Anion gap is calculated using sodium, potassium, chloride and bicarbonate results. These tests are part of MBA and electrolyte profiles. APPLICATION: Investigation of aetiology of metabolic acidosis. INTERPRETATION: An increased anion gap is seen in metabolic acidosis due to renal failure, ketoacidosis, lactic acidosis, drug (e.g, salicylate) and methanol toxicity and in any situation where increased accumulation of acidic anions occurs. Metabolic acidosis with a normal anion gap is seen in renal tubular acidosis and in other causes of bicarbonate loss.
