IGA nephropathy has different grading methods, such as Lee grading and Hass grading. Both classify the pathological changes of IGA nephropathy into five stages, with similar descriptions. According to the Lee grading: Grade 1: Most glomeruli are normal, with occasional mild mesangial widening or without cellular proliferation, and no tubulointerstitial changes. Grade 2: Glomeruli show focal mesangial proliferation, with no tubulointerstitial changes. Grade 3: Glomeruli exhibit diffuse mesangial proliferation, with occasional segmental focal lesions, rare crescents, and adhesions, focal interstitial edema, and rare cellular infiltration. Grade 4: Glomeruli show diffuse severe mesangial proliferation and sclerosis, partial or segmental glomerulosclerosis, crescent formation observed but less than 45%, tubular atrophy, interstitial infiltration. Grade 5: The nature of the lesions is similar to grade 4 but more severe. Crescent formation in glomeruli is greater than 45%.