- Clinical science
IgA nephropathy (Berger disease) is the most common primary glomerulonephritis worldwide. It most frequently affects males in the second to third decades of life. Clinical manifestations are usually triggered by upper respiratory tract or gastrointestinal infections and include gross hematuria and flank pain. In some cases, it may present as rapidly progressive glomerulonephritis (RPGN). Urinalysis of asymptomatic patients often shows persistent microhematuria and minor proteinuria, while more severe cases may present with recurrent episodes of nephritic syndrome. A kidney biopsy is necessary to make a definitive diagnosis. Treatment consists of measures to slow the progression of the disease (e.g., ACE-inhibitors), as well as immunosuppressive therapy in more severe cases. Even with the appropriate treatment, up to 50% of the patients progress to end-stage renal disease within 20–25 years.
- The cause is still not entirely understood.
- Most likely mechanism: an increased number of defective circulating IgA antibodies are synthesized (often triggered by mucosal infections, i.e. upper respiratory tract and gastrointestinal infections) → IgA antibodies form immune complexes that deposit in the kidney → glomerulonephritis (type III hypersensitivity reaction)
The course of disease is highly variable. It can present in the following forms:
- Recurring episodes of gross hematuria, flank pain, low-grade fever, and/or nephritic syndrome (including hypertension), usually during or immediately following a respiratory or gastrointestinal infection
- Can progress to RPGN and/or nephrotic syndrome (< 10% of patients)
- Up to 50% of patients progress to end-stage renal disease within 20–25 years.
Diagnosis is based on clinical presentation and laboratory results. In some cases, renal biopsy may be indicated to confirm the diagnosis.
- Signs of microhematuria and possibly minor proteinuria , including persistent
- Episodic flare ups of gross hematuria in half of patients
- In rare cases,
- Usually only indicated if there are signs of severe or progressive disease, including:
- Complement levels (e.g., C3 level) are generally normal.
- Associated with low complement levels
- Occurs 10–20 days following an infection
- Also assoicated with abdominal symptoms, palpable purpura, arthritis
- Patients are usually < 10 years of age
The differential diagnoses listed here are not exhaustive.
- Patients with isolated hematuria: regularly monitor kidney function and initiate treatment if diseases progresses (e.g., occurence of proteinuria)
- Patients with proteinuria or hypertension; : ACE inhibitors/angiotensin II receptor blockers
- For severe/rapidly progressive disease: glucocorticoids + possibly cyclophosphamide/azathioprine