Scientific Reports (Aug 2025)

Serum IgA/C3 ratio as a diagnostic and prognostic biomarker for IgA nephropathy

  • Anitha Swamy,
  • Abin Antony,
  • Sudip Kumar Datta,
  • Kalaivani Mani,
  • Adarsh Barwad,
  • Geetika Singh,
  • Arunkumar Subbiah,
  • Raj Kanwar Yadav,
  • Sandeep Mahajan,
  • Dipankar Bhowmik,
  • Sanjay Kumar Agarwal,
  • Soumita Bagchi

DOI
https://doi.org/10.1038/s41598-025-10578-x
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 8

Abstract

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Abstract IgA nephropathy (IgAN) is a common glomerular disease in adults with a smoldering course and high risk of progression to end-stage kidney disease (ESKD) in South Asians. We investigated serum IgA/C3 ratio as a potential biomarker for IgAN. We measured serum levels of IgA and C3 in 258 patients with IgAN and 90 controls with non-IgAN primary glomerular disease and examined if serum IgA/C3 ratio differentiates IgAN from other glomerular diseases and if it predicts renal survival in IgAN. The primary outcome was lack of renal survival, defined as irreversible decline in eGFR > 50% from baseline or progression to ESKD. Median serum IgA/C3 ratio was higher in IgAN patients compared to controls (2.4, IQR: 1.9-3.0 vs. 1.8, IQR: 1.3–2.5, p 2.0 were 70.5% and 62.2% respectively, for differentiating IgAN from other non-IgAN glomerular diseases. With a median duration of follow-up of 35.0(IQR 16-56.8) months, 26.7% patients reached the primary outcome. Compared to patients with a low IgA/C3 ratio(≤ 2.0), those with a high ratio(> 2.0) were significantly older [median age 34 vs. 29 years, p = 0.003], more likely to have hypertension (70.6% vs. 50.5%, p = 0.001), had lower median eGFR [47.7 mL/min/1.73 m² vs. 77.7 mL/min/1.73 m², p 2.0) was not a significant predictor of primary outcome (HR = 1.32 95% CI: 0.80–2.2, p = 0.278). Serum IgA/C3 ratio is elevated in IgAN compared to other glomerular diseases but has limited diagnostic and prognostic utility in our patients.

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