Hello
Our lab is currently using direct method (ie no pretreatment)for the
quantitative determination of HDL-cholesterol in human.Basically, the
cholesterol enzymes are modified by PEG to give an increased catalytic
activities towards HDL in favour to VLDL and LDL. Then in the presence of
Magnesium ions, a-cyclodextrin in the reagent further reduces the
reactivity of cholesterol.
EDTA is not recommended because it chelates the magnesium in the reagent,
however if that is the case then one would expect an increased in HDL-C
results due to less sensitivity in the reaction, but instead a lower value
is found compare to those in serum.
Can anyone help me in explaining what's is going on?
Many thanks
Kelvin.
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