Criteria for Assessment of Renal Damage
| Grade | Criteria |
| 0 | No irregularities |
| 1 | Little dilatation of tubules; no basal membrane thickening |
| 2 | Criteria as for grade 1, but more pronounced tubule dilatation, basal membrane thickening, and mitotic activity |
| 3 | Shrinkage of small number of glomeruli; flat or lost tubule epithelium, strong tubule dilatation, and more pronounced basal membrane thickening |
| 4 | Increased shrinkage of glomeruli leading to optical emptiness; strongly dilated tubules and signs of peripheral fibrosis |