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The adrenal cortex produces many steroid hormones of which the most important are cortisol, aldosterone, and the adrenal androgens. Disorders of the adrenal glands lead to classic endocrinopathies such as Cushing syndrome, Addison disease, hyperaldosteronism, and the syndromes of congenital adrenal hyperplasia. This chapter describes the physiology and disorders of the glucocorticoids and the adrenal androgens. Disorders of aldosterone secretion are discussed in Chapter 10 and congenital defects in adrenal hormone biosynthesis in Chapters 10 and 14. Hirsutism and virilization (which reflect excess androgen action) are discussed in Chapter 13.
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Advances in diagnostic procedures have simplified the evaluation of adrenocortical disorders; in particular, the assay of plasma glucocorticoids, androgens, and adrenocorticotropin (ACTH) has allowed more rapid and precise diagnosis. Recent discoveries have also begun to elucidate the genetic basis for many disorders of the adrenal cortex, and advances in surgical and medical treatment have improved the outlook for patients with these disorders.
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EMBRYOLOGY AND ANATOMY
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The adrenal cortex is of mesodermal origin and derives from a single cell lineage characterized by expression of certain transcription factors such as steroidogenic factor-1 (SF-1). At 2 months’ gestation, the cortex, already identifiable as a separate organ, is composed of a fetal zone and a definitive zone similar to the adult adrenal cortex. The adrenal cortex then increases rapidly in size; at mid gestation, it is considerably larger than the kidney and much larger than the adult gland in relation to total body mass. The fetal zone makes up the bulk of the weight of the adrenal cortex at this time. Several genes encoding transcription factors are important in adrenal development and differentiation. These include SF-1 and the product of the dosage-sensitive sex reversal–adrenal hypoplasia gene (DAX1), among others; mutations of the DAX1 gene are associated with congenital adrenal hypoplasia.
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The fetal adrenal is under the control of ACTH ...