About 50% present with recurrent episodes of visible hematuria after an upper respiratory tract infection or gastroenteritis; approximately one third of patients have invisible hematuria and mild proteinuria.
Less than 10% present with either nephrotic syndrome or acute rapidly progressive glomerulonephritis.
Acute or chronic renal failure may develop.
Renal biopsy is required for definitive diagnosis.
Light microscopy shows focal or diffuse mesangial proliferation and extracellular matrix expansion.
Immunofluorescence shows diffuse mesangial IgA deposition in a granular pattern.
ACE inhibitors are widely used to reduce proteinuria, particularly if hypertension and/or proteinuria is present, and they have been shown to help preserve renal function.
The value of immunosuppression in IgAN is widely debated. There is some evidence that early corticosteroid treatment may reduce the severity of proteinuria and delay renal deterioration in people with moderate proteinuria, but this may be associated with serious adverse effects.
IgA nephropathy (IgAN) is defined by the presence of dominant or co-dominant mesangial IgA immune deposits, often accompanied by C3 and IgG in association with a mesangial proliferative glomerulonephritis of varying severity. The etiology of this common glomerulonephritis remains unknown. Clinical presentation varies widely. Patients commonly present with recurrent episodes of visible hematuria (usually occurring after an upper respiratory tract infection or gastroenteritis) or asymptomatic invisible hematuria with or without proteinuria. Less commonly, patients may present with established chronic kidney disease, nephrotic syndrome, malignant hypertension, or a rapidly progressive glomerulonephritis. 
The Mayer Professor of Renal Medicine
Department of Infection, Immunity & Inflammation
University of Leicester
Honorary Consultant Nephrologist
John Walls Renal Unit
Leicester General Hospital
Head of the Postgraduate Specialty School of Clinical Academic Training
Health Education East Midlands
JB has consultancies with Kancera AB, AduroBiotech, Anthera Pharmaceuticals, Calliditas, Novartis, Omeros, and EMD Serono. He is also an author of a number of references cited in this monograph.
Adjunct Assistant Professor
Deputy Head & Consultant
Department of Renal Medicine
Tan Tock Seng Hospital
SCY is an author of a reference cited in this monograph.
Dr Jonathan Barratt and Dr See Cheng Yeo would like to gratefully acknowledge Dr Hani Bleibel and Dr Chike Nzerue, previous contributors to this monograph. HB and CN declare that they have no competing interests.
Associate Professor of Medicine
Stanford University Medical Center
RL declares that he has no competing interests.
Professor of Nephrology
UCL Centre for Nephrology
Royal Free Hospital
AS declares that he has no competing interests.
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