Is Presence of ANCA in Crescentic IgA Nephropathy a Coincidence or Novel Clinical Entity? A Case Series
Received 31 March 2009; accepted 28 September 2009. published online 31 December 2009.
Background
There are few anecdotal reports of circulating antineutrophil cytoplasmic autoantibodies (ANCAs) in patients with immunoglobulin A (IgA) nephropathy.
Study Design
Retrospective case series.
Setting & Participants
We studied 8 patients with crescentic IgA nephropathy associated with ANCAs against myeloperoxidase (n = 5) and proteinase 3 (n = 3) followed up for 2.4 ± 1.7 years. They were compared with 26 patients with IgA nephropathy with > 10% crescentic glomeruli, but negative for ANCAs.
Outcomes
We analyzed clinical and histologic features of patients and their response to treatment.
Measurements
Screening for ANCAs was performed using indirect immunofluorescence, and positive results were verified using enzyme-linked immunosorbent assay.
Results
All patients with crescentic IgA nephropathy and positive for ANCAs, compared with only one-third of ANCA-negative patients, presented with the clinical syndrome of rapid progressive glomerulonephritis. ANCA-positive patients reached a higher peak serum creatinine level within the first 3 months (4.2 ± 2.2 vs 2.5 ± 1.9 mg/dL; estimated glomerular filtration rate, 19.3 ± 10.2 vs 45.9 ± 30.1 mL/min/1.73 m2). ANCA-positive patients with IgA nephropathy had a higher percentage of crescentic glomeruli (54.3% ± 18%) compared with ANCA-negative patients with crescentic IgA nephropathy (34.5% ± 26%). ANCA-positive patients were treated using cyclophosphamide and corticosteroids. Kidney function improved in all these patients: serum creatinine level decreased from the peak of 4.2 ± 2.2 to 1.7 ± 0.7 mg/dL at the end of follow up (estimated glomerular filtration rate, 19.3 ± 10.2 to 44.6 ± 11.1 mL/min/1.73 m2). In contrast, no significant improvement was achieved in ANCA-negative patients.
Conclusion
Patients with IgA nephropathy, crescents, and positive for ANCAs represent a clinical entity with a diverse more exaggerated clinical and histologic picture. However, disease in these patients responded well to aggressive immunosuppressive therapy.
ABSTRACT