Adrenal Disorders — Cushings Syndrome

Late-onset adrenal hyperplasia Cushing s syndrome Virilizing adrenal tumors Adrenocorticoid insufficiency Thyroid disorders Hypothyroidism Hyperthyroidism Pituitary disorders... 

Hyperfunction of the adrenal glands occurs in Cushing s syndrome, a disorder caused by excessive secretion of cortisol by the adrenal gland (hypercortisolism). Other causes of adrenal gland hyperfunction include primary and secondary aldosteronism (not discussed in this chapter refer to textbook Chap. 79 for more information on these disorders). 

Several relatively common disorders result in aldosterone secretion abnormalities and aberrations of electrolyte status. In Addison s disease, the adrenal cortex is often destroyed through autoimmune processes. One of the effects is a lack of aldosterone secretion and decreased Na+ retention by the patient. In a typical Addison s disease patient, serum [Na+] and [CL] are 128 and 96 meq/L, respectively (see Table 16.2 for normal values). Potassium levels are elevated, 6 meq/L or higher, because the Na+ reabsorption system of the kidney, which is under aldosterone control, moves K+ into the urine just as it moves Na+ back into plasma. Thus, if more Na+ is excreted, more K+ is reabsorbed. Bicarbonate remains relatively normal. The opposite situation prevails in Cushing s disease, however, in which an overproduction of adrenocorticosteroids, especially cortisol, is present. Glucocorticoids have mild mineralocorticoid activities, but ACTH also increases aldosterone secretion. This may be caused by an oversecretion of ACTH by a tumor or by adrenal hyperplasia or tumors. Serum sodium in Cushing s disease is slightly elevated, [K+] is below normal (hypokalemia), and metabolic alkalosis is present. The patient is usually hypertensive. A more severe electrolyte abnormality is seen in Conn s syndrome or primary aldosteronism, usually caused by an adrenal tumor. Increased blood aldosterone levels result in the urinary loss of K+ and H+, retention of Na+ (hypernatremia), alkalosis, and profound hypertension. 

Cushing s syndrome is an uncommon disorder but many of the usual signs and symptoms of this syndrome are seen in patients with normal adrenal function. The initial diagnosis of Cushing s syndrome, particularly in mild or early disease, rests on laboratory evidence of excessive and autonomous cortisol production. Two simple screening tests are... 

Congenital adrenal hyperplasia Congestive heart failure Chromosome disorders Chromosome mosaicism Chromosome translocation Copper excess Cri-du-chat syndrome Crouzon s syndrome Cushing s syndrome Cyanide poisoning Cystic fibrosis Diabetes insipidus Diabetes mellitus Dinitrophenol poisoning Diphtheria... 

There are several disorders of the adrenal glands. Hypersecretion of aldosterone (Conn s syndrome) is treated with an aldosterone antagonist. Hypersecretion of cortisol (Cushing s syndrome) and testosterone (androgenital syndrome) are managed with surgery or irradiation. Hyposecretion of aldosterone and cortisol (Addison s disease) is life threatening and must be treated with replacement therapy of both hormones. 

Other nonpituitary causes of Cushing s syndrome, however, include a primary tumor of the adrenal cortex secreting excessive amounts of cortisol directly into the bloodstream. This disorder also can result from the release of ACTH from secretory nonendocrine nonpituitary neoplasms ( ectopic ACTH syndrome). Cushing s syndrome is often caused by excessive doses of synthetic GCs used to treat a variety of disorders because of their potent anti-inflammatory effects (iatrogenic Cushing s syndrome). 

A disorder in which there are adenomas or hyperplasia occuring simultaneously in the pituitary, adrenals, pancreas, parathyroids or in any combination of these glands. The symptoms therefore include hyperparathyroidism, acromegaly, Cushing s syndrome, gastric ulceration (if the pancreatic cells produce... 

An abnormal, humplike deposit of fat under the skin of the upper back, which is seen in people who have chronic oversecretion at certain adrenal cortical hormones. The medical name for this disorder is Cushing s Syndrome. 

Cushing s syndrome— This disorder is characterized by oversecretion of adrenal cortical hormones which cause the breakdown and loss of protein from the bones and muscles. Potassium is lost along with muscle protein, and the E)one minerals—mainly calcium and phosphorus—are lost when the protein structure of bone breaks down. People with Cushing s syndrome often have an accumulation of salt and water in their tissues, a condition which gives rise to a... 

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