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Key Features

  • Primary renal disease with IgA deposition in the glomerular mesangium

  • Inciting cause unknown but is likely due to deficient O-linked glycosylation of IgA subclass 1 molecules

  • Can be a primary (renal-limited) disease

  • Can be secondary to

    • Hepatic cirrhosis

    • Celiac disease

    • HIV infection

    • Cytomegalovirus infection

  • Most common primary glomerular disease worldwide, particularly in Asia

  • Usually occurs in children and young adults

  • Males affected 2–3 times more often than females

Clinical Findings

  • Gross hematuria, frequently associated with a mucosal viral infection such as an upper respiratory tract infection

  • Urine becomes red or smoky-colored 1–2 days after illness onset

  • Can present anywhere along the nephritic spectrum from asymptomatic microscopic hematuria to rapidly progressive glomerulonephritis

  • Rarely, a nephrotic syndrome can be present as well

Diagnosis

  • Proteinuria: minimal to nephrotic range

  • Glomerular hematuria: microscopic is common; macroscopic (gross) can occur after infection

  • Positive IgA staining on kidney biopsy

  • Serum complement levels usually normal

  • No serologic tests aid in diagnosis; serum IgA subclass 1 testing may be possible in future

  • Renal biopsy

    • Light microscopy shows focal glomerulonephritis with proliferation of mesangial cells

    • Immunofluorescence shows diffuse mesangial IgA and C3 deposits

Treatment

  • Patients with low risk for progression (no hypertension, normal glomerular filtration rate [GFR], minimal proteinuria) can be monitored annually

  • Angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB)

    • Recommended for patients at higher risk for progression (proteinuria > 1.0 g/day, decreased GFR, and/or hypertension)

    • Therapy should be titrated to reduce proteinuria to < 1 g/day and to reduce blood pressure to between 125/75 mm Hg and 130/80 mm Hg

  • Addition of corticosteroids (eg, methylprednisolone, 1 g/day intravenously for 3 days during months 1, 3, and 5, plus prednisone 0.5 mg/kg orally every other day for 6 months) in those with GFR > 50 mL/min/1.73 m2 and persistent proteinuria > 1 g/day

    • Has been shown to reduce proteinuria

    • However, there seems to be little durable effect

    • Risks of infection and dysglycemia are significant

  • Azathioprine and mycophenolate mofetil

    • Have also been used in patients at high-risk for progression

    • However, studies with these agents are small

    • Therefore, routine use is not recommended

  • Cyclophosphamide and corticosteroid therapy should be considered for the rare patient with a rapidly progressive clinical course with crescent formation on biopsy

  • Kidney transplantation

  • ~33% of patients experience spontaneous remission

  • Chronic microscopic hematuria but stable serum creatinine occur in 50–60%; progression to end-stage renal disease occurs in 20–40%

  • Most unfavorable prognostic indicator: proteinuria > 1 g/day

  • Other unfavorable prognostic indicators

    • Hypertension

    • Tubulointerstitial fibrosis

    • Glomerulosclerosis or glomerular crescents on biopsy

    • Abnormal GFR on presentation

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