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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
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
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Gross hematuria, frequently associated with a mucosal viral infection often of the 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
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Can present anywhere along the nephritic spectrum from asymptomatic microscopic hematuria with minimal proteinuria and preserved eGFR to RPGN
Rarely, nephrotic syndrome can occur, as well
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
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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