Metabolic acidosis is the condition in which Body pH increases due to decrease in HCO3. There are two major pathology either body losses excessive HCO3 or body produce too much Acid (H+ ions). The causes are classified on the basis of anion gap ( normal 3-11 mEq/l) 1. High Anion gap (>12 mEq/l) Metabolic acidosis: when body produce excessive acid (H+ ions). It includes lactic acidosis, Diabetic ketoacidosis, Methanol poisoning, iron and isoniazid poisoning, Uremic phase of renal failure, Ethynole poisoning and salicylate overdose. 2. Normal Anion gap Metabolic acidosis: it includes chronic diarrhea, Renal tubular acidosis type 2, Nutritional therapy, Addison's disease, Acetazolamide, Normal saline, spirolactone.