Does autoimmune thyroid disease affect parathyroid autotransplantation and survival?

Background: While the increased risk to parathyroid gland preservation has long been recognized during surgery for thyroid cancer, the effect of different benign pathological conditions on parathyroid preservation has not previously been reported. The aim of this study was to examine parathyroid viability in relation to autoimmune thyroid disease. Methods: This is a retrospective cohort study including all patients having an initial total thyroidectomy (TT) performed by this unit during the period 2004-2005. Results: A total of 628 patients underwent TT in the study period. For the Graves' disease cases, 45 (62.5%) required the autotransplantation of one or less parathyroid gland, whereas 27 (37.5%) required two or more glands to be autotransplanted. This was significantly higher than for the benign thyroid disease group in which the respective figures were 242 (77.6%) and 70 (22.4%) (P = 0.01). Of the lymphocytic thyroiditis cases, 61 (65.5%) required the autotransplantation of one or less gland, whereas 32 (34.4%) required the autotransplantation of two or more glands. This was also significantly higher (P = 0.03). Temporary hypocalcaemia was significantly higher when two or more glands were autotransplanted (23 out of 177, 13.2%) than one or less gland autotransplanted (18 out of 451, 4.0%, P < 0.01). However, the overall incidence of permanent hypoparathyroidism was 1.0%, and there was no significant difference between the groups. Conclusion: TT performed for Graves' disease and lymphocytic thyroiditis results in the autotransplantation of more parathyroid glands, leading to a higher incidence of temporary hypocalcaemia post-operatively. Despite this, the incidence of permanent hypoparathyroidism remains low at 1%.