a van Slyke type of osmolality calculation
this is different from the common form of calculating serum osmolality. the reasoning behind this is that virtually all the
kations are small entities with an osmolality of 1osmol/ mol and tend to be accompanied by an equal number of small anions,
with the important execption of the anionic charge of albumin, which is why this charge is substracted from the doubled sum of
the kationic osmolar contribution.
Donald van Slyke put it like this, in 1923: osmolality in plasma water is 2[BA]+[BP], where
BA represents "base" - meaning kations in that time's terminology - accompanied by small molecular anions,
and BP corresponds to "base" accompanied by protein anionic moieties.
Studies of Gas and Electrolyte Equilibria in The Blood, part 5: Factors Controlling the Electrolyte and Water Distribution in The Blood,
J. Biol. Chem., Jul 1923; 56: 765 - 849, the specific reference being to page 778
