Risk Factors that Predict Levothyroxine Medication after Thyroid Lobectomy

The risk of needing lifelong thyroid hormone supplementation is an important factor affecting treatment decisions for both patients and clinicians ahead thyroid lobectomy. The purposes of this study were to assess the predictive factors of levothyroxine medication after thyroid lobectomy.

We retrospectively reviewed 252 patients who had undergone lobectomy for benign thyroid nodules between April 2009 and April 2017. We conducted two independent analyses: patients who started taking levothyroxine after surgery were compared with those who did not, and patients who did not need levothyroxine at last follow-up were compared with those who required continued treatment. We investigated the correlations of patient clinicopathological characteristics and levothyroxine medication after lobectomy.

Ninety-eight patients started levothyroxine after surgery. Of these, 34 patients successfully ceased medication and 64 patients continued treatment as of their last follow-up. In multivariate analysis, older age and preoperative TSH ≥2.0mIU/L were associated with levothyroxine initiation after surgery. In terms of continuity of levothyroxine, both older age and TSH ≥ 3.0mIU/L showed a significant correlation with continuous medication. We created a risk-scoring system to predict likelihood of starting and maintaining levothyroxine using the two significant factors in each comparison. A risk score of 3 or more indicated an increased risk of starting levothyroxine (specificity = 81.8%; sensitivity = 48.0%). A risk score of 3 or more indicated increased risk of continuous medication, (specificity = 94.2%; sensitivity = 35.9%).

Greater age and higher preoperative TSH levels correlated with initiation and continuity of levothyroxine medication after lobectomy.