What is the most likely basis of metabolic acidosis in this patient?
Physiology principle 2. One can deduce that H+ ions have been added when new anions appear in the body and/or in excreted fluids. Return to the bedside: There are two types of metabolic acidosis: a gain of acids and/or a loss of NaHCO3. Therefore if one suspects a gain of acids, one must hunt for the presence of new anions by finding their chemical or electrical shadow . The simplest clinical tool used to detect new anions is a rise in the anion gap in plasma. The rationale is as follows. When an acid is added and dissociates, the H+ ions formed react with HCO3 ions and remove an equimolar amount of this anion. The conjugate base of this acid takes the electrical place of HCO3 ions in the extracellular fluid (ECF) compartment (Figure 1). This 1:1 stoichiometry in mEq/l causes many clinicians to expect that the surplus of new anions (reflected by the rise in the anion gap in plasma) will equal the deficit in HCO3 (reflected by the (PHCO3). This is only correct if there is no change in t
