Differential correlation patterns of serum prolactin and total antioxidant status in obstructive sleep apnea

Obstructive sleep apnea (OSA) severity classification relies primarily on the Apnea-Hypopnea Index (AHI), which quantifies event frequency but does not capture event duration or hypoxemic burden. We examined whether serum prolactin and total antioxidant status (TAS) show differential correlation patterns with frequency- versus duration-based polysomnographic parameters, potentially reflecting distinct pathophysiological mechanisms. This cross-sectional study enrolled 55 participants (controls: n = 12, AHI < 5; mild/moderate OSA: n = 22, 5 ≤ AHI < 30; severe OSA: n = 21, AHI ≥ 30) undergoing overnight polysomnography. Fasting serum prolactin and TAS were measured. Spearman correlations examined biomarker associations with AHI (numerically equivalent to the Respiratory Disturbance Index in this cohort), oxygen desaturation index, total apnea-hypopnea duration, longest apnea duration, and lowest oxygen saturation; P -values were adjusted for multiple testing using the Benjamini–Hochberg false discovery rate procedure. Both prolactin (22.7 ± 9.8 vs 14.7 ± 7.2 vs 12.7 ± 7.3 ng/mL, P = .007) and TAS (1.181 ± 0.068 vs 1.122 ± 0.065 vs 1.111 ± 0.057 mmol/L, P = .021) decreased progressively across severity groups. TAS correlated with event frequency (AHI: r = −0.419, q = 0.013) but not with longest apnea duration ( r = −0.223, q = 0.103), while prolactin correlated with both frequency (AHI: r = −0.360, q = 0.017) and duration parameters (longest apnea duration: r = −0.288, q = 0.044). However, when TAS and prolactin correlations were compared directly for each parameter using Steiger Z test for dependent correlations, none of the differences reached statistical significance (all P ≥ .65), indicating that this apparent divergence reflects differing significance thresholds rather than a formally confirmed difference in association strength. A positive correlation between prolactin and lowest oxygen saturation did not retain significance after false discovery rate correction ( q = 0.053) and is considered exploratory. TAS and prolactin show descriptively different correlation patterns with frequency- and duration-based polysomnographic parameters; however, direct statistical comparison did not confirm these differences as significant, and the findings should be regarded as hypothesis-generating rather than confirmed evidence of distinct pathophysiological mechanisms. Larger, independent cohorts are needed to formally test whether these biomarkers diverge in their associations with OSA severity dimensions.