IgA Nephropathy

IgA detected in glomerular mesangium by immunoflourescence

Wyatt and Julian had a review of IgA nephropathy (IgAN) in NEJM. The disease is now regarded as having autoimmune in origin. Abnormal immunoglobulin A molecule in the form of galactose-deficient IgA1 is the main etiology. The formation of immune complex between this molecule and anti-glycan antibody and deposition in the glomeruli are needed
for the pathogenesis. Then the immune complex activates mesangial cells in glomerulus to secrete more extracellular matrix and mediators such as angiotensin II responsible for glomerular injury.

Genetics play an important role in determining whether a person will have high level of galactose-deficient IgA1 and lack of protective genes. However, the high level of galactose-deficient IgA1 is not diagnostic of IgAN. Urine proteomics seems to have potential use as diagnostic tool in addition to renal biopsy.

The clinical outcome depends on amount of proteinuria, hypertension and pathologic findings. Oxford classification had been proven to have prognostic value, especially regarding tubular atrophy and interstitial fibrosis.

Currently there is no treatment targeting etiology of the disease. The principal treatment is ACE inhibitor or angiotensin II receptor blocker (ARB) to decrease blood pressure and proteinuria. Immunosuppressive drugs are reserved in patients with crescents in more than half of glomeruli in the biopsy and rapid deterioration in renal function.