Lab - Vit B6 Def Flashcards Preview

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Flashcards in Lab - Vit B6 Def Deck (19)
1

Xanthurenc acid is an abnormal metabolite of what amino acid?

Tryptophan

2

The conc of xanthurenic acid in urine is determined by procedure involving formation of ___

Green ferric salt

3

Final product of tryptophan load test is formed in _ medium

Alkaline

4

Spectrophotometer value for procedure

610 nm

5

In unknown tube, there is dH2O, urine and buffer + ___

1.7% ferric ammonium sulfate

6

Measured in urine in the expt

Xanthurenic acid

7

coenzyme formed fr B6, that participates in over 60 diff enzyme systems

pyridoxal phosphate

8

two drugs that may have antagonistic effect with B6: enumerate

isoniazid
oral contraceptive agents

9

measurement of xanthurenic acid follows a loading with __

tryptophan

10

Enumerate 3 other tryptophan intermediate metabolites, aside from xanthurenic acid

3-hydroxykynurenine
kynurenine
kynurenic acid

11

normal metab process: tryptophan ends up as __

nicotinic acid ribonucleotide

12

enzyme responsible for turning kynurenine into
kynurenic acid

kynurenine aminotransferase

13

enzyme responsible for turning kynurenine into
3-hydroxyurenine

hydroxylase

14

enzyme responsible for turning
3-hydroxyurenine into xanthurenic acid

kynurenine aminotransferase

15

in tryptophan load test, enumerate 2 substances that can be used as preservatives of urine

toluene
oxalic acid

16

after collecting 24h urine sample, what is given via oral admin?

L-tryptophan OR DL-tryptophan

17

__ 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

18

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

19

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