A new characteristıc of systemic lupus erythematosus: subclinical vein involvement—an in-depth biochemical and imaging study

Objectives Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disorder often complicated by vascular events, with or without antiphospholipid antibody syndrome (APS). This study aimed to explore subclinical venous involvement in SLE using biochemical and imaging modalities, focusing on vein wall thickness (VWT) and inflammation-related biomarkers. Methods In this cross-sectional study, 68 SLE patients were categorized based on antiphospholipid antibody (APA) status and clinical APS. Results were compared with 22 rheumatoid arthritis (RA) patients and 20 healthy controls. Serum levels of P-selectin, growth differentiation factor 15 (GDF15), and citrullinated histone 3 (CH3) were measured using ELISA. Ultrasonographic assessments evaluated VWT at bilateral jugular veins, femoral veins, portal vein and femoral artery. Correlations and predictors of vascular changes were analyzed statistically. Results VWT was significantly increased in SLE patients compared with both control groups (p< 0.001), regardless of APA and APS status. Serum P-selectin, GDF15, and CH3 levels were elevated in SLE-APS patients. GDF15 levels correlated positively with VWT, and increased portal vein wall thickness was independently associated with thrombosis. Biomarkers showed significant associations with APS, suggesting their role as indicators of prothrombotic states. No significant associations were found between vascular parameters and disease activity score. Conclusion Subclinical venous involvement appears to be a novel vascular feature of SLE, reflected by increased vein wall thickness (VWT) and its association with thrombosis and biomarkers. Increased portal vein thickness may indicate vascular risk. Whether these changes result from inflammation or vascular remodeling remains unclear, but their presence irrespective of disease activity highlights their clinical relevance.