ESPE Abstracts

Context: Corticotropin-releasing hormone (CRH)-stimulated inferior petrosal sinus sampling (IPSS) has an important role in the differential diagnosis of hypercortisolism of pituitary or ectopic origin as the most accurate procedure in terms of sensitivity and specificity compared with clinical, biochemical and imaging analyses. However, due to the cost and unavailability issues of CRH, desmopressin may be an alternative to CRH during IPSS.

Objective: Use of desmopressin instead of CRH during IPSS in two patients with suspected CD.

Design and Setting: Clinical, laboratory and radiological characteristics of 2 patients and evaluation of the results of IPSS with desmopressin.

Methods: Petrosal sinus sampling was performed because the patients had no visible adenoma on magnetic resonance imaging (MRI) or abdominal imaging and cortisol response compatible with CD on screening tests. ACTH sampling was performed from the peripheral, right and left petrosal sinuses, followed by desmopressin injection. The diagnosis was based on the ratio of petrosal sinus to venous ACTH after the desmopressin test. The diagnosis was confirmed by surgery and pathology.

Results: Patients was admitted to our centre with complaining of increase rate of gaining weight for 6 months (P1), and decrease in the rate of growth in height with weight gain (P2) aged 6 years 9 months and 9 years 10 months, respectively. Screening tests for Cushing's disease and a suppression test with 8 mg dexamethasone were positive for Cushing's disease. However, no adenoma could be detected on MR. In the P1 under general anaesthesia, appropriate serum ACTH samples were obtained at 0 minutes and 10 mg of DDAVP was administered intravenously. Samples were then taken at 1, 3, 5 and 15 minutes. Based on the results, a diagnosis of right lateralised Cushing's disease was made, and the patient was taken to surgery and pathologically diagnosed as an ACTH-secreting pituitary adenoma. In the second patient, samples were taken at -5, -10, 0, 3, 5 and 10 minutes using a similar procedure and the results were evaluated and right lateralisation was demonstrated as in the other patient and Cushing's disease was confirmed after the patient was referred for surgery.

Conclusion: In ACTH-dependent Cushing's disease, desmopressin testing during petrosal sinus sampling is a safe and cost-effective diagnostic procedure. It is therefore a valuable alternative to CRH.