I recognise along with the authors that hypocalcaemia is an accepted complication of thyroid surgery, and monitoring for hypocalcaemia in the postoperative period is essential. However, I feel that the rate of hypocalcaemia quoted by Pfleiderer et al. is high, particularly, the temporary hypocalcaemia (43%). I believe that, in clinical practice, the symptomatic hypoparathyroidism rate is of most significance. Pfleiderer et al. quote this as 24%. We performed 79 total thyroidectomies (excluding the completion surgery) over the last 4 years (2004–2008); only five (6%) patients had temporary hypocalcaemia and one (1.2%) patient had permanent hypocalcaemia. The BAETS audit data quote a rate of 30% with temporary hypocalcaemia and 7% with permanent damage necessitating treatment.
The authors have suggested that identifying the parathyroid glands is a risk factor for hypocalcaemia. In their study, hypocalcaemia has been attributed to various causes, including increased diathermy use, especially in toxic goitres. The standard approach to prevent parathyroid injury and subsequent hypocalcaemia during thyroid surgery is to look for, and preserve, the superior parathyroid glands, and staying close to the thyroid gland to avoid and, therefore, preserve the inferior parathyroid glands. Our low rates of hypocalcaemia are, we believe, due to the fact that we routinely identify the parathyroid glands during surgery. We also use the harmonic scalpel in total thyroidectomies, which minimises bleeding and injury to the parathyroid glands. Where the parathyroid glands have been devascularised, parathyroid gland autotransplantation is also used in our unit in an attempt to prevent permanent hypoparathyroidism.