Morphologic high-risk factors in IgA nephropathy

Morphologic risk factors for developing end-stage renal failure (ESRD) due to IgA nephropathy may be difficult to identify in populations where the course is benign in the vast majority. Ours is a high-risk population.

Protocols of 67 biopsies from native kidneys of kidney transplant patients with IgA nephropathy were reevaluated with respect to the prevalence of certain structural findings. Time points for onset of symptoms, biopsy procedure, and ESRD were recorded.

Features seen with more than expected frequency were: extracapillary proliferation in 49%, cellular infiltrates in the interstitium in 89%, marked tubular atrophy in 54%, and IgA deposits in the peripheral capillary loops in 71%. With extracapillary proliferation the remaining time to ESRD was 3.5 +/- 3.2 versus 7.0 +/- 4.2 years without (p < 0.0004). With marked tubular atrophy the remaining time was 3.5 +/- 2.7 and 8.2 +/- 4.2 years without (p = 0.0002). Cellular infiltrates in the interstitium also signified shorter progression (p = 0.009). Except for the presence of IgA in the periphery, no finding by immune fluorescence was more frequent than expected or correlated with progression.

Extracapillary proliferation, interstitial cellular infiltrates, marked tubular atrophy, and IgA deposits in the peripheral capillary loops indicate risk of progressive renal failure in IgA nephropathy, but other findings by immune fluorescence do not.