Typical Age of Presentation of IgA Nephropathy
IgA nephropathy typically presents in young adults with a mean age at diagnosis of 34 to 45 years, though it can affect individuals across all age groups, most commonly between 10 and 40 years of age 1, 2.
Age Distribution and Epidemiology
The disease predominantly affects younger adults, with the median age at diagnosis reported as 35 to 37 years 3. However, the actual age at presentation varies considerably:
Important Clinical Context
Late Diagnosis is Common
A critical caveat is that many patients are diagnosed much later than disease onset. In a large US cohort, the mean age at biopsy was 47.7 years, with 74.6% of patients already at CKD stage ≥3 at diagnosis 3. This suggests that while the disease likely begins in younger adults, it often goes undetected until significant kidney damage has occurred.
Elderly Presentation
While less common, IgAN can present in patients ≥60 years old 4, 5. These elderly patients typically have:
- More advanced kidney disease at presentation (median eGFR 29.5 mL/min/1.73 m²) 5
- Higher proteinuria levels
- More severe chronic histologic changes
- Worse prognosis (>70% develop ESRD within 20 years) 4
- Higher comorbidity burden 5
Geographic Variation
The incidence is highest in East Asia 1, which may influence age distribution patterns in different populations.
Clinical Presentation by Age
Approximately 60% of cases are detected incidentally with asymptomatic hematuria or proteinuria on urinalysis 1. Up to 30% present with episodic visible hematuria, often concurrent with upper respiratory infections (synpharyngitic hematuria) 1. This classic presentation is more typical in younger patients.
The 2025 KDIGO guidelines now recommend a more liberal biopsy policy, suggesting kidney biopsy in all adults with proteinuria ≥0.5 g/day when IgAN is suspected 6, which may lead to earlier diagnosis in the future.