Abstract
We report a case of a patient who had critically low serum bicarbonate (HCO(3) (-)) levels ranging from 8 to 11 mmol/L on repeated venous measurements using an enzymatic/photometric assay. This prompted hospitalization and treatment with intravenous sodium bicarbonate (NaHCO(3)) followed by oral NaHCO(3). He was evaluated for potential causes of high anion gap metabolic acidosis without any etiology found. He continued to have low serum HCO(3) (-) levels despite maintenance oral NaHCO(3) therapy and was referred for a second opinion where further laboratory work was pursued. An arterial blood gas was obtained, which revealed normal whole blood pH and HCO(3) (-) levels. A different enzymatic/photometric assay revealed a normal serum HCO(3) (-) level at 21 mmol/L. Additional workup revealed paraproteinemia, which was thought to interfere with the enzymatic process by which his serum HCO(3) (-) was measured, resulting in erroneous values.