Experience with a rapid oral metyrapone test and the plasma ACTH content in determining the cause of Cushing's syndrome

A comparison of the overnight and the standard metyrapone test for the differential diagnosis of adrenocorticotrophin‐dependent Cushing’s syndrome

“…The plasma 11-deoxycortisol response to the overnight metyrapone test was expressed either as the stimulated value on day 2, or as the ratio of stimulated to baseline (day 2/ day 1) as previously described (Sparks et al, 1969;Spiger et al, 1975;Tucci, 1975;Snow et al, 1992;Avgerinos et al, 1994). For consistency the degree of plasma cortisol suppression following overnight metyrapone was also expressed as the ratio of the post-metyrapone (suppressed) value to baseline (day 2/day 1).…”

“…However, these tests had the disadvantages of complicated drug regimens and timed urine collections. In an effort to avoid these disadvantages, abbreviated, overnight versions of both the dexamethasone and metyrapone tests were introduced in order to shorten their duration, simplify the drug regimen, and rely on plasma rather than urine measurements (Meikle et al, 1969;Sparks et al, 1969;Spiger et al, 1975;Tucci, 1975;Nishida et al, 1984;Tyrrell et al, 1986;Snow et al, 1992;Dichek et al, 1994).…”

“…Experience with the overnight metyrapone test is limited. Most of the existing literature addresses its use for differentiating pituitary from adrenal (Meikle et al, 1969;Sparks et al, 1969;Spiger et al, 1975;Tucci, 1975) rather than from ectopic ACTH-producing causes of Cushing's syndrome (Snow et al, 1992). Additionally, none of the previous studies have determined criteria for the diagnosis of Cushing's disease which have 100% specificity in excluding patients with ectopic ACTH syndrome.…”