Renalase concentration was statistically significantly lower in the group with moderate-to-severe OSA (AHI ≥ 15) compared with the group without OSA (AHI < 5) (139.56 ± 175.72 ng/ml vs. 230.97 ± 240.50 ng/ml, p = 0.042). Here, RNLS is linked to obstructive sleep apnea syndrome.