Value of assessing adrenocorticotropic hormone (ACTH) levels in differential diagnosis of hypercorticism

Diagnosis and differential diagnosis of Cushing's syndrome remains a challenge in clinical endocrinology. The aim of this study was to establish the value of assessing adrenocorticotropic hormone (ACTH) levels in differential diagnosis of hypercorticism using receiver operating characteristic (ROC) curve. We have evaluated 114 patients with Cushing's syndrome testing the value of pathohistological examination and postoperative testing. The control group consisted of 53 obese healthy persons. ACTH level was determined using a commercial RIA (CIS, France). ACTH secreting pituitary adenoma was found in 56.14% examinees, ectopic secretion in 6.14%, cortisol secreting adrenal adenoma in 37.57%, and adrenal carcinoma in 6.14% of all patients with Cushing's syndrome. Basal ACTH level for pituitary adenoma was 107.29 +/- 75.69 pg/mL; for ectopic secretion 181.63 +/- 149.84 pg/mL; for adrenal adenoma 4.22 +/- 2.32 pg/mL; for adrenal carcinoma 5.50 +/- 7.72 pg/mL; and 34.76 = 10.07 pg/mL in control group. Testing the value of assessing ACTH the area under ROC curve was 0.9965 +/- 0.0071. Test sensitivity was 99.89% and test specificity was 97%. For ACTH cut-off level of 8 pg/mL, test sensitivity was 88.50%, with specificity of 99%. For ACTH cut-off level of 22 pg/mL, test sensitivity was 99.30%, with specificity of 98%. Our intermediate zone from 8 to 22 pg/mL confirms that assessment of ACTH level is a reliable tool in differential diagnosis of Cushing's syndrome.