Defining the spectrum of immunoglobulin A-dominant/codominant glomerular deposition in diabetic nephropathy

In patients with diabetic nephropathy (DN), the spectrum of immunoglobulin A (IgA)-dominant/codominant glomerular deposition (IgAGD) has not been addressed in the literature. The aim of our study is to detail the clinicopathological and outcome findings in patients with DN and IgAGD. Our database was retrospectively searched over a 10-year period for patients with DN and IgAGD. A total of 132 patients were included in the study, 55 with outcome data. All cases were reviewed by light microscopy, immunofluorescence, and electron microscopy. Mean age was 59 ± 13 years, with a 2:1 male-to-female ratio. Indications for biopsy were often multiple, with proteinuria/nephrotic syndrome and acute renal failure being the most common. All patients showed IgAGD and mesangial deposits by electron microscopy. Seventy-three (55.3%) patients had no proliferative glomerular changes and no clinical history of infection and were most consistent with IgA nephropathy on DN, whereas 19 (14.4%) showed proliferative glomerular changes, had a history of infection, and were most consistent with IgA-dominant infection-associated glomerulonephritis. Forty (30.3%) patients showed a mixture of these findings and did not fit into either category. Patients with a mean of 42 (2-120 range) months of follow-up showed an overall poor prognosis, with 59% of all respondents proceeding to renal replacement therapy or death (RRT/D) over an average of 23 (range, 4-54) months. Progression to RRT/D was most frequent in those most consistent with IgA-dominant infection-associated glomerulonephritis (71%), and by multivariate analysis, only advanced Tervaert morphologic classification (classes III and IV) was associated with progression to RRT/D.