Evaluation of serum, urine and histopathology findings in anca associated glomerulonephritis

Abstract

Aim: To evaluate the spectrum of serological, urine and histopathology findings in anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN). Background: ANCA-GN is the commonest cause of biopsyproven GN in older Australians and is associated with high morbidity and mortality. Histopathologic classification of ANCA-GN has been shown to aid in prognostication. ANCAGN spectrum is yet to be elucidated in the Australian setting. Methods: Pathology reports of 2048 adult native kidney biopsies with GN were reviewed across Queensland from 2002- 2011, of which 332 were from Royal Brisbane and Women's Hospital. Patient demographics, renal function, haemoglobin, inflammatory markers and urinary abnormalities were compared between ANCA type (myeloperoxidase (MPO) and proteinase 3 (PR3)) and according to histopathologic classification (focal, crescentic, mixed, sclerotic). Results: Average age at biopsy was 61± 15 years, average estimated glomerular filtration rate was 26.8mL/min/1.73m2, 58.8% were males, 88.2% were MPO-positive and the distribution of histopathologic classification was crescentic 35.2%, mixed 34.1%, focal 23.9% and sclerotic 6.8%. MPO-positive patients were significantly older (p<0.05) and had higher urine protein/creatinine ratios (PCR, p<0.03). No significant age or gender differences were seen between ANCA or histology type. Multi-variate regression analysis revealed that those with crescentic classification were significantly more likely to have a presentation C-reactive protein >100mg/L (p<0.02, OR 5.18) and urine PCR >200 g/mol (p<0.05, OR 3.16). Conclusion: This study provides further insight into the epidemiology and pathology of ANCA-GN in the Australian setting. Though renal biopsy remains the gold standard, serum and urine findings may have utility in predicting histopathology and, ultimately, long-term prognosis.<br />