Metabolic acidosis results from a disequilibrium between production and excretion of acid. Loss of base from the body through the gastrointestinal tract or in the urine or an increase in metabolic acid production are the three major mechanisms from which metabolic acidosis is generated. Uncomplicated metabolic acidosis is manifested by an increase in blood acidity, hypobicarbonatemia, and hypocapnea. The magnitude of these changes defines the severity wf the acidosis. It is convenient to divide metabolic acidosis into two general categories (hyperchloremic and normochloremic), based on the observed anion gap, as this serves to narrow the differential diagnosis. The normal anion gap is that amount of plasma anion not measure by routine laboratory screening that accounts for the difference between the measured sodium cation (Na+) and anions (Cl +/- HCO3-). Metabolic acidosis; causes; diagnosis; clinical manifestations.