Endocrine Abstracts

Background: Although the most common causes of hypokalemia are diuretic use and gastrointestinal losses, elevated cortisol levels can also cause hypokalemia through its effects on the renin-angiotensin-aldosterone system.

Case report: A 56-year-old woman with a history of diabetes mellitus and hypertension, presented to our emergency department with fast progressing generalized weakness, abdominal discomfort and diarrhea. Digestive tract diseases were ruled out. Physical examination revealed a female with hyperpigmented face, buffalo neck, and thin upper and lower extremities. She had neither abdominal striae nor moon face. Electrocardiogram (ECG) showed a regular sinus rhythm with diffuse flat T-waves. Laboratory tests indicated hyperglycemia, metabolic alkalosis, thrombocytopenia (15,000 elt/mm³) and persistent severe hypokalemia (up to 1.9 mmol/l) despite the intravenous infusion of potassium. Markedly elevated plasma ACTH (1782 ng/ml (VN: 10–48)) and cortisol (1340 nmol/l (VN: 200–600)) levels were observed. No suppression of serum cortisol level with high-dose dexamethasone test was found, confirming ectopic ACTH dependent cushing’s syndrome (ECS). Chest X ray was normal. Computed tomographic (CT) scan detected a large mass of 53*27*25 mm at the corporo-caudal portion of the pancreas with multiple hepatic and peritoneal metastases. The severe metabolic alkalosis secondary to glucocorticoid-induced excessive mineralocorticoid activity was treated with potassium supplements and spironolactone. A CT-guided biopsy of the mass to determine her pathological type could not be done because of the severe thrombocytopenia. The bone marrow aspiration had not shown metastases. Further investigations havenot been done because of the rapidly fatal evolution.

Conclusion: This case illustrated a rare cause of Cushing’s syndrome, ectopic ACTH secretion. A quarter of these cases remain occult without determining the source of the ectopic secretion. They generally present with electrolyte disturbances rather than typical cushingoid feature because the hypercortisolism is an acute phenomenon and the patients generally do not survive long enough until morphologic changes occur.