Lab - Vit B6 Def Flashcards
Xanthurenc acid is an abnormal metabolite of what amino acid?
Tryptophan
The conc of xanthurenic acid in urine is determined by procedure involving formation of ___
Green ferric salt
Final product of tryptophan load test is formed in _ medium
Alkaline
Spectrophotometer value for procedure
610 nm
In unknown tube, there is dH2O, urine and buffer + ___
1.7% ferric ammonium sulfate
Measured in urine in the expt
Xanthurenic acid
coenzyme formed fr B6, that participates in over 60 diff enzyme systems
pyridoxal phosphate
two drugs that may have antagonistic effect with B6: enumerate
isoniazid
oral contraceptive agents
measurement of xanthurenic acid follows a loading with __
tryptophan
Enumerate 3 other tryptophan intermediate metabolites, aside from xanthurenic acid
3-hydroxykynurenine
kynurenine
kynurenic acid
normal metab process: tryptophan ends up as __
nicotinic acid ribonucleotide
enzyme responsible for turning kynurenine into
kynurenic acid
kynurenine aminotransferase
enzyme responsible for turning kynurenine into
3-hydroxyurenine
hydroxylase
enzyme responsible for turning
3-hydroxyurenine into xanthurenic acid
kynurenine aminotransferase
in tryptophan load test, enumerate 2 substances that can be used as preservatives of urine
toluene
oxalic acid
after collecting 24h urine sample, what is given via oral admin?
L-tryptophan OR DL-tryptophan
__ mg for 6 hour urine collection
__mg for 24 hour urine collection
> __ mg/day net increase
Fill in the blanks: abnormal xanthurenic acid excretion
25
100-500
25
name 3 other biochem techniques that can be used to assess Vit B6
urine excretion of free VitB6
urine excretion of 4-pyridoxic acid
erythrocyte transaminase activities
If B6 deficiency is indicated as result of tryptophan load test, oral admin of ____ daily for 7 days should reduce xanthurenic acid excretion to almost normal amounts
15 mg pyridoxine
