Metyrapone test

The unstimulated serum cortisol and rapid ACTH stimulation tests are useful in the diagnosis of adrenal crisis (Table 42-2). The insulin tolerance test is contraindicated owing to preexisting hypoglycemia. The metyrapone test is also contraindicated because metyrapone inhibits cortisol production. 

Other tests include the insulin hypoglycemia test, the metyrapone test, and the corticotrophin-releasing hormone stimulation test. 

Two further communications [31,32] reported that prednisolone stearoylglycollate, in substantial doses, was the least potent anti-inflammatory steroid (among the representative series studied) with respect to pituitary-adrenal inhibition. The order of increasing suppressive potency in this test was prednisolone stearoylglycollate, prednisolone, triamcinolone, dexamethasone, betamethasone. Techniques used in the comparative evaluations included the metyrapone test and gas-liquid chromatography. 

Impaired glucose tolerance decreased pregnanediol excretion reduced response to metyrapone test reduced serum folate concentration. 

The metyrapone test may be used diagnostically to evaluate the proper functioning of the anterior pituitary gland. When administered orally, metyrapone has the following effects ... 

Both long-term and short-term progestational therapy can suppress pituitary ACTH production to some extent, as studied with the metyrapone test. Medroxyprogesterone and chlormadinone suppress the... 

In practice the measurement of serum or plasma 11-deoxycortisol (compound S) is used to document an Up-hydroxylase deficiency or as part of the metyrapone stimulation test. Because metyrapone inhibits the lip-hydroxylase enzyme, a fortyfold to eightyfold increase in plasma 11-deoxycortisol is observed in patients with normal pituitary-adrenal reserve. Consequently, immunoassay methods for 11-deoxycortisol in metyrapone test specimens need not be higlily sensitive. In these patients, a corresponding drop in serum cortisol is observed. A failure to demonstrate an increase in 11-deoxycortisol to at least 4 U,g/dL suggests either an inadequate pituitary ACTH reserve or primary adrenal failure. 

Avgerinos PC, Nieman LK, Oldfield EH, Cutler GB Jr. A comparison of the overnight and the standard metyrapone test for the differential diagnosis of adrenocorticotrophin-dependent Cushing s syndrome. Chn Endocrinol 1996 45 483 91. 

The metyrapone test may be used diagnostically to evaluate the proper functioning of the anterior pituitary gland. When administered orally, metyrapone inhibits the activity of 11-beta-hydroxylase, which is necessary for the synthesis of cortisol, corticosterone, and aldosterone, promotes the release of corticotropin, which in turn increases production of the precursors (11-deoxycortisol and 11-deoxycorticosterone), and enhances the appearance of 17-hydroxycorticoster-oids and 17-ketogenic steroids. 

Carson, S.W. Jusko, W.J. Simultaneous analysis of cortexolone and cortisol by high-performance liquid chromatography for use in the metyrapone test. J.Chromatogr., 1984, 306, 345-350 Molokhia, A.M. El-Hoofy, S. Al-Rahman, S. A HPLC method for the determination of butaperazine in solutions, tablets, plasma and bile. J.Liq.Chromatogr., 1984, 7, 1643-1649 [butaperazine solutions tablets plasma bile hydrocortisone is IS fluorescence detection]... 

The results of the metyrapone test for Cnshing s syndrome are unreliable in patients taking cyproheptadine or phenytoin. The manufacturer also states that barbiturates, antidepressants, some hormones, and antipsychotics may infinence the results of the test. 

Pretreatment with cyproheptadine 4 mg every 6 hours, 2 days before and throughout a standard metyrapone test (750 mg every 4 hours for 6 doses), redueed the metyrapone-induced urinary 17-hydroxycorticosteroid response in 9 healthy subj ects by 32%, and also reduced the serum 11 -deox-... 

The results of metyrapone tests for Cushing s syndrome will be unreliable in patients taking cyproheptadine and phenjdoin, and therefore these should be withdrawn prior to the test. The manufacturer also states that barbiturates, antidepressants (they name amitriptyline) and antipsychotics (they name chlorpromazine), hormones that affect the hypothala-mo-pituitary axis, and antithyroid drugs may influenee the results of the test. They recommend that, if any of these drugs cannot be withdrawn prior to the test, the necessity of earrying out the metyrapone test should be reviewed. ... 

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. 

See also congenital adrenal hyperplasia, metyrapone test... 

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