Chapter

Immunoglobulin A nephropathy and Henoch–Schönlein purpura

Jonathan Barratt and John Feehally

in Oxford Textbook of Medicine

Published on behalf of Oxford University Press

Published in print May 2010 | ISBN: 9780199204854
Published online May 2011 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.210801_update_001
Immunoglobulin A nephropathy and Henoch–Schönlein purpura

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Immunoglobulin A nephropathy (IgAN) is the commonest pattern of glomerulonephritis identified in areas of the world where renal biopsy is widely practised. It is defined pathologically by IgA deposition in the glomerular mesangium accompanied by a mesangial proliferative glomerulonephritis which may vary greatly in severity. Aetiology is uncertain, but abnormalities of IgA1 hinge-region O-glycosylation are consistently found.

Clinical features—IgAN can present with: (1) macroscopic haematuria, typically in children and young adults, developing within a day or two of upper respiratory tract infection (‘synpharyngitic’); (2) asymptomatic microscopic haematuria/proteinuria; (3) nephrotic syndrome (less than 5% of cases); (4) acute kidney injury (uncommon); and (5) chronic renal failure with up to 25% of patients reaching endstage renal failure within 20 years of diagnosis. Henoch–Schönlein purpura (HSP) is a small vessel systemic vasculitis characterized by small blood vessel deposition of IgA that predominantly affects the skin, joints, gut, and kidney, with nephritis that may be histologically indistinguishable from IgA nephropathy.

Management—there is no treatment known to modify mesangial deposition of IgA. Treatment options are mostly directed at controlling blood pressure and limiting proteinuria through blockade of the renin–angiotensin–aldosterone axis. In the rare patient presenting with acute kidney injury in whom biopsy shows crescentic IgA nephropathy, a regimen such as those used for renal vasculitis and other forms of crescentic glomerulonephritis should be considered, e.g. oral prednisolone in combination with cyclophosphamide.

Chapter.  4917 words.  Illustrated.

Subjects: Nephrology

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