microscopic UA pt 2 - casts Flashcards
describe composition of casts
- Tamm-Horsfall glycoprotein (uromodulin)
- excreted at constant rate by RTE cells for mucus lubrication
where are casts formed
w/in nephron only
- loop of henle, distal or collecting
describe steps of cast formation
1) Tamm-Horsfall aggregates to RTE to form loose fibriles
2) fibrils traps components in urine
3) further interweaving of fibrils forms SOLID structure - matrix
4) urine components attach to matrix
5) cast detaches from RTR and exits the nephron
define cylindruria
casts in urine
under what conditions does cast formation occur more readily
- urinary stasis
- acidic pH (alkaline dissolves)
- electrolytes increase
list the types of casts
- hyaline (most common)
- cellular (red/white cell or RTE)
- fatty
- granular (fine/coarse)
- broad (collecting duct)
- waxy (severe renal stasis)
describe hyaline casts
- loop of henle (pig tailed), distal or collecting
- normal: 0-2/lpf
- non patho: exercise, dehydration
- patho: acute glomerulonephritis, pyelonephritis, chronic renal disease or CHF
disease associated with RBC casts
- indicates bleeding w/in nephron
- glomerulonephritis
how does hemoglobinuria impact RBC casts
casts appear orange-red or red-brown
- acute tubular necrosis (can lead to kidney failure)
how does hemoglobin being broken down to methemoglobin impact RBC cast
cast is brownish
True or false
Cystis (lower UTI infection) doe NOT produce WBC casts
true
- bladder not nephron
list patholoigc associations of WBC casts
- infection or inflammation in nephron
- pyelonephritis
- acute interstitial nephritis
- glomerular nephritis
disease association of bacterial casts
pyelonephritis
- WBC and free floating bacteria along w/ cast
- confirmed with gram stain
what causes RTE casts
tubular destruction
- confirmed with staining
list cellular mixutre cast associated with glomerulonephritis
RBC and WBC
list cellular mixture cast associated with pyelonephritis
WBC and RTE
what causes granularity in granular casts
urine material degrading
- start coarse then become fine with age
- RTE most common degredation
describe formation of waxy casts
- long term urinary stasis
- degredation of granular casts
- seen with other casts
association with waxy cast
chronic renal failure
describe broad casts
- long long term urinary stasis
- 2-6x wider than normal casts
- formed from any type of cast (generally granular or waxy)
describe the two methods of broad cast formations
- distal tubule dilating/destruction causing the tubular walls to be wider
- formation in collecting duct from long term stasis
