Hypobicarbonatemia is common in patients with chronic kidney disease (CKD) and is almost always attributed to metabolic acidosis rather than respiratory alkalosis. To be sure, one would have to measure pH and Pco2. However, these parameters have infrequently been measured in the outpatient setting partly due to logistical reasons. Because the kidneys are responsible for excreting the nonvolatile acid load, it is reasonable to assume that hypobicarbonatemia represents metabolic acidosis if kidney function is impaired.