Lower circulating omentin-1 is independently linked to subclinical hypothyroidism reflecting cardiometabolic risk: an observational case-control and interventional, longitudinal study.

Background: Omentin-1, a newly discovered adipokine, is implicated in the modulation of the adipose phenotype, ameliorating systemic metabolism and exhibiting anti-atherogenic, anti-oxidative, cardioprotective, anti-inflammatory and insulin-sensitizing properties. Our goal was to explore circulating omentin-1 in subclinical hypothyroidism (SH) and determine its correlations with cardiometabolic risk factors.

Methods: In a large case-control and interventional longitudinal study, serum omentin-1, metabolic and lipid parameters, inflammatory biomarkers, classic adipocytokines and cardiovascular risk factors were assessed in 120 consecutive patients with SH and 120 healthy controls matched on age, gender and date of blood draw. Sixteen patients with SH were administered L-T4 and, after six months, circulating omentin-1 and other biomarkers were determined.

Results: SH subjects presented significantly decreased circulating omentin-1 than control individuals (P<0.001). In all study participants, omentin-1 was negatively correlated with TSH, anti-thyroid antibodies, HOMA-IR, C-peptide, lipid and inflammatory biomarkers, adipokines and cardiovascular risk factors, including Framingham score and apolipoprotein B. Omentin-1 was positively associated with adiponectin and HDL-C. Circulating omentin-1 was independently associated with SH occurrence, above and beyond clinical and cardiometabolic factors (P=0.04). TSH was a negative independent predictor of serum omentin-1 levels (P<0.001). L-T4 treatment did not alter considerably the lower omentin-1 levels in treated SH patients (P=0.07).

Conclusions: Omentin-1 may be a useful non-invasive biomarker reflecting cardiometabolic risk as well as a promising therapeutic target. More mechanistic and larger prospective studies shedding light on the pathogenetic role of omentin-1 in SH are required to confirm these findings.