Thiamin Flashcards
thiamin coenzyme form
TDP: thiamin diphosphate
TPP: thiamin pyrophosphate
thiamin coenzyme role in glycolysis and TCA
energy transformation: removing CO2
which reactions is thiamin involved in as coenzyme
pyruvate dehydrogenase:
pyruvate-> acetylCoA + CO2
AKG dehydrogenase:
aKG -> succinyl CoA + CO2
transketolase: PPP
thiamin non-coenzyme role
membrane and nerve conduction
TTP: thiamin triphosphate
food sources of thiamin
whole grains, seeds/legumes, meat/pork!
enriched in refined grains/cereals
problem with thiamin fortification
destroyed w heat
some raw foods have anti-thiamin factors
RDA thiamin
M: 1.2mg
W: 1.1mg
primary thiamin deficiency
lack of thiamin in diet
- polished rice staple in south east asia
and consume thiamin destroying factor foods: fermented tea and betel nut
and/or: thiaminase (raw fish, raw ferens)
*milk heat can denature enzyme
secondary thiamin deficiency
excess alcohol
alcholics: large doses of thiamin bc ethanol/acl disrupts absorption
ethanol metab needs TDP
liver function declines, can’t make TPP, TTP
wernicke encephalopathy: 90% are alcoholics:
- ocular motor signs, ataxia, deranged mental functions, altered gate
test status for thiamin
static: measures conc in tissue/stores or plasma/urine (transport)
reflects recent intake, if excretion low=intake low
functional: measures use of thiamin, measure impact of not having enough
- RBC transketolase activity stim test
ETKA test
erythrocyte transketolase acitivty test
want to see if an enzyme requiring coenzyme is function at optimal activity
live: test pt’s RBC enzyme activity then give supplement then test weeks later *if activity improves than they didn’t have enough initially
in vitro stim test done in minutes
procedure of ETKA test
isolate RBC or use hemolyzed blood for access to contents of cell/transketolase
measure activity = 100%
Add TPP, measure again x % more activity
determine if stimulated activity
over 20% = marginal deficient
over 25% = deficient
*this is how EAR was determines
