Bilirubin and albumin-based inflammatory ratios in women with antiphospholipid syndrome

Background and objectives. Recent evidence has demonstrated that mildly elevated bilirubin concentrations are protective against various oxidative stress-mediated diseases, including autoimmune disorders. Based on this, the present study aimed to investigate the association between serum bilirubin levels, albumin-based inflammatory ratios, and the presence of primary antiphospholipid syndrome (APS) in women with a history of spontaneous miscarriages. Materials and methods. This cross-sectional observational study included 72 women aged 21–40 years (median age 27) with a history of spontaneous miscarriages in the first trimester. Based on clinical and laboratory findings, 47 women were diagnosed with APS, and 25 were classified as non-APS. All participants underwent a complete evaluation, including blood count, coagulation tests, glucose and lipid profiles, CRP, vitamin D, and assessments of thyroid, liver, and kidney function. Results. A total bilirubin level below 8 μmol/L was observed in 53% of APS patients, significantly higher than in non-APS women (24%, p = 0.024). Total, direct, and indirect bilirubin concentrations were significantly lower, while inflammatory markers such as fibrinogen, CRP, and CRP/albumin ratio were significantly higher in APS patients (p < 0.05). Logistic regression and ROC analysis confirmed the diagnostic value of these markers. The AUC values for total bilirubin, bilirubin/albumin ratio, fibrinogen, albumin/fibrinogen ratio, CRP, and CRP/albumin ratio demonstrated moderate diagnostic accuracy (AUC = 0.723, 0.793, 0.693, 0.828, 0.761, and 0.699, respectively). Conclusions. Serum bilirubin levels and the bilirubin/albumin ratio were negatively associated with APS in women with a history of spontaneous miscarriage. These findings suggest impaired antioxidant and anti-inflammatory defenses in APS patients. Serum bilirubin combined with albumin-based inflammatory ratios may serve as additional screening tools for APS in this population.