TERTIARY HYPERPARATHYROIDISM AFTER LONG-TERM PHOSPHATE SUPPLEMENTATION IN ADULT-ONSET HYPOPHOSPHATEMIC OSTEOMALACIA

We report the development of tertiary hyperparathyroidism in a patient with a sporadic form of adult-onset hypophosphataemic osteomalacia wh o had been treated with vitamin D or calcitriol and large doses of pho sphate. This observation suggests that even with concomitant vitamin D or calcitriol therapy, long-term oral phosphate supplementation may l ead to the development of hypercalcaemic hyperparathyroidism. Caution is recommended when relatively large doses of phosphate are used to tr eat hypophosphataemic osteomalacia of diverse causes.