Clinical value of combined serum galectin-9 and urine MCP-1 testing for assessment of systemic lupus erythematosus disease activity and early diagnosis of lupus nephritis

OBJECTIVES: To investigate whether combined measurement of serum galectin-9 and urinary monocyte chemoattractant protein-1 (MCP-1) can serve as non-invasive biomarkers for assessing disease activity in systemic lupus erythematosus (SLE) and for the early identification of lupus nephritis (LN). METHODS: This retrospective study included 148 SLE patients hospitalized between June 2022 and May 2025. Patients were divided into three groups: inactive SLE group (n=48), active SLE without LN group (n=40), and active SLE with LN group (n=60). Serum galectin-9, urinary MCP-1, and routine indices (e.g., complement levels, autoantibodies) were measured at admission. RESULTS: Serum markers increased progressively with disease progression: galectin-9 levels (8.59 ± 0.63 vs. 9.68 ± 1.87 vs. 11.72 ± 2.14 ng/mL) and urinary MCP-1 levels (1.58 ± 0.42 vs. 2.85 ± 0.92 vs. 10.45 ± 3.18 pg/mg creatinine, all P