Endocrine Abstracts

JOINT28

Introduction: Sporadic thyrotoxicosis following manipulation of thyroid gland during neck surgeries, in particular parathyroid surgeries, has been infrequently described in medical literature and remains largely underrecognised today. We describe a rare case of palpation thyroiditis following parathyroidectomy.

Case Report: A 57-year-old Chinese female with background of end-stage renal disease (ESRD) complicated by tertiary hyperparathyroidism was electively admitted for total parathyroidectomy. She had no known thyroid disorders and was asymptomatic with no history of neck pain or irradiation. Intra-operatively, both thyroid lobes were mobilised and three parathyroid glands were excised except for the right superior gland which could not be definitively located. After parathyroidectomy, the patient remained asymptomatic but was found to have sinus tachycardia on post-operative day two. A thyroid function test done showed elevated free thyroxine (T4) at 53 pmol/l (8 - 16 pmol/l), elevated free triiodothyronine (T3) at 9.0 pmol/l (3.5 - 6.0 pmol/l) and suppressed thyroid-stimulating hormone (TSH) at 0.22 mIU/l (0.45 - 4.50 mIU/l). This was consistent with thyrotoxicosis, and differential diagnoses included palpation thyroiditis from recent parathyroidectomy and less likely undiagnosed Grave’s disease. Further evaluation was then conducted with antithyroid antibody testing and radioiodine uptake thyroid scan. Decision was made to hold off thioamide initiation while awaiting the above investigations given that the patient was asymptomatic and if the diagnosis was truly thyroiditis, her thyrotoxicosis should improve further without treatment. Her thyroid function was closely monitored in the meantime, and she was started on a beta-adrenergic antagonist as needed for palpitations. Subsequently, her antithyroid antibodies including anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG) and thyrotropin receptor antibodies (TRAb) returned negative. The Tc-99m pertechnetate thyroid scan showed generally reduced tracer uptake of the thyroid gland suggestive of thyroiditis, with no dominant ‘hot’ nodule detected. The patient was diagnosed with palpation thyroiditis from recent parathyroidectomy and managed conservatively. Two weeks later, her thyroid function test normalised with no recurrence of sinus tachycardia.

Discussion: It is important to recognise the entity of palpation thyroiditis post-parathyroidectomy – while majority of patients remain asymptomatic for which conservative management is appropriate, some may develop clinically significant thyrotoxicosis requiring further medical treatment.¹ Counselling patients undergoing bilateral neck exploration about this condition, along with prudent post-operative monitoring of thyroid function tests as clinically warranted, is essential for early detection and timely treatment.

References: 1. Stang MT, Yim JH, Challinor SM, Bahl S, Carty SE. Hyperthyroidism after parathyroid exploration. Surgery. 2005;138(6):1058-1065. doi:10.1016/j. surg.2005.09.011