Severe Graves' ophthalmopathy may be a risk factor for the development of postthyroidectomy hypocalcaemia

The aim of this study was to compare the rate of hypocalcaemia after thyroid resection in patients with versus patients without Graves' Ophthalmopathy (GO).

153 patients following thyroid surgery for Grave's disease were studied. Patients were divided into three groups according to the severity of GO at the time of surgery using the NOSPECS classification. Subgroup I comprised of 70 patients without GO, subgroup II comprised of 63 patients with moderate GO and 20 patients with severe GO were assigned to Subgroup III. Association between severe ophthalmopathy and postoperative hypocalcaemia after thyroidectomy was investigated.

12/70 patients complained transient and 3/70 permanent hypocalcemia within subgroup I. 14/63 patients developed transient and 4/63 patients permanent hypocalcaemia within subgroup II. There were 7/20 patients with transient and 5/20 cases with permanent hypocalcaemia in the patient group with severe GO (subgroup III). The incidence of permanent postthyroidectomy hypocalcaemia was significantly higher in the subgroup III with severe GO when compared to the subgroup I without GO (p=0.004).

Although postthyroidectomy hypocalcemia seems to be a multifactorial phenomenon, this study implicates unknown role of severe GO at time of surgery in the development of hypocalcaemia after thyroid surgery for Graves' disease. Therefore, patients with GO should be considered for surgery at high volume centres specialised in thyroid and parathyroid surgery.