Background: Hypocalcemia is one of the most common acceptable complications in postoperative period after thyroidectomy. Hypomagnesemia has been recognized after parathyroid surgery, and it has not been studied extensively after thyroidectomy. The aim of this study was to estimate magnesium and calcium ion levels in patients undergoing thyroidectomy and to evaluate the association of hypomagnesemia with hypocalcemia after thyroidectomy. A prospective study was conducted in Government Medical College, Calicut, from December 2012 to November 2013.

Materials and methods: all patients had undergone total/near-total/subtotal thyroidectomy. Pre- and postoperative at 24 h and serum calcium and magnesium were measured by automate electrolyte analyzer. Clinical findings of hypocalcemia were recorded. Statistical analysis was done using SPSS software, version 17.0. Unpaired student t-test was used. Pearson Chi-square test or Fisher's exact test was used to compare the percentage for categorical variables.

Results: In our study, 58% of the patients developed hypocalcemia, biochemical and/or symptomatic (S. Ca <8.5). About 34% of patients developed hypomagnesemia, biochemical and/or symptomatic (S. Mg <1.7). About 30% of patients developed both hypocalcemia and hypomagnesemia. About 24% of patients developed symptoms of both hypocalcemia and hypomagnesemia.

Discussion: Thyroidectomy patients were at a risk of transient and permanent hypoparathyroidism because of chances of parathyroid resection during operation. Transient hypocalcemia and hypomagnesemia occur frequently after total thyroidectomy. It is important to monitor both calcium and magnesium levels after total thyroidectomy and to correct deficiencies to facilitate prompt resolution of symptoms.

Conclusion: There is an association of hypomagnesemia with hypocalcemia after thyroidectomy.

Keywords: Hypomagnesemia and hypocalcemia; thyroid gland; thyroidectomy.