APLN and hypothyroidism: Analysis of apelin levels in different TH states revealed that apelin levels were higher in patients with hypothyroidism (4.8 ± 2.5 ng/mL) and hyperthyroidism (3.7 ± 1.9 ng/mL) than in the normal population (3.4 ± 1.4 ng/mL), but the difference was not statistically significant [120].