The<unk>  is a representative of the unmeasured<unk> s in the plasma, and is made of negatively charged phosphates, sulfates, organic acids and plasma proteins (including albumin). Rather than measuring all these<unk> s in a patient, an indirect way is to measure the difference of the dominant cation i.e. sodium to the dominant<unk>  i.e. chloride and bicarbonate, with the understanding that the difference in<unk> s is caused due to the unmeasured<unk> s i.e. phosphate, sulfate, and albumin. Chloride and bicarbonate comprise 85% of the<unk> s in the serum. The differential diagnosis of a patient with a metabolic acidosis is broad and can be narrowed and further evaluated by calculating the<unk> . Normal reference range<unk>  is between 3 and 11 meq/L (average 6 meq/L).
Anion gap
Osmolarity
Electrochemical gradient
Membrane potential
Molecular mass
Gas constant
Oxygen Enhancement Ratio
Resistive index