IgA Nephropathy: Signs and Symptoms
IgA nephropathy most commonly presents with asymptomatic microscopic hematuria and proteinuria detected incidentally on urinalysis, occurring in approximately 60% of cases 1.
Clinical Presentation Spectrum
The clinical manifestations of IgAN range from subtle laboratory abnormalities to severe kidney injury, with distinct patterns that guide diagnosis and risk stratification:
Most Common Presentations
Asymptomatic microscopic hematuria with proteinuria (60% of cases): Detected incidentally during routine urinalysis, often in young adults aged 34-45 years 1
Episodic visible (gross) hematuria (up to 30% of cases): Characteristically occurs concurrently with upper respiratory or gastrointestinal infections—termed "synpharyngitic hematuria"—representing a pathognomonic feature when present 1. This painless macrohematuria typically appears during or immediately after mucosal infections 2, 3
Less Common but Critical Presentations
Nephrotic syndrome (<5% of cases): Rare presentation requiring differentiation between true IgAN variant versus coexistent minimal change disease 4, 1
**Rapidly progressive glomerulonephritis (<5% of cases)**: Defined as ≥50% decline in eGFR over ≤3 months, typically associated with extensive crescent formation (usually >50% of glomeruli), often occurring without visible hematuria 4, 5
Acute kidney injury: Can occur from severe visible hematuria episodes or from rapidly progressive disease 5
Key Clinical Findings
Urinary Abnormalities
- Nephritic urinary sediment: Erythrocytes, acanthocytes (dysmorphic red blood cells), and erythrocyte casts 2
- Proteinuria: Variable severity, from trace amounts to nephrotic range (>3.5 g/day)
- Persistent proteinuria >1 g/24h: Identifies high-risk patients requiring treatment consideration 5
Systemic Manifestations
- Hypertension: Common finding at presentation 2, 3
- Reduced kidney function: May be present at diagnosis or develop progressively
- Systemic inflammatory markers: Significantly associated with disease activity 6
Important Clinical Caveats
The diagnosis of IgAN cannot be made clinically and requires kidney biopsy confirmation 2, 3. Adults with suspected IgAN and proteinuria ≥0.5 g/day should undergo kidney biopsy 1.
Pitfalls to Avoid
Do not assume all hematuria with IgA deposits is primary IgAN: Must exclude secondary causes including IgA vasculitis, infection-related glomerulonephritis, cirrhosis, inflammatory bowel disease, celiac disease, viral hepatitis, and autoimmune diseases 1, 2
Crescents without GFR decline do not constitute rapidly progressive IgAN: These patients require close monitoring but different management than true RPGN 5
Nephrotic-range proteinuria without nephrotic syndrome: Often reflects coexistent secondary focal segmental glomerulosclerosis from obesity or uncontrolled hypertension, or extensive glomerulosclerosis from chronic damage 4, 5
Disease Trajectory
IgAN is now recognized as a relentlessly progressive disease rather than slow-moving, with up to 50% of patients developing kidney failure within 10 years of diagnosis 1. The disease can present with active lesions that may remit but also relapse at any stage, often triggered by mucosal infections or vaccinations 6. Without adequate treatment, 20-40% of patients progress to end-stage renal disease within 20-30 years 7, 3.