TRANSIENT HYPOCALCEMIA AFTER THYROIDECTOMY

The causes of transient hypocalcemia after thyroid surgery are not ful ly understood. In 95 consecutive patients undergoing total thyroidecto my (n = 30), subtotal thyroidectomy (n = 14), or hemithyroidectomy (n = 5 1), we serially measured total calcium, parathyroid hormone (PTH), and proteins before surgery and 6, 24, 48, 72, and 96 hours after sur gery, and we calculated the corresponding ionized calcium levels. In t he whole population, there was a statistically significant decrease of PTH, total calcium, and proteins at nearly every time of blood withdr awal, when compared with the preoperative levels. The PTH decreased ea rlier and total calcium levels were significantly lower after total th yroidectomy than after hemithyroidectomy (at 48, 72, and 96 hours). Te n patients had on 2 occasions serum calcium levels below or equal to 2 mmol/L and were defined as having severe hypocalcemia. Severe hypocal cemia was found in 8 patients after total thyroidectomy, compared with 2 after hemithyroidectomy (p < .05), and was present in 3 of the 5 pa tients with thyroid carcinoma, compared with 7 of the 90 patients with nonmalignant thyroid diseases (p < .01). Despite careful preservation of the parathyroid glands and their blood supply, thyroidectomy was o ften followed by transient hypocalcemia, the determinants of which are hypoparathyroidism and hemodilution. No patients had persistent sympt oms of hypocalcemia from 2 to 3 months after surgery.