Metabolic complications of endogenous Cushing: patient selection for screening

Aims: this study evaluates the most common associations of symptoms and complications in patients with Cushing’s syndrome (CS) in order to choose a potential population to be screened for CS and estimates the diagnostic accuracy of first line screening tests (cortisol, ACTH) to differentiate ACTH-ectopic CS from Cushing’s disease. Materials and Methods: The clinical data of 259 patients with proven CS during 2001–2011 was analyzed. The clinical presentations of 197 patients (159 Cushing’s disease, 28 ACTH-ectopic CS and 10 cases of benign cortisol-secreting adrenal adenoma) were compared according to the cause of hypercortisolism. ROC-analysis was performed to estimate the diagnostic accuracy of the first line tests (cortisol, ACTH) to suggest ACTH-ectopic CS. A threshold for the test with the highest area under the curves was chosen based on the maximum sum of the sensitivity and specificity. Results: The most frequent complaints were related to fatigue, muscle weakness, weight gain and changes in appearance (facial plethora and fullness, striae). Among the complications of CS the most frequent were being overweight or obese (71%), hypertension (63%), dislipoproteinemia (41%), low traumatic fractures (43%) and steroid-induced diabetes (31%). In women, 16% were older than 50, in those who were younger amenorrhea was registered in 43%. The patients with ACTH-ectopic CS had higher rate of low traumatic fractures (p=0.04), increased serum late-night cortisol, 24 hours urinary free cortisol, morning and evening ACTH and lower levels of potassium (p0.01 for all parameters). Plasma late-night ACTH measurements showed the highest AUC (0,811 (95% CI 0,712–0,909)) to differentiate ACTH-ectopic CS from Cushing’s disease. A cut off value of 108.9 pg/ml for late-night ACTH yielded a sensitivity of 60,7% and a specificity of 79%. Conclusions: patients with a coexistence of obesity, muscle weakness, fatigue, some components of metabolic syndrome and especially low traumatic fractures should be screened for CS. High plasma late night ACTH values in patients with proven CS value suggest ACTH-ectopic syndrome.