Predictors of thyroxine replacement following hemithyroidectomy in a south east Asian cohort

Hypothyroidism after hemithyroidectomy: a systematic review and meta-analysis

BACKGROUND

The incidence of hypothyroidism following hemithyroidectomy and risk factors associated with its occurrence are not completely understood. This systematic review investigated the incidence and risk factors for hypothyroidism, thyroxine supplementation following hemithyroidectomy as well as the course of post-operative hypothyroidism, including the time to hypothyroidism and incidence of transient hypothyroidism.

METHODS

Searches were conducted in MEDLINE, EMBASE, Scopus, and Cochrane library for studies reporting the incidence of hypothyroidism or thyroxine supplementation following hemithyroidectomy.

RESULTS

Sixty-six studies were eligible for inclusion: 36 reported risk factors, and 27 reported post-operative course of hypothyroidism. Median follow-up was 25.2 months. The pooled incidence of hypothyroidism was 29% (95% CI, 25-34%; P<0.001). Transient hypothyroidism occurred in 34% of patients (95% CI, 21-47%; P<0.001). The pooled incidence of thyroxine supplementation was 23% (95% CI, 19-27%; P<0.001), overt hypothyroidism 4% (95% CI, 2-6%, P<0.001). Risk factors for development of hypothyroidism included pre-operative thyroid stimulating hormone (TSH) (WMD, 0.87; 95% CI, 0.75-0.98; P<0.001), TSH ≥ 2 mIU/L (RR, 2.87; 95% CI, 2.43-3.40; P<0.001), female sex (RR, 1.19; 95% CI, 1.08-1.32; P=0.007), age (WMD, 2.29; 95% CI, 1.20-3.38; P<0.001), right sided hemithyroidectomy (RR, 1.35; 95% CI, 1.10-1.65, P=0.003), the presence of autoantibodies anti-TPO (RR, 1.92; 95% CI, 1.49-2.48; P<0.001), anti-Tg (RR, 1.53; 95% CI, 1.40-1.88; P<0.001), and Hashimoto's thyroiditis (RR, 2.05; 95% CI, 1.57-2.68; P=0.001).

CONCLUSION

A significant number of patients will develop hypothyroidism or require thyroxine following hemithyroidectomy. An awareness of patient risk factors and postoperative thyroid function course will assist in counselling patients on their risk profile and guiding management.

Posthemithyroidectomy Hypothyroidism: Updated Meta-Analysis of Risk Factors and Rates of Remission

INTRODUCTION

The aim of this study was to determine the incidence and risk factors for hypothyroidism, both clinical and subclinical, following hemithyroidectomy in preoperatively euthyroid patients, as well as hypothyroidism remission and its time of remission.

MATERIALS AND METHODS

A search was performed in Medline (via PubMed), Web of Science, and the Cochrane Library using the keywords "hemithyroidectomy + postoperative + hypothyroidism" and "hemithyroidectomy + hormone supplementation".

RESULTS

Fifty-four studies with a total of 9,999 patients were included. After a mean follow-up interval of 48.2 mo, the pooled hypothyroidism rate was 29%. The subclinical hypothyroidism rate was 79% of patients with hypothyroidism (18 studies). Moreover, a meta-analysis of 12 studies indicated a pooled hypothyroidism remission rate after hemithyroidectomy of 42% (95% CI: 24%-60%). Older patient age (MD = -2.54, 95% CI = -3.99, -1.10, P = 0.0006), female gender (OR = 0.69, 95% CI = 0.58, 0.82, P < 0.0001), higher preoperative thyroid-stimulating hormone levels (MD = -0,81, 95% CI = -0.96, -0.66, P < 0.00001), pathological preoperative anti-thyroid peroxidase antibodies (OR = 0.37, 95% CI = 0.24, 0.57, P < 0.00001) and anti-thyroglobulin antibodies (OR = 0.52, 95% CI = 0.36, 0.75, P = 00,005), and right-sided hemithyroidectomy (OR = 0.54, 95% CI = 0.43, 0.68, P < 0.00001) were associated with postoperative hypothyroidism development. In metaregression analysis, Asia presented a significantly higher hypothyroidism rate after hemithyroidectomy (34.6%, 95% CI = 29.3%-9.9%), compared to Europe (22.9%, 95% CI = 16.2%-29.5%, P = 0.037) and Canada (1.8%, 95% CI = -22.6%-26.2%, P = 0.013).

CONCLUSIONS

Hypothyroidism is a frequent and significant postoperative sequela of hemithyroidectomy, necessitating individualization of treatment strategy based on the underlying disease as well as the estimated risk of hypothyroidism and its risk factors.

Risk factors for hypothyroidism following hemithyroidectomy

OBJECTIVE

Hypothyroidism is the most common complication of hemithyroidectomy for thyroid nodules. This retrospective cohort study investigated the prognostic factors for hypothyroidism following hemithyroidectomy.

METHODS

We included patients who underwent hemithyroidectomy between 2016 and 2017, excluding those with history of preoperative hypothyroidism or malignancy on histopathological examination. The primary endpoint was development of hypothyroidism during follow-up (TSH≥2 above normal).

RESULTS

Twenty-six of the 128 included patients (20%) developed postoperative hypothyroidism. The following independent prognostic factors were found: preoperative TSH level>1.5 mIU/L (OR 2.11; P=0.013), and remaining thyroid volume adjusted for body surface area<4.0mL/m2 (OR 1.77; P=0.015). Twenty-one patients (81%) had first TSH values above the upper limit of normal. Postoperatively, first TSH level correlated significantly with the preoperative value (R=0.5779, P<0.001). Levothyroxine was prescribed to 16% of patients, with a mean dose of 0.92μg/kg/day.

CONCLUSION

Patients with TSH>1.5 mIU/or remaining thyroid volume adjusted for body surface area<4.0mL/m2 should have intensified clinical and biological follow-up in the first year after surgery.

Predictive factors for hypothyroidy after hemithyroidectomy

Background: Hemithyroidectomy is one of the most common procedures performed. It is used to treat patients with benign unilateral nodules. Hemithyroidectomy results in fewer risks of hypothyroidism and the need for thyroid hormone replacement therapy. The present study was designed to identify potential clinicopathologic risk factors associated with the onset of biochemical hypothyroidism. Methods: We conducted a retrospective review of all patients who underwent hemithyroidectomy between 2004 and 2019. Hypothyroidism was defined as a serum thyrotropin level greater than 5 mIU/L. The patients were analyzed for age, sex, preoperative and postoperative thyroid stimulating hormone (TSH), state, side, and volume of the remaining lobe, and histologic diagnosis. Results: Hypothyroidism was diagnosed in 30.8% of 214 patients. This complication appeared in the first year in 83.3% of the cases. A preoperative TSH level greater than 1.32 mIU/l, a remaining volume of the lobe less than 3 ml, and the presence of thyroiditis were associated with a significant increase in the risk of developing hypothyroidism (p<0.01). There were no significant differences in age, sex, state, and side of the remaining lobe. The mean thyroxine dose was 57 ± 26 micrograms. Conclusions: The risk of hypothyroidism after hemithyroidectomy should be assessed prior to surgery. Close monitoring is recommended in patients at high risk of developing this complication. However, all patients who undergo hemithyroidectomy should be monitored at least for the first year.

Predictive factors for hypothyroidy after hemithyroidectomy

Background: Hemithyroidectomy is one of the most common procedures performed. It is used to treat patients with benign unilateral nodules. Hemithyroidectomy results in fewer risks of hypothyroidism and the need for thyroid hormone replacement therapy. The present study was designed to identify potential clinicopathologic risk factors associated with the onset of biochemical hypothyroidism. Methods: We conducted a retrospective review of all patients who underwent hemithyroidectomy between 2004 and 2019. Hypothyroidism was defined as a serum thyrotropin level greater than 5 mIU/L. The patients were analyzed for age, sex, preoperative and postoperative thyroid stimulating hormone (TSH), state, side, and volume of the remaining lobe, and histologic diagnosis. Results: Hypothyroidism was diagnosed in 30.8% of 214 patients. This complication appeared in the first year in 83.3% of the cases. A preoperative TSH level greater than 1.32 mIU/l, a remaining volume of the lobe less than 3 ml, and the presence of thyroiditis were associated with a significant increase in the risk of developing hypothyroidism (p<0.01). There were no significant differences in age, sex, state, and side of the remaining lobe. The mean thyroxine dose was 57 ± 26 micrograms. Conclusions: The risk of hypothyroidism after hemithyroidectomy should be assessed prior to surgery. Close monitoring is recommended in patients at high risk of developing this complication. However, all patients who undergo hemithyroidectomy should be monitored at least for the first year.

Risk factors for thyroid hormone replacement therapy after hemithyroidectomy and development of a predictive nomogram

PURPOSE

Hemithyroidectomy 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.

METHODS

Data 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.

RESULTS

Of 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.

CONCLUSIONS

Hypothyroidism 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.

Risk of Hypothyroidism in Women After Radiation Therapy for Breast Cancer

PURPOSE

To study the hypothyroidism risk after adjuvant radiation therapy (RT) and the association of different RT targets with hypothyroidism risk.

METHODS

We studied 4073 women treated with adjuvant RT for breast cancer from 2007 to 2016. The primary endpoint was hypothyroidism development after RT. Patients were divided and analyzed into 3 groups: whole breast (WB)-alone (n = 2468), regional node irradiation (RNI)-Lv.4 (n = 215; cranial border at the subclavian artery, according to the European Society for Radiotherapy and Oncology consensus guideline), and RNI-supraclavicular lymph node (SCL) (n = 1390; cranial border at the cricoid cartilage). In general, RNI-Lv.4 was used in the patients with high-risk pN0 and pN1 breast cancer. In auxiliary analysis, the mean thyroid dose was estimated in each group (total n = 600, 200 from each group). All the doses were converted to the equivalent dose in 2 Gy fractions (EQD2) with α/β ratios of 3.

RESULTS

The median follow-up duration was 84 months (WB-alone, 84 months; RNI-Lv.4, 44 months; RNI-SCL, 91 months). The 3-year hypothyroidism incidence rate differed significantly between the RNI-SCL and WB-alone groups (2.2% vs 0.8%; Bonferroni corrected P [Pc] < .001) but not between the RNI-Lv.4 and WB-alone groups (0.9% vs 0.8%; Pc > .05). The Cox model revealed an adjusted hazard ratio of 2.25 (95% CI, 1.49-3.38) for RNI-SCL vs WB-alone, 1.69 (95% CI, 1.12-2.56) for adjuvant systemic therapies, and 2.07 (95% CI, 1.07-3.99) for age <60 years. In the subgroup analysis, the hypothyroidism risk became more prominent in patients aged <60 years. The mean exposure doses to the thyroid were 0.23 versus 1.93 versus 7.89 Gy (EQD2) for the WB-alone versus RNI-Lv.4 versus RNI-SCL groups (P < .001). No statistically different locoregional recurrence rates were seen between groups (5-year rate: <3%).

CONCLUSIONS

The risk of hypothyroidism increases after RNI-SCL for breast cancer but not after RNI-Lv 4. These data support routine contouring of the thyroid in the RNI setting, and future studies are required to develop optimal dose-volume constraints.

Risk factors for hypothyroidism and thyroid hormone replacement after hemithyroidectomy in papillary thyroid carcinoma

PURPOSE

Thyroid lobectomy is now preferred over total thyroidectomy to preserve thyroid function and reduce complications in patients with low-risk papillary thyroid carcinoma (PTC). One inevitable consequence of thyroidectomy includes hypothyroidism. This study aimed to evaluate the risk factors for hypothyroidism and thyroid hormone replacement after hemithyroidectomy in patients with PTC.

METHODS

We retrospectively studied 353 patients with PTC who underwent hemithyroidectomy with or without central neck dissection from January 2012 to January 2019. We excluded patients who had hypo- or hyperthyroidism preoperatively and those who underwent total or subtotal thyroidectomy. We analyzed various risk factors related to postoperative hypothyroidism and thyroid hormone supplementation.

RESULTS

Of the patients, 54.7% showed hypothyroidism after hemithyroidectomy (n=193 with n=157, subclinical hypothyroidism; n=36, overt hypothyroidism). Ninety-one percent of postoperative hypothyroidism cases developed within 7 months postoperatively. Eventually, 43.1% (n=152) of patients received levothyroxine after hemithyroidectomy. Preoperative high thyroid-stimulating hormone (TSH) level and low free thyroxine (fT4) level were significantly associated with postoperative hypothyroidism and the need for thyroid hormone supplementation postoperatively.

CONCLUSION

Preoperative TSH and fT4 levels are predictive risk factors of hypothyroidism and need for supplementation of levothyroxine after hemithyroidectomy in patients with PTC. Finally, approximately 43% of patients need levothyroxine supplementation after hemithyroidectomy, and individual preoperative counseling is necessary for these patients.

Prevalence of and risk factors for hypothyroidism after hemithyroidectomy: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis evaluated the prevalence of and risk factors for hypothyroidism following hemithyroidectomy as new evidence obtained in recent years warranted an update of previous meta-analyses.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched through November 1, 2019, for articles examining the hypothyroidism prevalence and risk factors after lobectomy. The prevalence rate, risk ratio (RR), weighted mean difference (WMD) and standardized mean difference (SMD) were assessed by conducting a meta-analysis of proportions, binary variables, and continuous variables, respectively, using random-effects models.

RESULTS

Fifty-one studies showed a pooled risk of 29.9% (95% confidence interval (CI), 24.6-35.2%) for hypothyroidism following hemithyroidectomy. Risk factors for the development of postoperative hypothyroidism included the female sex (RR, 1.169; 95% CI, 1.040-1.314; P = 0.009), a higher preoperative thyrotropin (TSH) level (RR, 2.955; 95% CI, 2.399-3.640; P = 0.000), a lower preoperative FT4 level (SMD, -0.818; 95% CI, -1.623--0.013; P = 0.047), concomitant lymphocyte infiltration (RR, 1.558; 95% CI, 1.203-2.018; P = 0.001), Hashimoto's thyroiditis (HT) (RR, 1.480; 95% CI, 1.192-1.838; P = 0.000), a lighter weight of the remaining gland (WMD, -2.740; 95% CI, -3.708--1.772; P = 0.000), and a right side lobectomy (RR, 1.404; 95% CI, 1.075-1.835; P = 0.013).

CONCLUSIONS

Hypothyroidism is a significant complication after lobectomy, and appropriate and personalized surgical strategies should be designed after a careful preoperative assessment based on the estimated risk of hypothyroidism and risk factors.

The Recovery of Thyroid Function in Low-Risk Papillary Thyroid Cancer After Lobectomy: A 3-Year Follow-Up Study

PURPOSE

Management strategies after lobectomy for low-risk papillary thyroid carcinoma (PTC) are controversial. This study aimed to identify the proportion of patients among low-risk PTC patients who do not require hormone replacement therapy and to evaluate the risk factors for postoperative hypothyroidism after lobectomy.

PATIENTS AND METHODS

The records of 190 PTC patients who underwent thyroid lobectomy from January 2017 to December 2018 were retrospectively reviewed. Clinicopathological characteristics and follow-up data were collected. Univariate and multivariate analyses were performed to identify the risk factors associated with postoperative hypothyroidism and the recovery of thyroid function.

RESULTS

In summary, 74.21% of patients (141/190) had normal thyroid function without levothyroxine supplementation, while 40.53% (77/190) developed temporary or permanent hypothyroidism. Multivariate analysis indicated that higher preoperative thyroid-stimulating hormone (TSH) levels (>2.62 mIU/L), Hashimoto's thyroiditis (HT), and right lobectomy were associated with hypothyroidism (all P<0.05). The Area Under Curve (AUC) by logistic analysis was 0.829. Twenty-eight (28/77, 36.4%) patients recovered to the euthyroid state in the first year after surgery, and this recovery was significantly associated with preoperative TSH level. Forty-nine (49/77, 63.6%) patients developed persistent hypothyroidism. The thyroid function of most patients (11/28, 39.3%) recovered in the third month after surgery.

CONCLUSION

Patients with a lower level of preoperative TSH, with left lobectomy and without Hashimoto's thyroiditis had a higher chance of normal thyroid function within the first year after lobectomy. The recovery of thyroid function was associated with the level of preoperative TSH.

Usefulness of 1-year of thyroid stimulating hormone suppression on additional levothyroxine in patients who underwent hemithyroidectomy with papillary thyroid microcarcinoma

Background

The purpose of this study was to identify usefulness of 1-year of thyroid stimulating hormone (TSH) suppression, on additional levothyroxine in patients who underwent hemithyroidectomy with papillary thyroid microcarcinoma (PTMC).

Methods

Two-hundred consecutive patients who had received hemithyroidectomy February 2011 to March 2013, were enrolled, retrospectively. Group 1, only, was taking levothyroxine for a year, postoperatively. We evaluated postoperative hypothyroidism through serum TSH level, measured periodically.

Results

Postoperative TSH >10 was significantly different, at 13% and 25%, between two groups (P=0.036). Twenty patients in group 1, and 32 patients in group 2, received additional levothyroxine. Multivariate analysis showed that 1-year suppression, clinical thyroiditis, and preoperative TSH >2, were significantly associated with additional levothyroxine (OR 2.17, P=0.025 and OR 2.00, P=0.046 and OR 2.64, P=0.006). Too, 1-year TSH suppression, preoperative TSH >2, were also significantly associated with postoperative TSH >10 (OR 2.55, P=0.022 and OR 2.22, P=0.048).

Conclusions

We suggest 1-year TSH suppression after hemithyroidectomy, for PTMC in patients with preoperative TSH >2 mU/L and clinical thyroiditis, to reduce additional levothyroxine.

Levothyroxine Supplementation Following Hemithyroidectomy: Incidence, Risk Factors, and Characteristics

BACKGROUND

The goal of the present study was to determine the actual incidence, predictive risk factors, and clinical characteristics of levothyroxine supplementation (LT4S) used for the management of hypothyroidism after hemithyroidectomy.

METHODS

From 2008 to 2015, we included 535 patients who underwent hemithyroidectomy. LT4S was initiated based on three major criteria: the development of overt hypothyroidism, subclinical hypothyroidism with thyroid-stimulating hormone (TSH) levels > 10 mIU/L, or subclinical hypothyroidism with TSH levels of 4.5-10 mIU/L with associated signs/symptoms.

RESULTS

During the 69-month follow-up period, 321 patients (60%) developed overall hypothyroidism following hemithyroidectomy, and 141 ultimately required LT4S, with an overall LT4S incidence of 26.4%. The most common cause of LT4S initiation was subclinical hypothyroidism with TSH levels > 10 mIU/L. In 141 patients with LT4S, the mean maintenance dose of levothyroxine was 1.34 μg/kg, and only 6 patients (4.3%) discontinued LT4S during the follow-up. The 1-, 3-, 5-, and 7-year LT4S-free survival rates of 535 patients were 88.6%, 80.2%, 73.8%, and 69.1%, respectively. Preoperative TSH levels > 2.12 mIU/L and coexistence of Hashimoto's thyroiditis were significantly associated with LT4S following hemithyroidectomy. The risk of LT4S increased by 1.401 times, as preoperative TSH levels increased by 1 mIU/L.

DISCUSSION

A quarter of patients required LT4S after hemithyroidectomy for the management of hypothyroidism, with a mean maintenance levothyroxine dose of 1.34 μg/kg. The preoperative TSH level and coexistence of Hashimoto's thyroiditis were significant predictive factors of LT4S following hemithyroidectomy.