Endocrine Abstracts

Introduction: The occurrence of Cushing’s syndrome in individuals with chronic renal failure is notably rare. It represents a challenging diagnosis in the context of pre-existing chronic kidney disease due to commonly associated alterations in the hypothalamic–pituitary–adrenal axis function. Consequently, the interpretation of standard tests used to detect hypercortisolism can be peculiarly difficult and reveal concrete particularities in comparison to patients with normal renal function. We here present the case of a chronic hemodialysis patient who was diagnosed with Cushing syndrome disclosed by an adrenal incidentaloma.

Case presentation: In December 2021, a 67-year-old female was admitted to our department for exploration of a 23 mm left-sided adrenal nodule incidentally detected on a computed tomography (CT) performed about 6 months ago for suspicion of an arteriovenous fistula stenosis. Indeed, the patient started hemodialysis 3 times a week since 2014 for end-stage renal disease caused by tubulointerstitial nephritis. In addition, she underwent subtotal parathyroidectomy associated to right loboisthmectomy for tertiary hyperparathyroidism and multinodular goiter in 2015. Clinically, she didn’t have hypercortisolism features except slender lower limbs and a recently diagnosed hypertension. Her body mass index was 28.75 kg/m². Biologically, she had hypertriglyceridemia and glucose intolerance. Subsequent endocrinological testing revealed negative plasma fractionated metanephrines and resistance to suppression of low dose (1 mg), 4 mg and high dose (8 mg) of dexamethasone: the early morning cortisol level was respectively 7.1 μg/dl, 2.6 μg/dl and 2.3 μg/dl. The plasma ACTH level performed twicely was 55 pg/ml and 31 pg/ml. It led to the practice of a brain MRI that was normal. A latterly conducted CT scan detected a left adrenal adenoma with a diameter of 31 mm, spontaneous density of 20 UH, relative washout of 49% and absolute wash out of 64%. The patient didn’t have obstructive sleep apnea. Based on these findings, Cushing’s syndrome secondary to a left adrenal tumor was diagnosed and the patient was presented for left adrenalectomy.

Conclusion: This is the first documented report outlining the coexistence of Cushing syndrome and tertiary hyperparathyroidism in an individual with end stage renal disease and the fourth known case of Cushing disease occurring in a long-term hemodialysis patient. This observation emphasizes the cortisol dynamics alterations broadly associated with renal failure. These pituitary adrenocortical function disturbances are mainly characterized by increased cortisol levels, heightened plasma ACTH levels and resistance to low dose dexamethasone suppression testing highlighting thereby the delicate diagnosis of Cushing disease in this context.