Casts Flashcards
Cast structure
Parallel sides
Rounded ends
sometimes fragmented
Cast composition
Uromodulin
excreted by RTE cells
gels to form a matrix
not detected on a reagent test strip
Cast formation process
Tamm-horsfall protein aggregates
fibrils for loose network
further interweaveing forms a Matrix
cast detaches from the RTEs and is excreted
Cast formation conditions
Urinary stasis
acidic pH
increased electrolytes
Hyaline casts
Most frequent.
Formed in: LoH, distal tube, collecting duct
normal: 0-2/lpf
Non-patho: strenuous excersize, dehydration, heat exposure
patho: acute glomerulonephritis, pyelonephritis, chronic renal disease, congestive heart failure
Hyaline cast appearence
Parallel sides with rounded ends
few components in matrix if any
RBC cast
RBCs imbedded in the matrix
non-patho: rarely strenuous exercise
Path: bleeding in the nephron, glomerulornephritis
RBC cast appearance
Methemoglobin breakdown - Brownish color
Hemoglobinuria - orange red to red brown
WBC cast
WBCs (PMNs) trapped in the matrix
Pathologic: infection or inflam in the nephron
Pyelonephritis: upper UTI. Bacteria may be significant
Acute interstitial nephritis. Bacteria absent, may see Eosinophils
Glomerular nephritis
Cystitis does NOT produce WBC casts
bacterial casts
Associated with pyelonephritis
WBC and free bacteria present
Very rare - confirm with gram stain
RTE casts
Very serious, very rare
Tubular destruction
differentiate from WBC cast with stains
Fatty/Oval fat body cast
refractile
stain with sudan III or oil red O
cholesterol -> maltese cross
Will not stain with sternheimer-malbin
Fatty/oval fat body cast pathogenicity
Lipiduria
Nephrotic syndrom
tubular necrosis
crush injuries
Mixed cell casts
ID difficult without staining
Common types:
RBC and WBC: glomerularnephritis
WBC and RTE: pyelonephritis
granular cast
Cellular materials degrade to form granules
Most common: from RTEs
Coarse to fine
REQUIRES urinary stasis
Waxy cast
It’s a waxy cast
long term urinary stasis
Chronic renal failure
Seen along with other casts - long term breakdown of other materials
Waxy cast appearance
Brittle & high refractive index
fragmented or squared ends
stain dark pink
Notches on sides
Broad cast
“Renal failure cast”
2-6x wider than other casts
very long urinary stasis, can form of any other cast
Ways Broad casts form
Dilation or destruction of distal tube walls (causes expansion)
collecting ducts - severe decrease in renal flow
