Background: Thyroid function, as assessed by thyroid-stimulating hormone (TSH) levels, was evaluated in patients after thyroid lobectomy. These assessments were analyzed against perioperative measurements to determine if any of these preoperative values were predictive of postoperative hypothyroidism and the need for postoperative levothyroxine treatment.
Methods: In a retrospective study, data from 276 thyroid lobectomy patients were examined. These surgeries occurred over the period from January 2003-December 2012. Age, sex, volume of resected thyroid, thyroiditis, preoperative free T4, TSH, and microsomal antibody levels were analyzed for correlation with postoperative levothyroxine supplementation.
Results: The overall percentage of the patients taking postoperative levothyroxine was 23.6%. The preoperative TSH level showed strong correlation with TSH levels measured 1-mo postoperatively (P < 0.001). Preoperative TSH levels >2.5 mIU/L and positive microsomal antibody showed significant correlation with postoperative levothyroxine supplementation (P < 0.001; relative risk, 8.933, and 3.438, respectively). By stratifying the patients based on preoperative TSH levels and presence of microsomal antibodies, in the low-risk group with TSH <2.5 mIU/L and negative microsomal antibody, 7% of patients received postoperative levothyroxine replacement but in the high-risk group with TSH >2.5 mIU/L and positive microsomal antibody, 77.8% required levothyroxine replacement (P < 0.001).
Conclusions: The most significant preoperative predictors for levothyroxine supplementation are preoperative TSH level and presence of microsomal antibodies. Patients with preoperative TSH <2.5 mIU/L showed a low risk of requiring postoperative levothyroxine supplementation.
Keywords: Hemithyroidectomy; Hypothyroidism; Papillary thyroid carcinoma; Thyroid lobectomy; Thyroid-stimulating hormone.
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