Two brothers, twenty-four and twenty-nine years old, came to us with osteomalacia, low serum calcium, and increased serum alkaline phosphatase. Serum phosphate and phosphate excretion index were normal on repeated determinations. Inquiry and blood studies disclosed no evidence of osseous disease in relatives.
These patients are felt to represent the syndrome of pseudo-vitamin-D-deficiency rickets, a hereditary disorder described by Prader, Illig, and Heierli. It has been proposed that this disease represents an abnormality of vitamin-D metabolism. Studies of calcium and phosphate balance and infusion of calcium and of parathyroid extract support this abnormality, together with a concomitant resistance to parathyroid hormone-mediated renal phosphate excretion.