Risk of Hypothyroidism following Hemithyroidectomy: Systematic Review and Meta-Analysis of Prognostic Studies

• Published in: The journal of clinical endocrinology and metabolism Vol. 97; no. 7; pp. 2243 - 2255
• Main Authors: Verloop, Herman, Louwerens, Marloes, Schoones, Jan W, Kievit, Job, Smit, Johannes W. A, Dekkers, Olaf M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01-07-2012; Copyright by The Endocrine Society
• Subjects: Algorithms; Biological and medical sciences; Endocrinopathies; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Humans; Hypothyroidism - diagnosis; Hypothyroidism - epidemiology; Hypothyroidism - etiology; Incidence; Medical sciences; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Postoperative Complications - diagnosis; Postoperative Complications - epidemiology; Postoperative Complications - etiology; Prognosis; Risk Factors; Thyroid. Thyroid axis (diseases); Thyroidectomy - adverse effects; Thyroidectomy - methods; Thyroidectomy - statistics & numerical data; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Endocrinopathy; Obesity; Statistical analysis; Prognosis; Nutrition; Thyroid diseases; Evidence-based practice; Nutrition disorder; Metabolic diseases; Systematic review; Risk; Hypothyroidism; Evidence-based medicine; Metaanalysis; Risk factor; Endocrinology; Nutritional status; Bibliographic review
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2012-1063

Context:
The reported risk of hypothyroidism after hemithyroidectomy shows considerable heterogeneity in literature.
Objective:
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.
Data Sources:
A systematic literature search was performed using several databases, including PubMed.
Study Selection:
Original articles in which an incidence or prevalence of hypothyroidism after primary hemithyroidectomy could be extracted were included.
Data Extraction:
Study identification and data extraction were performed independently by two reviewers. In case of disagreement, a third reviewer was consulted.
Data Synthesis:
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.
Conclusions:
This meta-analysis showed that approximately one in five patients will develop hypothyroidism after hemithyroidectomy, with clinical hypothyroidism in one of 25 operated patients.