Hypocalcemia following total thyroidectomy: early factors predicting long-term outcome.

Hypocalcemia following total thyroidectomy (TT) must be considered permanent in patients requiring calcium replacement after one year. The aim of this study was to identify early risk factors predicting long-term outcome of postoperative hypocalcemia. Among 453 patients who underwent TT from January 1998 to May 2003, a cross-sectional study between 44 patients with transient hypocalcemia (9.7%) and 3 patients with permanent hypocalcemia (0.7%) was carried out. Both low serum calcium level (< 8 mg/dl) and high serum phosphorus level (> 4.5 mg/dl), measured on postoperative day 7, were predictive for outcome. Central neck lymph node dissection, performed for thyroid carcinoma, also correlated with outcome. Serum phosphorus level > 4.5 mg/dl on postoperative day 7 resulted the only independent factor predicting permanent hypoparathyroidism. Therefore indication for central dissection would be very strict. When serum phosphorus level is unfavorable a correct replacement therapy is mandatory to prevent the consequences of permanent hypocalcemia.