Systematic review and meta-analyses of adipokine levels in hypothyroidism: a role for retinol-binding protein 4.

BACKGROUND

Hypothyroidism (HT) is associated with numerous well-characterized comorbidities and established biomarkers for subclinical atherosclerosis which may lead to an elevated risk of cardiovascular disease; however, the precise molecular mechanism underlying these pathological features remains elusive. Increased levels of adipokines may have adverse effects on multiple atherosclerotic risk factors in HT. Different studies have evaluated the association between HT and adipokines with conflicting results.

METHODS

A systematic review and meta-analyses were conducted to provide an overview of adipokine levels in HT. The last literature search was done in February 2024 for studies analyzing traditional and novel circulating adipokines levels (excluding resistin and irisin) in patients with HT. The standard mean differences and 95% confidence intervals (CI) were calculated using random-effect models except if no heterogeneity was found.

RESULTS

HT was not associated with leptin, adiponectin, omentin-1, visfatin, or apelin levels; however, increased retinol-binding protein 4 (RPB4) levels were found in both overall and subclinical HT (p-values = 0.0002 and 0.004 respectively).

CONCLUSION

While pooled analysis suggested a role for RBP4 in hypothyroid patients, associations do not imply cause-effect relationships, and therefore the potential clinical implications of these findings should await further mechanistic studies.

REGISTRATION

The protocol has been registered in the Prospective Register of Systematic Reviews (PROSPERO) under the identification number CRD42024537717.