The image below represents different casts seen in urine at the same
magnification and lighting. Shown are hyaline, hyaline casts with adherent fat, granular and waxy
Cellular casts: These have distinct cells within the protein matrix - if the cells are of epithelial origin (i.e., not WBCs or RBCs), they are called epithelial casts..
Granular casts: As cells within the protein cast matrix break down, the cast becomes coarsely then finely granular.
Waxy casts: Waxy casts are the final stage of cast degeneration (usually originating from cellular and granular casts). Compared to hyaline casts, they are readily observable because they have a smooth appearance, no internal texture, and are more refractile than the surrounding urine.
Of all these casts, hyaline (with or without adherent fat) and finely granular casts may be seen in urine from healthy animals. Cellular, coarsely granular and waxy casts always indicate renal pathology. For more information on the meaning of casts, view the routine urinalysis section.