Kidney disease IgA, formally known as IgA nephropathy, is an immunological diagnostic term for chronic glomerulonephritis. It is characterized by the deposition of immune complexes, primarily IgA, in the mesangial areas of the glomeruli. IgA is a type of immunoglobulin, which upon deposition in the kidneys induces inflammatory responses, leading to proliferation of mesangial cells, accumulation of mesangial matrix, and widening of the mesangial area. This can cause damage to the glomerular filtration barrier, manifesting as proteinuria and hematuria. Some patients may also develop crescent formations in the glomeruli, leading to renal failure.