MUSCULAR WEAKNESS IN OSTEOMALACIA AND HYPERPARATHYROIDISM

A detailed prospective study has been made of the incidence and clinical and biochemical features of proximal muscular weakness in hyperparathyroidism and osteomalacia. In 41 patients with primary hyperparathyroidism, proximal weakness was found only in 1 patient, with a probable parathyroid carcinoma, whereas in 11 osteomalacic subjects there was weakness in at least 8. Investigations showed that the occurrence of weakness was independent of plasma calcium concentration, and no constant biochemical abnormality was found. This confirms the results of a previous study. Weakness always responded to vitamin D therapy, but pre-treatment plasma vitamin D levels were low or normal. It is suggested that myopathy is due to a disturbance of vitamin D metabolism and the reasons for this are discussed. © 1969.