PTH and Hypocalcemia: Kald and Mollerup have established that excision or incision biopsy of more than 2 parathyroid glands, concomitant parathyroidectomy and thyroid surgery, preoperative serum parathyroid hormone level higher than 25 pmol/l, or history of neck-area surgery are risk factors for development of serious postoperative hypocalcemia (3).