Abstract and Introduction
Objective: Changing insights regarding the extent of surgery for low-risk papillary thyroid cancer (PTC) stir up discussions on the benefits and harms of thyroid lobectomy versus total thyroidectomy. The chance of needing postoperative thyroid hormone supplementation after thyroid lobectomy is still unclear. The purpose of this retrospective two-center study was to identify the incidence and risk factors of postoperative thyroid-stimulating hormone (TSH) elevation (>2.0 μIU/ml) after thyroid lobectomy for low-risk PTC.
Design and Methods: Medical records of 201 consecutive patients with low-risk PTC from two tertiary centers who underwent thyroid lobectomy between 2015 and 2019 were retrospectively reviewed. Postoperative thyroid function tests were measured regularly and patients were prescribed levothyroxine if the TSH level was higher than 2.0 μIU/ml. Multivariable regression models were used to evaluate potential risk factors associated with postoperative TSH elevation after thyroid lobectomy.
Results: At 6 weeks postoperatively, 85% had TSH level of >2 μIU/ml; this increased to 88% by 3–6 months. Receiver operating characteristic analysis identified preoperative TSH cut-off (>1.7 μIU/ml) to predict postoperative TSH elevation. Multivariate analysis revealed that only a high preoperative TSH level (>1.7 μIU/ml) was an independent risk factor for a postoperative TSH level of >2 μIU/ml (odds ratio = 7.71; p < .001).
Conclusion: Nearly 90% of the patients who underwent thyroid lobectomy for low-risk PTC had a postoperative TSH level of >2 μIU/ml, necessitating thyroid hormone supplementation in accordance with current guidelines. This finding highlights that preoperative patient counseling should also focus on raising awareness about postoperative thyroid hormone supplementation for low-risk PTC patients seeking thyroid lobectomy.
In 2015, the American Thyroid Association (ATA) recommended either thyroid lobectomy or total thyroidectomy as an acceptable initial procedure for a unifocal intrathyroidal low-risk papillary thyroid cancer (PTC) of <4 cm diameter in patients with no clinically detectable cervical lymph node metastases. However, controversies and significant differences exist in clinical practice due to limited evidence concerning both benefits and harms of thyroid lobectomy and total thyroidectomy and patient and physician preferences.[2–4]
Many factors are involved when considering thyroid lobectomy versus total thyroidectomy.[5,6] Thyroid hormone supplementation is required after total thyroidectomy. The preservation of about half the thyroid gland and the obviation of the need for permanent thyroid hormone supplementation is conventionally thought to be a major advantage of thyroid lobectomy. A recent survey regarding patient preferences around the extent of surgery in low-risk PTC conducted in the United States showed that the requirement for life-long thyroid hormone supplementation after total thyroidectomy was a significant factor impacting patients' preference for thyroid lobectomy.
Postoperatively, a risk-adapted thyroid-stimulating hormone (TSH) suppression strategy has been proposed for PTC patients. For low-risk PTC patients, TSH suppression is not recommended but the normal to low TSH levels (between 0.5 and 2.0 μIU/ml) should be maintained.[1,8] Emerging literature has noted the presence of hypothyroidism after thyroid lobectomy in a non-negligible number of patients. In a recent systematic review pooling 51 studies published between 1986 and 2019, the overall rate of hypothyroidism after thyroid lobectomy for various etiologies was as high as 30%. These studies mostly included patients with benign thyroid diseases and used higher TSH levels to define hypothyroidism. It is, thus, necessary to investigate the prevalence of postoperative TSH elevation (>2 μIU/ml) after thyroid lobectomy for low-risk PTC patients, necessitating thyroid hormone supplementation under current guidelines.
This two-center study attempted to determine the frequency and risk factors for postoperative TSH elevation (>2 μIU/ml) and requirement of thyroid hormone supplementation after thyroid lobectomy for low-risk PTC patients.
Clin Endocrinol. 2022;96(3):413-418. © 2022 Blackwell Publishing