Epidemiology and follow-up of Cushing's disease

Little is known on the epidemiology of Gushing's disease (CD) as relevant d ata on such a rare disease can only be obtained from large-scale studies. W e addressed this topic analyzing the data obtained in the Italian multicent er study which comprised nearly 300 patients with CD. The number of newly d iagnosed patients with CD increased markedly in the second decade of the st udy (from 7.4 +/- 0.71 pts/year prior to 1987 to 26.4 +/- 4.12 after 1987) probably reflecting the heightened awareness of the disease and the increas ed availability of diagnostic tools. Urinary free cortisol (UFC) levels wer e significantly higher in men than in women and were inversely correlated w ith the time interval between appearance of symptoms and diagnosis. Recogni tion of CD among patients presenting with common diseases such as obesity, diabetes and hypertension requires highly sensitive screening tests (e.g. U FC, midnight cortisol in saliva, overnight dexamethasone suppression test) which however may yield false positive results. In doubt, second line testi ng using dex-CRH or desmopressin may distinguish between CD and pseudoCushi ng. The different prevalence of CD and ectopic ACTH secretion (ES) undermin es the diagnostic accuracy of tests used for the differential diagnosis of ACTH-dependent Gushing's syndrome (ie CRH, high dose dexamethasone, IPSS). Tests aimed at identifying ES rather than CD are needed to overcome this bi as. Transsphenoidal surgery was the preferred choice of treatment for patie nts with CD, resulting in remission in 70 % operated patients with a 15 % r elapse rate over 10 years follow up. Definition of remission after surgery and parametres predictive of relapse, however, vary according to studies an d long-term follow-up is required to establish their validity. Most clinica l manifestations of hypercortisolism disappeared after remission although s ome long-lasting effects on the cardiovascular system had been observed. Fi nally, according to recent reports, mortality rates for patients cured of C D appear comparable to those of the general population.