Analysis of Hypoparathyroidism after Thyroid Surgery

Shin, Woo Young; Kim, Seok Won; Park, Kyoung Sik; Han, Wonshik; Noh, Dong Young; Youn, Yeo Kyu; Oh, Seung Keun; Choe, Kuk Jin

Abstract

PURPOSE
Transient hypocalcemia is frequently observed after thyroid operation for most cases. The symptoms are recovered through calcium administration, but some patients suffer from permanent hypocalcemia.
METHODS
We analyzed the medical records of 723 cases who underwent thyroidectomy from Mar 2001 to Dec 2002. Hypocalcemia is defined as case of decreased ionized calcium, and hypoparathyroidism as case of decreased PTH for more than 1 year or decreased ionized calcium despite of administration of calcium more than 1 year.
RESULTS
Out of 723 cases of operation; 139 cases (19.2%) were presented with hypocalcemia after operation. But patients with hypocalcemic symptoms were only 67 cases (9.3%) and with hypoparathyroidism were 15 cases (2.1%). On the basis of operation range, hypocalcemia and hypoparathyroidism were observed more frequently in case of total thyroidectomy (46.9%) than in the cases of operation less than total thyroidectomy (53.1%). Out of total patients, 285 cases(39.4%) were benign while 438 cases (60.6%) were malignant histologically. Hypocalcemia were observed from 22 benign cases and 117 malignant cases, indicating significant difference between the two groups of patients (P <0.001). 2 benign cases and 13 malignant cases had hypoparathyroidism, also indicating significant difference between two groups of patients (P=0.037). In cases of extrathyroidal extension, more frequent hypocalcemia (P<0.004) and hypoparathyroidism were observed (P=0.048). On lo gistic analysis, total thyroidectomy (P=0.004) and extrathyroidal extension (P=0.048) constituted independent risk factor for immediate hypocalcemia and completion thyroidecotmy (P=0.018) and extrathyroidal extension (P=0.037) for permanent hypoparathyroidism.
CONCLUSION
Postoperative hypocalcemia is affected substantially by the extent of thyroidectomy. Therefore close attention is necessary to check and preserve parathyroid glands in case that extent of surgery is more than total thyroidectomy.