["Vitamin resistant" osteomalacia due to a defect in hepatic hydroxylation of vitamin D; reversible secondary-pseudo-hypoparathyroidism due to calcium administration].

The authors report a case of vitamin resistant osteomalacia in an adult due to an apparently acquired absence of hepatic hydroxylation of vitamin D. This case was also of interest as the osteomalacia caused a state of type II pseudo-hypoparathyroidism which proved reversible on calcium drip. Thus a defect of hepatic hydroxylation of vitamin D may be a cause of vitamin resistant osteomalacia in the adult apart from the forms already described related to defect of renal hydroxylation of vitamin D. Hypocalcemia may be responsible for hypoparathyroidism due to the coexistence of a rise of circulating immuno-reactive PTH and an increase in urinary cyclic AMP. Normalisation of the calcemia permitted in this case, restoral of the efficacy of endogenous PTH.