The measurement in laboratory tests must be the same every time and in every place. Your physician must be able to rely on a known and accepted standard. Different units of measure are used depending on the substance being measured. Normally, in Blood laboratory testing the metric system is used to measure mass, volume, and length. Liters are the standard to express measurement of volume, the amount of space that an object occupies.
Meters are the standard to express measurement of length.
One great convenience of the metric is that it is based on multiples of 10. Another is that it is accepted universally around the world. Other units of measure communicate different measured properties of a substance. However, the number of grams in 1 mole may vary greatly from substance to substance. For example, the molecular weight of calcium is 40, and 1 mole of calcium equals 40 grams.