10 - detection of muscle injury

Question 1

(CK)

1. ^ALT greater than ^AST, no ^ CK = ?
2. ^AST greater than ^ALT, ^CK = ?

Answer 1

1. liver injury
2. muscle injury

Question 2

(CK)

1. muscle specific?
2. ^ caused by what?
3. does magnitude of ^ correlate to severity?
4. how long does CK persist?

Answer 2

1. yes (also in brain/nerves but not important)

not observed in CNS injury

2. skeletal/cardiac musc injury, muscle catabolism (esp cats)
3. NO!
4. rapidly increases after injury - back to normal within 24 to 48 hours

Question 3

(AST)

1. present in what?
2. rise/fall when relative to musc injury (and CK)?

Answer 3

1. cytoplasm of hepatocytes, skeletal/cardiac muscle
2. ^ more slowly than CK, persists longer (useful to determine duration w/ CK)

Question 4

(ALT)

1. some elevation may be seen in dogs and cats with musc injury but no hepatic dmg

Question 5

(lactate dehydrogenase - LDH)

1. why non-specific for muscle?

Answer 5

1. located in cytoplasm in most cells

Question 6

(myoglobin)

1. release from dead muscle cells into blood and excreted into urine (dark brown urine)
2. if urine + for hemoglobin on dipstick and serum is colorless/yellow -> ?

if serum red -> ?

why?

Answer 6

2. myglobinuria
3. hemoglobinuria

myoglobin rapidly excreted by kidneys -> serum remains colorless