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Overview :
Activities of blood transaminases, either aspartate (GOT) or
alanine (GPT) aminotransferase, can serve as indications of a patient's vitamin
B6 nutritional status. Enzymatic assays run before and after addition of
pyridoxal phosphate can be used to generate an activity coefficient ratio. This
represents the functional availability of erythrocyte vitamin B6 in its
coenzyme form. Its value increases with vitamin B6 deficiency.
Specimen: Whole blood collected in EDTA. Hemolysate prepared
which is stable for several weeks at -20 C and for up to 10 weeks at -70 C.
Repeated freeze-thaw cycles should be avoided.
Analysis: Erythrocyte glutamate oxaloacetate transaminase
(EGOT, aspartate transaminase) is measured in an erythrocyte hemolysate before
and after stimulation with pyridoxal phosphate (25 µg/mL) for 20 minutes.
EGOT index =
= (GOT of hemolysate after stimulation with pyridoxal
phosphate) / GOT of hemolysate before stimulation with pyridoxal phosphate
where:
• Units for
erythrocyte GOT need to be clarified; probably units per gram hemoglobin
(alternatives: units per 10^12 erythrocytes).
Interpretation:
• The criteria
for interpreting results varies with the amount of pyridoxal phosphate added
and with the method of testing.
• vitamin B6
deficiency: > 1.5
• acceptable B6
levels: < 1.5
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