ABSTRACT
A young man who presented with fever, altered sensorium and sudden onset tachypnea, is described. Arterial blood gas analysis, revealed the presence of severe high anion gap metabolic acidosis, with compensatory respiratory alkalosis and normal oxygen saturation. A detailed neurological, nephrological, biochemical and hematological evaluation, revealed the presence of Acute myeloid leukemia, with lactic acidosis and hyponatremia. There are very few reports of presentation of leukemia as lactic acidosis. This case report highlights the need for emergency room physicians, to consider the possibility of lactic acidosis, as one of the causes of high anion gap acidosis and to meticulously investigate the cause of lactic acidosis. We describe a rare clinical instance of lactic acidosis as the presenting manifestation of Acute myeloid leukemia.