Cushing Adrenal hyperplasia

ACTH-dependent Cushing s syndrome is usually caused by overproduction of ACTH by the pituitary gland, causing adrenal hyperplasia (Cushing s disease). Pituitary adenomas account for about 80% of these cases. Ectopic ACTH-secreting tumors and nonneoplastic corticotropin hypersecretion are responsible for the remaining 20% of cases. 

After metyrapone administration, a patient with a disease of pituitary origin cannot achieve a compensatory increase in the urinary excretion of 17-hydroxycorti-costeroids or 11-deoxysteroids. Moreover, if pituitary corticotrophin is suppressed by an autonomously secreting adrenal carcinoma, there will be no increase in response to metyrapone. On the other hand, if pituitary corticotrophin secretion is maintained, as occurs in adrenal hyperplasia, the inhibition of corticoid synthesis produced by metyrapone will stimulate corticotrophin secretion and the release of metabohtes of precursor urinary steroids, which can be measured as 17-hydroxycortico-steroids. Metyrapone is now used less frequently in the differential diagnosis of Cushing s syndrome because of the ability to measure plasma corticotrophin directly. 

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. 

Hydrocortisone is also u.scd during postoperative recovery alter surgery For Cushing s syndrome—exce.ssive adrenal. secretion oF glucocorticoids. Cushing s syndrome can be caused by bilateral adrenal hyperplasia or adrenal tumors and is treated by surgical removal oF the tumors or re.section oF hyperpla.stic adrenal gland(s). 

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

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... 

This patient presents with many of the classic findings of Cushing syndrome. Adrenal hyperplasia can be caused by excessive stimulation from ACTH (pituitary or ectopic production) or from a primary adrenal problem such as adenomas/ carcinomas. In addition to above symptoms, patients with Cushing syndrome are also at risk for osteoporosis and diabetes mellitus (DM). The diagnosis is confirmed with elevated cortisol levels after a dexamethasone suppression test. Treatment depends on the underlying etiology and is often surgical. 

This may not nece.ssarily be accompanied by cortisol excess, and signs of Cushing s syndrome may be absent. Patients with congenital adrenal hyperplasia (p. 87) may also present with signs of increased androgen production. 

The mechanism of action of mitotane has not been elucidated, but its relatively selective attack on adrenocortical cells, normal or neoplastic, is well established. Thus, administration of the drng causes a rapid reduction in the levels of adrenocorticosteroids and their metabolites in blood and nrine, a response that is useful both in guiding dosage and in following the course of hyperadrenocorticism (Cushing s syndrome) resulting from an adrenal tumor or adrenal hyperplasia. Damage to the Uver, kidneys, or bone marrow has not been encountered. 

It is sometimes possible to differentiate Cushing s syndrome resulting from adrenal tumor and that due to adrenal hyperplasia. ACTH injection in patients with Cushing s syndrome resulting from hyperplasia increases cortisone levels, but ACTH is without effect in patients with Cushing s syndrome resulting from adrenal tumors. 

Increases are found in pituitary-dependent Cushing s syndrome. Nelson s syndrome, Addison s disease, congenital adrenal hyperplasia and ectopic ACTH production from a tumour. 

The metyrapone test causes a rise in urinary 17-oxogenic steroids in many cases of adrenal hyperplasia but not in the other forms of Cushing s syndrome. 

This is a condition which results from a pituitary adenoma, occuring after total adrenalectomy for Cushing s disease, due to bilateral adrenal hyperplasia. ACTH and MSH may be secreted in response to increased secretion of CRF by the hypothalamus and this results in skin pigmentation. The increased secretion of CRF may be an attempt to maintain the high levels of cortisol that existed before the operation. 

Low values are found in adrenal hypofunction while high values are found in Cushing s syndrome and congenital adrenal hyperplasia. 

ACTH-independent Cushing s syndrome shows increased cortisol, but the ACTH is not elevated but rather decreased due to negative feedback. It can be caused by exogenous administration of glucocorticoids or by adrenal adenoma, carcinoma or nodular hyperplasia. 

Cortisol. Cortisol, secreted by the adrenal cortex in response to adrenocorticotropic hormone (ACTH), stimulates gluconeogenesis and increases the breakdown of protein and fat. Patients with Cushing s syndrome have increased cortisol owing to a tumor or hyperplasia of the adrenal cortex and may become hyperglycemic. In contrast, people with Addisons disease have adrenocortical insufficiency because of destruction or atrophy of the adrenal cortex and may exhibit hypoglycemia. ... 

The remaining 18% of Cushing s syndrome cases are ACTH-independent and are almost equally divided between adrenal adenomas and adrenal carcinomas, with rare cases caused by micronodular or macronodular hyperplasia." The majority of adrenal cortex tumors are benign adenomas. Adrenal carcinoma is found more often in children than in adults with 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... 

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