Abstract
PurposeHemithyroidectomy is a valid operation to retain functional contralateral thyroid lobe that is indicated for a variety of thyroid diseases. This study aimed at determination of the risk factors for thyroid hormone replacement following hemithyroidectomy and to develop a predictive nomogram.MethodsData of patients treated by hemithyroidectomy for benign thyroid disease between January 2015 and January 2020 were retrospectively analyzed. Baseline characteristics, surgery-related variables, and preoperative and postoperative thyroid function of patients were collected from the case records and compared between patients with postoperative euthyroidism and patients with postoperative hypothyroidism. Postoperative euthyroidism patients without thyroid hormone replacement were compared to those who developed postoperative hypothyroidism with thyroid hormone replacement. The factors associated with thyroid hormone replacement were used to construct a binomial logistic-regression model and visualized as a predictive nomogram to evaluate the risk of thyroid hormone replacement following hemithyroidectomy.ResultsOf the 378 patients (74% female) included in the study, 110 (29.1%) developed postoperative hypothyroidism. Preoperative serum thyroid-stimulating hormone (TSH) > 2.172 μIU/mL was identified as an independent risk factor for postoperative hypothyroidism (odds ratio [OR] = 8.02; 95% confidence interval [CI]: 4.87–13.20; P < 0.001). Of 110 patients with postoperative hypothyroidism, 56 (50.9%) received thyroid hormone replacement. Unilateral thyroid nodule and preoperative serum TSH > 2.172 μIU/mL were independent predictors of postoperative thyroid hormone replacement (P = 0.01, and P < 0.001, respectively). Temporary subclinical hypothyroidism occurred in 12 patients; all 12 reverted to euthyroid state without thyroid hormone replacement. The discriminative effect of the binomial regression model was proved reliable by the Hosmer–Lemeshow goodness-of-fit test (P = 0.503), and predictive ability of the nomogram was satisfactory with a C-index of 0.833.ConclusionsHypothyroidism is common after hemithyroidectomy, and almost half of the patients will need thyroid hormone replacement. Elevated preoperative serum TSH level and unilateral thyroid nodule were independent predictors of thyroid hormone replacement following hemithyroidectomy. The predictive nomogram could be a useful tool for clinical practice.
Highlights
Hemithyroidectomy is performed for a variety of indications, including benign and malignant thyroid disease and pathologically indeterminate nodule [1, 2]
Compared to the euthyroidism group, the hypothyroidism group had significantly lower mean preoperative FT3 and FT4 level, higher mean thyroid-stimulating hormone (TSH), higher proportion of patients with serum TSH > 2.172 μIU/mL, higher proportion of patients positive for thyroid peroxidase antibody (TPOAb), and higher proportion of patients with concurrent Hashimoto thyroiditis
In univariate logistic regression analysis, preoperative serum TSH > 2.172 μIU/mL was significantly associated with likelihood of postoperative hypothyroidism (OR, 7.47; 95% confidence intervals (CIs), 4.43 to 12.62; P < 0.001)
Summary
Hemithyroidectomy is performed for a variety of indications, including benign and malignant thyroid disease and pathologically indeterminate nodule [1, 2]. Endogenous thyroid hormone (TH) secretion from the remained functional contralateral thyroid lobe usually fulfills the physiological need for TH [3]. 11–45% of patients will develop hypothyroidism and require TH replacement [4,5,6]. To avoid the ill effects of hypothyroidism on the body, some surgeons start TH supplementations immediately after surgery. Long-term TH therapy may itself cause adverse effects such as hypocalcemia, myocardial damage. Endocrine and auricular fibrillation [7,8,9]. It is important to precisely identify patients who are at risk for hypothyroidism after hemithyroidectomy, give the TH supplementation therapy
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