Risk of Hypothyroidism following Hemithyroidectomy: Systematic Review and Meta-Analysis of Prognostic Studies
The reported risk of hypothyroidism after hemithyroidectomy shows considerable heterogeneity in literature.
The aim of this systematic review and meta-analysis was to determine the overall risk of hypothyroidism, both clinical and subclinical, after hemithyroidectomy. Furthermore, we aimed to identify risk factors for postoperative hypothyroidism.
A systematic literature search was performed using several databases, including PubMed.
Original articles in which an incidence or prevalence of hypothyroidism after primary hemithyroidectomy could be extracted were included.
Study identification and data extraction were performed independently by two reviewers. In case of disagreement, a third reviewer was consulted.
A total of 32 studies were included in this meta-analysis. Meta-analysis was performed using logistic regression with random effect at study level. The overall risk of hypothyroidism after hemithyroidectomy was 22% (95% confidence interval, 19-27). A clear distinction between clinical (supranormal TSH levels and subnormal thyroid hormone levels) and subclinical (supranormal TSH levels and thyroid hormone levels within the normal range) hypothyroidism was provided in four studies. These studies reported on an estimated risk of 12% for subclinical hypothyroidism and 4% for clinical hypothyroidism. Positive anti-thyroid peroxidase status is a relevant preoperative indicator of hypothyroidism after surgery. Effect estimates did not differ substantially between studies with lower risk of bias and studies with higher risk of bias.
This meta-analysis showed that approximately one in five patients will develop hypothyroidism after hemithyroidectomy, with clinical hypothyroidism in one of 25 operated patients.
Figures in this publication
Available from: M. Akkari
- "The rate of post-operative hypothyroidism after hemi thyroidectomy in adults found in literature varies from 10.9%  to 42.6% . In 2012, a meta-analysis of Verloop et al.  reported that 1 in 5 patients would develop hypothyroidism after hemi thyroidectomy. These data are close to our results in children. "
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Diagnostic and therapeutic processing of a thyroid nodule in children and adolescents may require lobectomy-isthmusectomy (LI) or nodule-resection (NR). Very few data in the literature report the long-term evolution of the remaining thyroid lobe in a defined pediatric population. In this study, we aimed to answer the following questions: Does a nodule recurrence occur in the remainder lobe? Is a post-operative thyroxine treatment necessary?
Material and Methods
This retrospective study describes 28 patients under 18 who underwent LI (22 cases) or NR (6 cases) from January 2004 to March 2012. Ten of them were lost to follow up, 18 could be assessed (4 NR (22%) and 14 LI (78%) - mean follow-up 45 ± 31 months). All patients benefited of post-operative thyroid ultrasonography, and regular endocrinologic follow-up. The following data were analysed: emergence of new thyroid nodules, evolution of pre-existing nodules, occurrence of post-operative hypothyroidism and requirement for completion thyroidectomy.
The mean age at the time of surgery was 14.3 ± 1.9 years. Two patients (11%) had pre-existing nodules in the remaining thyroid gland, none of which showed an increase in size after surgery. De novo nodules developed in 5 patients (27.8%). Three patients who underwent LI (21.4%) needed thyroxine treatment for post-operative hypothyroidism. One patient (5.5%) needed completion thyroidectomy.
In this children and adolescents population, after performing LI or NR, remaining thyroid tissue stays free of nodules in 72.2% of the cases. A post-operative thyroxin treatment is necessary in 21.4% of cases after LI.
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Thyroid nodules are exceedingly common, and the cytologic interpretation of fine needle aspiration (FNA) findings has been the reference standard for diagnosing nodules as benign, atypia or a follicular lesion of undetermined significance, suspicious for follicular or Hürthle cell neoplasm, suspicious for malignancy, or malignant. Many patients undergo thyroid lobectomy for indeterminate FNA findings (atypia or a follicular lesion of undetermined significance or suspicious for follicular or Hürthle cell neoplasm), although the risk of malignancy is low. The general data have quoted a 20% risk of hypothyroidism after lobectomy. The purpose of the present study was to determine the risk of hypothyroidism after lobectomy in our diverse population.
The pathology records from a large county hospital were reviewed to identify patients with indeterminate FNA findings. The incidence of hypothyroidism was determined by the need for thyroid hormone replacement therapy. Categorical variables were compared using the chi-square and continuous variables using the Mann-Whitney U test.
A total of 655 FNAs were performed during the study period, and 60 resulted in indeterminate cases. Of these 60 patients, 17 subsequently underwent diagnostic lobectomy. The mean age was 52.8 ± 16.5 years, 88% were women, and 67% were Hispanic and 22% were African American. Only 6% had a final diagnosis of cancer, and eight patients (47%) became hypothyroid postoperatively.
The incidence of hypothyroidism after diagnostic thyroid lobectomy in our patient population was much higher than previously reported. It is necessary to preoperatively counsel patients about this increased risk, in addition to the usual risks of nerve palsy and bleeding, with thyroid lobectomy. As testing of thyroid nodules evolves, the expense of preoperative testing should be weighed against the increased incidence for lifelong thyroid hormone replacement.
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ABSTRACT: The purpose of this study is to evaluate the suitability of lobectomy with isthmectomy (LwI) in treatment of Follicular Thyroid Neoplasms (FTN), considering malignancy incidence and postoperative complications.
192 patients (165 females; 27 males) who underwent LwI for FTN from 01/2005 to 12/2007 were retrospectively evaluated: clinical and pathological features, surgical complications and five year outcome. Inclusion criteria were cytological Bethesda category III and IV or histological follicular adenoma/carcinoma or follicular variant of papillary carcinoma). Metastatic disease or previous thyroidal surgery patients were excluded.
Mean age was 48.68±14.93yrs. Overall malignancy occurred in 88 patients (45.83%) and 80 (41.67%) underwent thyroidectomy completion (TC), mainly by index lesion's malignancy. Forty-one (21.35%) in LwI and 31 (38.75%) in TC specimens had associated malignancy, mainly papillary microcarcinomas. High preoperative Thyroid-Stimulating Hormone (TSH), histological multinodularity and, in cytology category IV, younger age, were significantly associated to malignancy. Permanent recurrent laryngeal nerve lesion occurred in 0.58% in Lwl and 1.52% in TC, and temporary dysphonia occurred in 9.25% and 6.06% (LwI and TC respectively). No LwI patients presented hypoparathyroidism whereas 3.03% in TC had temporary symptoms. In LwI, 36.70% developed hypothyroidism. Higher preoperative TSH was associated with hypothyroidism development.
LwI was inappropriate in 40.10% patients with malignancy who required TC and 23.12% had no functional benefit because post-LwI hypothyroidism. Nodular relapse was reported in at least 23/113 LwI patients (20.35%). We propose total thyroidectomy for patients with FTN preoperative TSH higher than 2.16 mU/L and, in Bethesda category IV, less than 39.5yrs.
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