random glucose

I downloaded the common order set from http://loinc.org/usage/orders/common-lab-orders-value-set.xls

Now glucose in blood ( 2339-0 ) has a ranking of 8.

But if you look at the fasting, and post prandial glucose tests, they change to Ser/Plas.

Why the difference?



PS: Is there a common order set for SI unit users?