Normal anion gap metabolic acidosis is seen in:

Law of electroneutrality = Number of cations & anions should be equal in ICF and ECF In ECF, Na+ is main cation, Cl- & HCO3- are main anions. We do not measure all cations & anions, it is measured as + + = + + we can measure all cations but we cannot measure all anions. So, there is a gap created b/w these two sides. This is called Anion gap. Anion gap is calculated as -{ + } = 141 - = 141 - 129 = 12meq/lit +-4(K+) Thus, normal anion gap is 12+- 4 meq/lit. In acidosis conditions; HCO3- decreases & thus anion gap increases except in acidosis conditions in which anion of the acid is Cl- where anion gap will remain normal. In G.I fluid loss, anion gap remains normal.