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Hypertension affects one in four adults in the developed world. Although hypertension is essential or idiopathic in most cases, a cause can be detected in approximately 15% of the hypertensive population. The secondary causes of hypertension can be divided into renal (eg, renal vascular or parenchymal disease) and endocrine causes. There are at least 14 endocrine disorders in which hypertension may be the initial clinical presentation (Table 10–1). The diagnosis of endocrine hypertension presents the clinician an opportunity to provide a surgical cure or to achieve a marked response with targeted pharmacologic therapy. Pheochromocytoma and Cushing syndrome are reviewed in detail in Chapters 11 and 9, respectively. The renin-angiotensin-aldosterone system, the diagnostic and therapeutic approaches to mineralocorticoid hypertension (eg, primary aldosteronism), and less common forms of endocrine hypertension are reviewed in this chapter.
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RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM
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The components of the renin-angiotensin-aldosterone system are shown in Figure 10–1. Aldosterone is secreted from the zona glomerulosa under the primary control of angiotensin II, potassium, and corticotropin (ACTH). The secretion of aldosterone is restricted to the zona glomerulosa because of zonal-specific expression of aldosterone synthase (CYP11B2). Hypokalemia, atrial natriuretic peptide (ANP), dopamine, and heparin inhibit aldosterone secretion.
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Renin and Angiotensin
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Renin is an enzyme produced in the juxtaglomerular apparatus of the kidney, stored in granules, and released in response to specific secretagogues. The first 43 amino acids of the 340 amino acid renin protein are a prosegment cleaved to produce the active enzyme. The release of renin into the circulation is the rate-limiting step in the activation of ...