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A. The right suprarenal gland is pyramid-shaped. Its apex projects superiorly, and its base surrounds the kidney. The left suprarenal gland is shaped like a half-moon. It covers the superior aspect of the kidney and extends inferiorly along the medial aspect.

B. The arterial supply is from the inferior phrenic artery via the superior suprarenal artery; the aorta via the middle suprarenal artery; and the renal artery via the inferior suprarenal artery.

C. Venous drainage is to the right suprarenal vein, which empties into the inferior vena cava, and the left suprarenal vein, which empties into the left renal vein. The venous drainage is particularly important during adrenalectomy because the suprarenal vein must be ligated as soon as possible to prevent the release of catecholamines (epinephrine and norepinephrine) into the circulation. In addition, the adrenal medulla receives venous blood that drains from the cortex, which has a high concentration of Cortisol. Synthesis of phenylethanolamine-N-methyltransferase (a key enzyme in the synthesis of epinephrine) requires high levels of Cortisol, which is carried through venous blood from the cortex.

II. ADRENAL CORTEX is derived embryologically from mesoderm and is divided into three areas.

A. Zona glomerulosa accounts for 15% of the cortical volume and secretes aldosterone, which is controlled by the renin-angiotensin system.

B. Zona fasciculata accounts for 78% of the cortical volume and secretes Cortisol, which is controlled by corticotropin-releasing factor (CRF) and adrenocorticotropic hormone (ACTH), from the hypothalamus and the adenohypophysis, respectively.

C. Zona reticularis accounts for 7% of the cortical volume and secretes dehydro-epiandrosterone (DHEA) and androstenedione, which are controlled by CRF and ACTH, from the hypothalamus and adenohypophysis, respectively.

D. Clinical considerations (Table 13-1)

1. Primary hyperaldosteronism a. Cause. Elevated levels of aldosterone most commonly are caused by an aldos-terone-secreting adenoma (Conn syndrome) within the zona glomerulosa or by adrenal hyperplasia.

b. Clinical findings include: hypertension, hypernatremia as a result of increased sodium ion reabsorption, weight gain as a result of water retention, hypokalemia because of increased potassium secretion, and decreased plasma renin levels.

Table 13-1.

Laboratory Findings Used to Diagnose Adrenal Gland Disorders'

Table 13-1.

Laboratory Findings Used to Diagnose Adrenal Gland Disorders'

Clinical Condition

Suppression with

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