Differential diagnosis of Cushing's syndrome

Article Abstract:

This editorial comments on the results of a research article published in the September 26, 1991 issue of The New England Journal of Medicine concerning a diagnostic test for Cushing's disease. This disorder is one of the many that can cause Cushing's syndrome, the hallmark sign of which is an elevated blood level of cortisol, a hormone produced by the adrenal gland. There are essentially two pathways by which cortisol levels may be elevated: a tumor of the pituitary (an adenoma) or elsewhere in the body may produce increased levels of adrenocorticotropin (the pituitary hormone that stimulates the adrenal glands to produce cortisol); or from adrenocorticotropin-independent production of the hormone, usually by an adrenal tumor. When the disorder is the result of a pituitary adenoma, it is called Cushing's disease. The diagnostic test presented in the article involves sampling blood from the inferior petrosal sinus (one of the blood-filled venous cavities in the brain) and comparing adrenocorticotropin levels in these samples with levels in samples of blood from a peripheral vein. Thus, the test shows to what extent the concentration of adrenocorticotropin in blood nearer the pituitary gland is greater than in peripheral blood; ratios above a criterion level indicate a diagnosis of Cushing's disease. The study was carried out on 278 patients, a large number, and its results will certainly change the diagnostic approach to Cushing's syndrome. However, some points are raised concerning the limitations of this test. Patients whom doctors encounter in practice may have different physiologic characteristics than the patients studied, who displayed somewhat unusual forms of the disease. Considerable skill is needed to take blood samples from the inferior petrosal sinus, and a skilled laboratory is required to perform the assays. These conditions may be hard to duplicate. A protocol for diagnosing Cushing's syndrome is presented. The test using petrosal sinus blood is carried out after certain steps have been taken to verify that the syndrome is adrenocorticotropin-dependent; these steps are described. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Adrenocortical hormones, Pituitary gland tumors, Pituitary tumors, editorial

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Adrenomyeloneuropathy presenting as Addison's disease in childhood

Article Abstract:

Addison's disease, failure of the adrenal glands, has various causes. A rare cause of Addison's disease which occurs in children is adrenoleukodystrophy, an inherited condition. Adrenoleukodystrophy usually involves severe progressive dementia (mental confusion) and deterioration of speech, vision, and ability to walk. These neurological manifestations result from inability to metabolize certain fatty acids, which collect in the brain and adrenal glands and cause the disabilities. A milder form of adrenoleukodystrophy which advances more slowly has been identified; this condition is called adrenomyeloneuropathy. Both diseases are inherited from sex-linked genes and both may be found in the same family. Adrenomyeloneuropathy typically begins in adolescence or the early adult years; initial symptoms usually include weakness and lack of coordination in the legs. Occasionally adrenal insufficiency (Addison's disease) may be the first sign of adrenomyeloneuropathy, with neurological symptoms developing years later. Eight male patients who had Addison's disease diagnosed in childhood were examined for early signs of adrenomyeloneuropathy. Five patients did show evidence of adrenomyeloneuropathy from blood tests and magnetic resonance imaging of the brain. Because the disease is sex-linked, the authors conclude that any boy who has Addison's disease should be evaluated for adrenomyeloneuropathy. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Addison's disease, Adrenoleukodystrophy

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Cushing's syndrome

Article Abstract:

Cushing's syndrome occurs when the body produces too much cortisol, which is a hormone produced by the adrenal glands. The most common form of Cushing's syndrome is Cushing's disease, which is characterized by excess secretion of the pituitary hormone corticotropin. Corticotropin stimulates the adrenal glands to produce cortisol. Pituitary tumors are usually responsible for this condition. Cushing's syndrome has characteristic signs and symptoms, including weight gain, a 'moon face' caused by increased facial fat, hypertension, glucose intolerance, muscle weakness, depression and insomnia. Elevated cortisol levels in urine samples are a reliable diagnostic test. The dexamethasone suppression test can also demonstrate the lack of a normal response to hormone feedback at the pituitary level. The best treatment for Cushing's disease is surgical removal of the pituitary tumor. Radiation to the pituitary and removal of most of the gland may be necessary. It may be necessary to remove one or both adrenal glands in patients whose Cushing's syndrome is caused by adrenal tumors.

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