MISDIAGNOSIS OF CUSHINGS-SYNDROME IN A PATIENT RECEIVING RIFAMPICIN THERAPY FOR TUBERCULOSIS

We hereby describe a patient in whom chronic rifampicin treatment led to a misdiagnosis of Gushing's syndrome. He had long-standing insulin- dependent diabetes mellitus and active tuberculosis resistant to conve ntional treatment. The course was complicated by muscle weakness, lowe r limb atrophy, unstable glycemic control and hypokalemia. Ectopic Gus hing's syndrome was suspected on the basis of high urinary free cortis ol excretion (UFG) with a blunted circadian profile of serum cortisol and measurable plasma AGTH concentrations. Dynamic endocrine tests and imaging studies were compatible with occult ectopic AGTH syndrome. Af ter substitution of rifampicin UFG excretion returned to normal within two weeks, as well as the 24-h cortisol profile and dynamic tests. Th e present case provides a practical example of the possibility to inco rrectly suspecting Gushing's syndrome in patients treated with rifampi cin, as previously envisaged by pharmacological studies.