The Kidney in Acid-Base Balance

The approach to the pediatric patient with metabolic acidosis should begin with calculation of the serum anion gap. This allows the clinician to place the patient in one of two categories: a normal anion gap acidosis or a high anion gap acidosis. A patient with metabolic alkalosis is similarly categorized by their response to chloride correction as chloride-responsive or chloride-resistant. The disease states associated with each category are reviewed in this article. It should be evident to the clinician that the kidney’s primary role in acid-base metabolism is twofold: recycling of filtered bicarbonate and synthesis of new bicarbonate. The latter is a function of the inducible process of renal ammoniagenesis; the study of the control of this process is an area of active research. Growth failure has long been recognized as a complication of acidosis in children. New insights have emerged on the effect of acidosis on the secretion of growth hormone, as well as its expression at the level of a target organ, the growth plate of the long bone.