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[IP] glucose levels

B Brad and Roselea discuss meter accuracy:
 >Is there a whole lot of difference between the blood being drawn from
a vein in your arm and blood drawn from you finger? Is the 15% difference
to allow for that?<
The whole blood from the vein should have a lower glucose level than the
whole blood from the finger, since the blood from the finger tip is closer
to the capilary whole blood glucose level (the glucose that is taking place
at the cellular level). This should allow for a 15% difference. Double check
with the lab technologist, as I might be a bit off with that explanation.
The 15% is also an allowable difference for the meter accuracy.
Venous blood glucose includes the glucose in the red blood cells which are 
lysed in the laboratory at the start of the analysis process. while our 
meters are analyzing only plasma glucose which does not contain the glucose 
from the red cells. In that fact is the difference. the lab value is a 
whole blood value while the home meters we use are plasma glucose only. the 
glucose sensors made my minimed for the cgms only looks at plasma glucose 
and is in my experience right on the line with the Bayer Glucometer elite 
strips bur those strips are 15% lower than when I test on the Beckman 
Synchron, an automated blood chemistry analyzer. If I check it on the 
Beckman Glucose Analyzer it is right on target because the Beckman Glucose 
meter works on plasma not whole blood. So, the methodology is the same in 
the strips as in the Beckman Analyzer. Glucose oxidase liberates oxygen 
from the glucose in the sample which generates a small electric current 
which is measured by the meter. It is a linear measurement at trhe normal 
glucose range in the blood. when it gets out of that range, the meter will 
register Hi as a way of saying The value is too high to report with 
reliability. The technology has come a long way from boilining an alkaline 
solution of copper sulfate with a preparation made from your whole blood 
and detecting how much of the copper was reduced from cu+++ to cu++ which 
was a rough measure of the amount of glucose and also was the basis for the 
old Clinitest reaction for urine. also took less time and you didn't have 
to pipette Arsenomolybdic acid which was poisonous with your mouth. OSHA 
would have a fit these days. More than you ever wanted to know about 
glucose testing. (cu+++ = cuprous blue, cu++= coupric orange copper 
colored). Spot who still remembers doing those glucose tests on the little 
tots in DKA in the middle of the night when he was a night lab tech at 
Cooper Hospital in dirty corrupt Camden NJ.
A Bender, M. D.
email @ redacted

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