Acid-base, calcium, potassium and aldosterone metabolism in renal tubular acidosis.

Classic renal tubular acidosis is characterized by a primary defect in establishment of a large hydrogen ion gradient across the distal renal tubule. Thus the development of hyperchlorenic metabolic acidosis follows. In addition, hypokalemia results from renal potassium wasting secondary hyperaldosteronism from sodium wasting and contraction of the extracellular fluid. The presenting signs and symptoms are growth retardation, fatigue, periodic paralysis, polyuria, polydipsia, vomiting and constipation as well as nephrocalcinosis and nephrolithiasis. It is suggested that effective treatment with alkali therapy requires markedly higher doses than formerly recommended, and may related to a higher rate of endogenous acid production from (1) intermediary metabolism of sulfur amino acids and organic acids, (2) impaired tubular reabsorption of bicarbonate and (3) hydrogen ion release from hydroxyapatite formation. It is also suggested that acidosis may interfere with vitamin D metabolism and thus play an important role in the pathoetiology of the growth failure in children with this disorder.