microscopic UA pt 2 - casts

Question 1

describe composition of casts

Answer 1

• Tamm-Horsfall glycoprotein (uromodulin)
• excreted at constant rate by RTE cells for mucus lubrication

Question 2

where are casts formed

Answer 2

w/in nephron only
- loop of henle, distal or collecting

Question 3

describe steps of cast formation

Answer 3

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

Question 4

define cylindruria

Answer 4

casts in urine

Question 5

under what conditions does cast formation occur more readily

Answer 5

• urinary stasis
• acidic pH (alkaline dissolves)
• electrolytes increase

Question 6

list the types of casts

Answer 6

• hyaline (most common)
• cellular (red/white cell or RTE)
• fatty
• granular (fine/coarse)
• broad (collecting duct)
• waxy (severe renal stasis)

Question 7

describe hyaline casts

Answer 7

• 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

Question 8

disease associated with RBC casts

Answer 8

• indicates bleeding w/in nephron
• glomerulonephritis

Question 9

how does hemoglobinuria impact RBC casts

Answer 9

casts appear orange-red or red-brown
- acute tubular necrosis (can lead to kidney failure)

Question 10

how does hemoglobin being broken down to methemoglobin impact RBC cast

Answer 10

cast is brownish

Question 11

True or false
Cystis (lower UTI infection) doe NOT produce WBC casts

Answer 11

true
- bladder not nephron

Question 12

list patholoigc associations of WBC casts

Answer 12

• infection or inflammation in nephron
• pyelonephritis
• acute interstitial nephritis
• glomerular nephritis

Question 13

disease association of bacterial casts

Answer 13

pyelonephritis
- WBC and free floating bacteria along w/ cast
- confirmed with gram stain

Question 14

what causes RTE casts

Answer 14

tubular destruction
- confirmed with staining

Question 15

list cellular mixutre cast associated with glomerulonephritis

Answer 15

RBC and WBC

Question 16

list cellular mixture cast associated with pyelonephritis

Answer 16

WBC and RTE

Question 17

what causes granularity in granular casts

Answer 17

urine material degrading
- start coarse then become fine with age
- RTE most common degredation

Question 18

describe formation of waxy casts

Answer 18

• long term urinary stasis
• degredation of granular casts
• seen with other casts

Question 19

association with waxy cast

Answer 19

chronic renal failure

Question 20

describe broad casts

Answer 20

• long long term urinary stasis
• 2-6x wider than normal casts
• formed from any type of cast (generally granular or waxy)

Question 21

describe the two methods of broad cast formations

Answer 21

• distal tubule dilating/destruction causing the tubular walls to be wider
• formation in collecting duct from long term stasis