On Nov 28 , at 2:19 PM, Martin Vlietstra wrote:
In the UK (my blood sugar level) is measured in mol/L.
However, when I was working in Germany, it was measured in mg/dL. I
can see
two advantages of mg/dL ...
This is not just a matter of deciding which unit has "advantages" over
the other; the units "mg/dL" measures something different from what is
measured in "mol/L". It's like arguing that bushels are better or
worse than pounds when buying potatoes. Bushels measures volume while
pounds measures mass. One tells you how much space the potatoes occupy
while the other tells how much mass (and indirectly, weight) they have.
In the case of the blood sugar level, there are two DIFFERENT things
that can be measured.
One is the mass concentration of the sugar, which is related to the
mass of the sugar therein, That is important if you need to know how
heavy it is. This is important primarily if you want to know how the
mass of sugar in the blood contributes to the total body mass of the
individual, which effect is insignificant.
The other thing is the molar concentration of the sugar. That is
related to the number of molecule of sugar that are available for
chemical reactions in the body. This is more closely related to the
effect of the sugar on the body and its value is significant for the
body's functioning.
Although the molar quantity is more important, it is true that, for a
given substance (say, sugar*), a specific molar amount has a specific
(and known) amount of mass. Furthermore, for some diagnostic or
experimental procedures, it would be more convenient to measure the
amount of sugar by its mass (in grams) instead of by its molar amount.
Therefore, for the sake of keeping track of it, either one would do.
Regards,
Bill Hooper
*OK, you'd have to specify the kind of sugar, but that just proves my
point. The molar value would be the same regardless of the kind of
sugars involved. That fact does not mean that one is better than the
other, it just proves that they are different things.
