ESPE Abstracts

Background: Bilateral inferior petrosal sinus sampling (IPSS) is the gold standard for determining the source of hypercortisolism in ACTH-dependent Cushing's syndrome. Traditionally, IPSS is performed with CRH stimulation. Since CRH has been unavailable recently, intravenous desmopressin administration may be preferred during IPSS.

Case Report: A 13-year-old boy presented with a weight gain of 10 kg and a decreased height velocity. His height, weight and BMI were 143 cm (-2.68 SDS), 53.8 kg (-0.14 SDS), and 25.9 kg/m² (1.46 SDS), respectively. Physical examination revealed a moon face, plethora, abdominal striae and buffalo hump. The basal cortisol level was high (33.7 µg/dl). Midnight salivary cortisol and 24-hour urine cortisol level was high (766 µg/day). The dexamethasone suppression test (DMS) (single dose, 1 mg, PO) did not suppress cortisol levels. The basal ACTH level was 54.3 pg/mL. Ultrasonography showed a natural appearance of the surrenal glands. After two days of DMS (2 mg/day), suppression of the cortisol level was inadequate (15.6 µg/dl). After a modified high-dose DMS test (8 mg/day, single dose), the decrease in cortisol level was less than 50%. A pituitary MRI revealed no significant pathology. Intravenous desmopressin-induced IPSS showed significantly elevated ACTH in samples obtained from the right pituitary (Table-1:), and a diagnosis of Cushing's disease was made. Fluid restriction was performed to prevent clinical hyponatremia until diuresis was observed. There was no decrease in serum cortisol levels after the excision of pituitary adenoma. Ketoconazole treatment was started, and a second operation was planned. In the sixth week of ketoconazole treatment, liver function tests deteriorated, and the drug was discontinued. The liver function test results improved one week later. Serum cortisol levels decreased to the normal range after the second operation for adenoma excision. The last evaluation was performed 6 months after the operation, and the patient's hypercortisolemia findings improved.

Conclusion: IPSS should be performed when imaging results are inconclusive in cases of ACTH-induced hypercortisolemia. When CRH is not available for IPSS, desmopressin seems to be safe.