THE VALUE OF INFERIOR PETROSAL SINUS SAMPLING IN DIAGNOSIS AND TREATMENT OF CUSHINGS-DISEASE

OBJECTIVE While microsurgical selective adenomectomy is the best metho d available at present for the treatment of Cushing's disease, its suc cess depends to a large degree on precise preoperative intrapituitary microadenoma localization. This study compares the results of intrapit uitary adenoma localization obtained with inferior petrosal sampling, computerized tomography and magnetic resonance imaging with the adenom a localization as found at surgery. DESIGN The results of inferior pet rosal sampling for intrapituitary localization of ACTH-producing pitui tary adenomas were compared in a retrospective study with the results of computerized tomography, magnetic resonance imaging, surgical and p athological findings. Special attention was paid to the intersinus ACT H relation. PATIENTS Thirty-eight patients (33 women and 5 men) of 11- 68 years of age suffering from pituitary-dependent Cushing's disease w ere studied. Patients with ectopic ACTH-secreting tumours and recurren t pituitary adenomas were excluded. MEASUREMENTS Blood samples were ob tained simultaneously from both inferior petrosal sinuses and a periph eral vein before and 5, 10, 15 and 20 minutes after stimulation with 6 0 mu g/m(2) human corticotrophin-releasing hormone (hCRH). RESULTS Of the adenomas in our series, 42% had a diameter of 3 mm or less. Only 6 of 20 adenomas examined by computerized tomography and 11 of 29 exami ned by magnetic resonance imaging were identified correctly. inferior petrosal sinus sampling produced significantly better results, particu larly when combined with a stimulation test with hCRH: for 29 of 38 ad enomas examined, the location was predicted correctly with these techn iques. Analysis of the intersinus adrenocorticotrophin concentration r atio showed that the best right-central-left discrimination was obtain ed with values of 1.3 and 1.4. CONCLUSIONS We conclude that inferior p etrosal sinus ACTH sampling after hCRH stimulation is the best method available for the intrapituitary localization of microadenomas causing Cushing's disease provided that the appropriate technique of blood sa mpling is used meticulously.