Metabolic Acidosis By James L Lewis III, MD, Brookwood Baptist Health and Saint Vincent's Ascension Health, Birmingham Reviewed / Revised Jul 2021 | Modified Sep 2022 View Patient Education Etiology Symptoms and Signs Diagnosis Treatment Key Points Topic Resources Anion Gap Arterial Blood Gas Interpretation... Winter's Formula for Expected.. Urine anion gap Causes of Metabolic Acidosis Overview of Metabolic Acidosis Metabolic acidosis is primary reduction in bicarbonate (HCO 3 −), typically with compensatory reduction in carbon dioxide partial pressure (P co 2); pH may be markedly low or slightly subnormal.