URINARY CASTS

1. Hyaline casts: heavy albumuria or dehydration
2. Fatty casts: heavy proteinuria; casts consist of tubule cells full of cholesterol; look like "Maltese cross" in polarized light; in free urine these cells are called "oval fat bodies"
3. Waxy casts: degenerated epithelial cells or WBC; characteristic of chronic, progressive renal disease
4. Broad casts: from big nephrons (occur with decreased renal mass)
5. RBC casts: suggest glomerulonephritis and small-vessel vasculitides; rarely seen in interstitial nephritides and ATN
6. Epithelial and WBC casts: suggest interstitial nephritis (esp. if eosinophiluria present), pyelonephritis, ATN (us. see pigmented coarsely granular casts), transplant rejection, any nephronal inflammation
7. Uric acid crystals: suggest tumor lysis syndroma
8. Calcium oxalate crystals: suggest Gi diseases, B6 deficiency, congenital hyperoxaluria, or toxicity with glycol or penthrane
9. Bland sediment: occurs with large-vessel vasculitides, as well as scleroderma and HUS