Pathogenesis of osteomalacia in secondary hyperparathyroidism after gastrectomy

Described here is a thirty-seven year old man in whom osteomalacia developed five years after subtotal gastrectomy. Gastrointestinal loss of calcium was excessive, endogenous fecal calcium secretion was high, and urinary calcium excretion was low. Circulating parathyroid hormone was present in excess and could be readily decreased by the infusion of calcium or with dihydrotachysterol; with both measures the serum phosphate level returned to normal. It is suggested that a primary defect in calcium absorption led, via a stimulus to the parathyroids, to hyperphosphaturia, hypophosphatemia nd osteomalacia; whereas calcium absorption became almost normal, gastrointestinal hypersecretion of calcium continued.