EARLY kidney injury markers identified evidence of subclinical renal involvement in patients with seronegative spondyloarthropathies (SpA) without clinically recognised kidney disease, according to findings from a cross-sectional comparative study. Researchers assessed 125 patients with ankylosing spondylitis, psoriatic arthritis, or non-radiographic axial spondyloarthropathy alongside 53 healthy controls to determine whether biomarker changes could indicate early kidney injury before conventional clinical disease becomes apparent.
The investigators measured serum and urinary concentrations of NGAL, KIM-1, RBP4, FGF23, NAG, and IL-18. Several biomarkers differed significantly between patients with SpA and the control group, suggesting the presence of subclinical tubular injury despite the absence of recognised kidney disease.
KIM-1 concentrations were significantly higher in both serum (p=0.039) and urine (p=0.024) among patients with SpA than controls. Urinary RBP4 concentrations were also increased (p=0.005), whereas serum RBP4 concentrations were lower (p<0.001). Urinary FGF23 concentrations were higher in patients than controls (p<0.001), while serum NAG levels also differed between groups (p=0.018).
Overall urinary NGAL and IL-18 concentrations did not differ significantly between all patients and controls. However, subgroup analyses identified distinct biomarker profiles among patients with psoriatic arthritis. These participants demonstrated lower FGF23 concentrations than patients with non-radiographic axial spondyloarthropathy and controls (p=0.028), lower serum NAG concentrations than controls (p=0.013), and higher urinary IL-18 concentrations than controls (p=0.012).
The researchers also examined whether treatment influenced biomarker profiles. Most early kidney injury markers did not differ significantly between patients receiving first line therapies and those treated with biological disease modifying antirheumatic drugs or targeted synthetic disease modifying antirheumatic drugs. The only significant treatment related difference was lower serum FGF23 concentrations among patients receiving second line therapies (p=0.018).
The findings suggested that patients with SpA may experience subclinical tubular injury before overt kidney disease becomes clinically apparent. The researchers concluded that early kidney injury markers may have a potential role in supporting earlier renal assessment in this patient population.
Reference
Tyczyńska KM et al. Early kidney injury markers in patients with seronegative spondyloarthropathies: a cross-sectional comparative study. Sci Rep. 2026:DOI:10.1038/s41598-026-59791-2.
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