CALCIUM AND PHOSPHORUS METABOLISM IN OSTEOMALACIA X. FURTHER STUDIES ON VITAMIN D ACTION: EARLY SIGNS OF DEPLETION AND EFFECT OF MINIMAL DOSES

Abstract

On 3 patients with osteomalacia and one normal infant born of an osteomalacic mother, a study was made of the anti-rachitic potency of the vit. D-deficient diets in common use in investigation of Ca and P metabolism in osteomalacia, of the effect of a minimal dose of vit. D., and of the changes of Ca and P metabolism following the withdrawal of vit. D. The metabolic changes observed were interpreted as evidence of vit. D. depletion. When put on the exptl. diets, whatever beneficial effect they derived from the previous regimen disappeared in the course of time, giving place to the metabolic changes mentioned. These biochemical alterations are regarded as early signs of vit. D depletion and are helpful in providing material for reconstructing the metabolic processes that underlie the development of rickets and osteomalacia. Expts. with very small doses of vit. D in the form of Vigantol (Bayer), or the addition of eggs to the basal diet, demonstrated the efficacy of such minimal doses of vit. D, and confirmed the supposition that the favorable metabolic behavior observed at the beginning of the expts. in all the cases was due to previous vit. D. store which was given up very slowly.