Determinants of anemia in patients with primary glomerulonephritis: a biopsy-based analysis

Anemia is the second most common comorbidity among patients with chronic kidney disease. Renal tubulointerstitial lesions in patients with primary glomerular disease may result in anemia. This study aims to demonstrate the relation between interstitial fibrosis (IF) grades and anemia parameters in patients with primary glomerulonephritis (PGN).

358 biopsy-proven PGN patients were included for this retrospective, cross-sectional study. We recorded the biopsy findings, demographic, clinical, and laboratory parameters of all patients on the biopsy day. The IF/cortical tissue ratio was calculated and classified into three groups; none, mild and moderate-severe IF.

The mean age of the patients was 43.0 ± 13.8 years, and 54.5% of patients were male. Anemia was present in 41.6% of patients. Hemoglobin and hematocrit decreased across rising IF categories (Hb: 13.1 vs 12.6 vs 12.3 g/dL; p = 0.026; post hoc difference driven by no IF vs moderate - severe IF, p = 0.046). However, in multivariable models, lower transferrin saturation, higher CRP, and lower eGFR were independently associated with anemia, whereas IF was not an independent determinant.

In PGN, IF severity correlates with lower hemoglobin, but does not independently predict anemia after accounting for iron status, inflammation, and kidney function. Anemia appears mainly related to iron availability, inflammatory conditions, and eGFR rather than IF.