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Adrenal disorders Main Page
Adrenal or suprarenal glands are important endocrine glands that produce variety of hormones, such as epinephrine, steroids, aldosterone, and cortisol. Each gland consists of an outer capsule, underneath cortex, and the central part called medulla. The cortex is further classified into these layers, each layer produces specific hormone. Congenital adrenal hyperplasia is the disease of adrenal cortex, which is classified into seven types based on the genetic causes that lead to hyperplasia and hormonal imbalance. There are three zones of hormonal synthesis in the adrenal cortex; zona glomerulosa secrets aldosterone, zona fasciculata secrets cortisol, and zona reticularis secrets androgens. Impairment of each pathway and enzyme may lead to a specific subtype of congenital adrenal hyperplasia, such as 21-hydroxylase deficiency, 17 alpha-hydroxylase deficiency, 11β-hydroxylase deficiency, 3 beta-hydroxysteroid dehydrogenase deficiency, cytochrome P450-oxidoreductase (POR) deficiency (ORD), and congenital lipoid adrenal hyperplasia. Another adrenal cortex disease is hyperaldosteronism due to zona glomerulosa hyperplasia. This hyperplasia can be bilaterally or unilateral and may cause aldosterone hypersecresion leading to the classic clinical presentation of aldosteronism, which is resistant hypertension and hypokalemia. The other cortical disease is Cushing's syndrome due to zona fasciculata disease. Cushing's syndrome can classified into two types, ACTH dependent or ACTH independent. In the ACTH dependent type, increasing ACTH secretion from pituitary can cause cortisol hypersecresion. In the ACTH independent form, adenomas, carcinomas, or cortical hyperplasia may lead to increase the cortisol level and hypercortisolism. Adrenal insufficiency is destruction of adrenal cortex, totally or partially. The most common cause of adrenal insufficiency is Addison's disease, which is autoimmune destruction of adrenal cortex. Other causes are tuberculosis, lymphoma, adrenal hemorrhage, and drugs. Acute form of adrenal insufficiency can lead to severe syndrome and presenting with shock. Most of adrenal masses are benign and nonfunctioning adenomas that are discovered incidentally on imaging studies. Adrenal masses can be classified into adrenocortical carcinoma, incidentaloma, pheochromocytoma. Adrenocortical carcinomas are rare, but invasive tumors that can be functional and secrete hormones; or nonfunctional and present as an mass or an incidental finding on imaging studies. Pheochromocytoma is a neuroendocrine tumor arises from chromaffin cells of the adrenal medulla. These tumors secrete excessive amount of catecholamines, mostly epinephrine and norepinephrine. Incidentaloma is another adrenal tumor that often discovered as an incidental finding in ultrasonography. Most incidentalomas are nonfunctional but some of them are found to secrete low levels of cortisol, aldosterone, or catecholamines.