The pathogenesis of this disorder, characterized by increased PTH secretion and parathyroid gland hyperplasia, is attributed primarily to the retention of phosphate and the decreased capacity to produce active vitamin D. Low serum 1α,25-dihydroxyvitamin D reduces intestinal calcium transport and bone calcium mobilization, and high serum phosphate further contributes to the hypocalcemia by decreasing the free serum calcium. Here, PTH is linked to Hypocalcemia.