ABSTRACT
ObjectiveTo evaluate the value of inferior petrosal sinus sampling (IPSS) in the diagnosis of adreno-corticotropic hormone ( ACTH ) dependent Cushing syndrome ( CS ) with unknown origin. MethodsIPSS was carried out for the diagnosis of 16 cases with ACTH dependent CS who had not been identified after a series of dexamethasone suppression tests and radiological examinations. The ratio of inferior petrosal sinus/peripheral ACTH was assayed.The sensitivity and specificity of diagnosis of the Cushing disease were estimated. ResultsThe inferior petrosal sinus/peripheral ACTH ratio was over 2. 0 in 13 cases. Twelve cases underwent surgery with pathological diagnosis of pituitary ACTH adenoma, 1 patient relieved after γ knife treatment. The ratio was ＜ 2.0 in 3 cases including 2 pulmonary carcinoid and one pituitary ACTH adenoma. The sensitivity and specify of IPSS for the diagnosis of Cushing disease were 13/14and 2/2 respectively.ConclusionIPSS was a safe technique with high sensitivity, specify and infrequent complications in the diagnosis of ACTH dependent Cushing disease.It had great clinical value in the differential diagnosis of ACTH dependent Cushing disease with unknown origin.