RT Journal
A1 Kapcala LP, Hamilton SM, Meikle A
T1 CUshing's disease with 'normal suppression' due to decreased dexamethasone clearance
JF Archives of Internal Medicine
JO Archives of Internal Medicine
YR 1984
FD March 1
VO 144
IS 3
SP 636
OP 637
DO 10.1001/archinte.1984.00350150250051
UL http://dx.doi.org/10.1001/archinte.1984.00350150250051
AB • Suppression of urinary corticosteroids during low-dose dexamethasone testing (0.5 mg every six hours eight times) has commonly been recognized as a response that excludes the diagnosis of Cushing's syndrome. Although "normal suppression" has been reported previously in Cushing's disease, rarely has an explanation been provided for this aberrant response. We report a case of proven Cushing's disease in which normal suppression was observed with low-dose dexamethasone testing. Further study suggested that this phenomenon, which is not widely recognized, was related to an abnormally decreased clearance of dexamethasone. We therefore suggest that whenever responses to testing appear discordant with the clinical index of suspicion, simultaneous plasma dexamethasone and cortisol levels should be obtained to exclude abnormalities in dexamethasone clearance.(Arch Intern Med 1984;144:636-637)