Maintenance of normal acid-base homeostasis is one of the most important kidney functions. In chronic kidney disease, the capacity of the kidneys to excrete the daily acid load as ammonium and titratable acid is impaired, resulting in acid retention and metabolic acidosis. The prevalence of metabolic acidosis increases with declining glomerular filtration rate. Metabolic acidosis is associated with several clinically important complications, including chronic kidney disease progression, bone demineralization, skeletal muscle catabolism, and mortality.