Urinary casts are formed in the distal convoluted tubule or the collecting duct by solidification of protein in the lumen of the kidney tubules. This term refers to casts located within the tubuli of the kidney. More precisely, casts are defined as a material that completely fills and expands the tubular lumen with simplification of surrounding tubular epithelium. Casts are classified as either nuclear debris/granular brown material, red blood cell, white blood cell, myeloma, or myoglobin cast. [from
HPO]