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

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.

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".

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).

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.