Hormonal Metyrapone

Other tests that can help determine the etiology include the high-dose dexamethasone suppression test, plasma ACTH test, metyrapone stimulation test, corticotropin-releasing hormone stimulation test or inferior petrosal sinus sampling. 

Metyrapone inhibits 11-hydroxylase activity, resulting in inhibition of cortisol synthesis. Initially, patients can demonstrate an increase in plasma ACTH concentrations because of a sudden drop in cortisol. This can cause an increase in androgenic and mineralocorticoid hormones resulting in hypertension, acne, and hirsutism. Nausea, vomiting, vertigo, headache, dizziness, abdominal discomfort, and allergic rash have been reported after oral administration. 

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

Mitchell CE, Longwell BB. 1970. The effects of adrenocorticotrophin hormone and metyrapone on the excretion of urinary steroids by beagle dogs burdened with strontium-90. Radiat Res 41 78-88. 

A number of possible solutions have been proposed to solve the problem, like the use of media supplemented with certain hormones (77), nicotinamide, or metyrapone, or media free of cystine and cysteine, but supplemented with aminolaevulinic acid (77). However, the application of such media has been a limited success since the apparently stable levels of cytochrome P-450 were accompanied by a selective change in the pattern of the different isoenzymes. A more promising approach appears to be the long-term cocultivation of hepatocytes with a rat epithelial cell-line, resulting in steady state levels of cytochrome P-450 after an initial decline (6, 18), However, the results of a recent study by Rogiers et al. (19), indicate that this technique does not offer a complete solution for the selective shift in the cytochrome P-450 isoenzyme patterns. 

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. 

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Cushing s syndrome will be unreliable in patients taking cyproheptadine and phenjdoin, and therefore these should be withdrawn prior to the test.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. ... 

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