaline phosphatase(ALP) was successively suppressed from 2 weeks from the initial level of 1,261 IU/l to 276 IU/l. This result suggests a direct suppressive effect of maxacalcitol on osteoblasts in 2 degrees HPT.