RD: Roles of the liver and kidney in acid-base regulation and its disorders

The past 15 years have produced some surprising reinterpretations of the mechanisms of acid-base regulation and of the biochemical pathogenesis of metabolic acid—base disorders. Several well es-tablished concepts have been questioned, with possible eventual consequences for clinical man-agement. The purpose of this review is to summarize some of this newer thinking and its implications. Probably the best starting point is the Hen-derson-Hasselbalch equation itself. Many text-books have inferred from it that acid-base homeo-stasis can be regarded in simple terms as a joint function of the lungs and kidneys, the former controlling Pco2, the latter plasma [HCO3~], thus ensuring constancy of arterial pH. The rethinking has been centred largely around the possible role of the liver in both acid—base homeostasis and its disorders, and reappraisal of the role of the kidneys, which appear to have a subtler role than the mere excretion of buffered protons