Aldosterone Deficiency and Resistance

Aldosterone is crucial for regulating sodium conservation in the kidney, salivary glands, sweat glands, and colon. This adrenal steroid hormone acts via the mineralocorticoid receptor (MR) to promote active transport of sodium and potassium excretion in its target tissues, through activation of specific amiloride-sensitive sodium channels (ENaC) and a Na-K ATP-ase pump. Defective aldosterone biosynthesis or action results in various clinical and laboratory test manifestations, such as hypotension, hyponatremia, hyperkalemia, and acidosis. Primary adrenal insufficiency and congenital adrenal hypoplasia are discussed in other chapters. In this chapter the mechanisms underlying aldosterone-deficient conditions, such as hyporeninemic hypoaldosteronism, primary hypoaldosteronism, including aldosterone synthase deficiency (ASD), acquired forms of the disease, and pseudohypoaldosteronism, an aldosterone resistance syndrome due to insensitivity of target tissues to aldosterone, are reviewed. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG .