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Urinary Casts




Features


  • Cylindrical structures
  • Composed of Tamm-Horsfall mucoprotein
  • Formed in the tubular lumen of the distal nephron
  • Some casts are benign while others may indicate significant renal disease
  • Casts are characterized by the types of cells or elements which they contain

Types and Clinical Associations


  • Red blood cell casts: suggestive of glomerular hematuria and underlying glomerular nephritis
  • White blood cell casts: interstitial nephritis; pyelonephritis
  • Renal tubular epithelial cell: acute tubular necrosis (ATN); interstitial nephritis; toxic ingestion; conditions associated with tubular damage and desquamation
  • Broad or waxy casts: chronic renal failure
  • Hyaline casts: have a transparent, empty appearance – associated with exercise, diuretic therapy, and concentrated urine
  • Fatty casts: contain oval bodies – associated with nephrotic syndrome
  • Granular casts: represent degenerated cellular casts or the aggregation of proteins within a cast matrix – associated with chronic renal failure; muddy brown casts – ATN