IgA nephropathy, first descibed in 1968, is the most common form of primary glomerulonephritis in the world. It is an antibody-mediated glomerular disease in which the immune deposits localize to the mesangium. It is not certain whether the deposits form in situ or from circulating immune complexes.
Patients with IgA nephropathy usually present with one of three syndromes:
A less common presentation is with the nephrotic syndrome. These patients may have advanced disease or normal renal function. In the latter case, the light microscopic features are of minimal change disease but with intense mesangial staining for IgA.
A. Morphologic Features
The glomeruli in IgA nephropathy show some degree of mesangial hypercellularity.
Segmental proliferation, sclerosis, and necrosis with crescent formation may also be seen
The diagnosis of IgA nephropathy rests on the demonstration of mesangial deposits of IgA by direct immunofluorescence microscopy; IgG and C3 are variably present.
Ultrastructurally deposits are present in the mesangium, and often have a "paramesangial" location beneath the basement membrane as it covers the mesangium.
B. Clinical Course
Renal function progressively worsens in approximately 40% of patients, about half of whom reach end-stage renal failure after 20 years of clinically apparent disease. Nearly 30% of patients exhibit a benign course with chronic microscopic hematuria, a normal serum creatinine and proteinuria usually less than 1 gram/day. Hypertension is not uncommon and malignant hypertension develops in about 5% of patients.
Secondary deposits of IgA may occur in chronic liver disease, dermatitis herpetiformis, psoriasis, ankylosing spondylitis, celiac disease, inflammatory bowel disease, carcinoma, IgA monoclonal gammopathy, HIV infection and mycosis fungoides.
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Last Modified: February 26, 1997