Factors predicting outcome of hypocalcaemia following total thyroidectomy

Postoperative hypocalcaemia is often observed after total thyroidectomy. In patients requiring calcium replacement therapy after 1 year, hypocalcaemia must be considered permanent. The aim of this study was to assess the incidence of hypocalcaemia following total thyroidectomy and to evaluate the risk factors predicting delayed outcome such as hypoparathyroidism. From January 1998 to September 2001, 310 patients underwent total thyroidectomy in our department. In a total of 37 patients experiencing hypocalcaemia, the authors carried out a comparative study of 34 patients with transient hypocalcaemia (group A) and 3 patients with permanent hypocalcaemia (group B). The incidences of transient and permanent hypocalcaemia were 11.9% and 0.9%, respectively. Central neck lymph-node dissection performed in cases of thyroid carcinoma correlated with permanent hypoparathyroidism. The most significant factors predicting long-term outcome of hypocalcaemia were low serum calcium levels (< 8 mg/dl) and high serum phosphorus levels (> 5 mg/dl) measured on postoperative day 7, despite oral calcium replacement. The indications for lymph-node dissection in the central neck area should be very strictly selected. When delayed serum calcium and phosphorus levels are unfavourable, thorough follow-up of patients is mandatory in order to administer the correct therapy and prevent the consequences of chronic hypocalcaemia.