HYPOCALCEMIA FOLLOWING THYROID-SURGERY - INCIDENCE AND PREDICTION OF OUTCOME

Postoperative hypocalcemia is a common and most often transient event after extensive thyroid surgery. It may reveal iatrogenic injury to th e parathyroid glands and permanent hypoparathyroidism. We prospectivel y evaluated the incidence of hypocalcemia and permanent hypoparathyroi dism following total or subtotal thyroidectomy in 1071 consecutive pat ients operated during 1990-1991. We then determined in a cross-section al study which early clinical and biochemical characteristics of patie nts experiencing postoperative hypocalcemia correlated with the long-t erm outcome. Postoperative calcemia under 2 mmol/L, was observed in 58 patients (5.4%). In 40 patients hypocalcemia was considered severe (c onfirmed for more than 2 days, symptomatic or both). At 1 year after s urgery Are patients (0.5%) had persistent hypocalcemia. We found that patients carried a high risk for permanent hypoparathyroidism if fewer than three parathyroid glands were preserved in situ during surgery o r the early serum parathyroid hormone level was less than or equal to 12 pg/ml, the delayed serum calcium levels less than or equal to 8 mg/ dl, or the delayed serum phosphorus level greater than or equal to 4 m g/dl under oral calcium therapy. When one or more of these criteria ar e present, long-term follow-up should be enforced to check for chronic hypocalcemia and to avoid its severe complications by approximate sup plement therapy.