Endocrine Abstracts

Introduction: Cyclic Cushing’s Syndrome is an uncommon disorder characterized by recurrent episodes of elevated cortisol levels, alternating with periods of normal cortisol secretion. These cycles of hypercortisolism can occur at regular or irregular intervals, ranging from days to years between episodes.

Case presentation: A 57-year-old woman evaluated at the Endocrinology Outpatient Clinic because of symptoms of hypercortisolism with 18 months of evolution: unexplained weight gain (15 kilograms), worsening blood pressure control, thin arms and legs, a moon face and proximal muscle weakness. On physical examination, the patient presented a cushingoid facies without facial plethora, cervical fat accumulation and centripetal obesity. Her medical history included hypertension since 2019 with optimal control using two antihypertensive drugs. She underwent laboratory investigation to document the presence of hypercortisolism and was diagnosed with ACTH-dependent hypercortisolism, evidenced by elevated midnight salivary cortisol levels (37.9 nmol/l; n <7.6) and 24-hour urinary free cortisol (UFC) (4485.3 nmol/day; NR: 11.8-485.6), as well as elevated ACTH (137.4 pg/mL; n <60). Pituitary MRI confirmed the presence of a microadenoma with 7mm. Although she was proposed for bilateral inferior petrosal sinus sampling (BIPSS), in the days preceding the procedure, she presented significant improvement of her symptoms. Cortisol levels dropped significantly: 0800 hours serum cortisol of 4.5 ug/dl (NR: 6.2-19.3) measured twice and a 24-hour UFC of 18.7 ug/day (NR: 4.3-176). Subsequent MRI failed to definitely demonstrate pituitary apoplexy and there were no clinical evidence suggesting this diagnosis. The diagnosis of Cyclic Cushing’s Syndrome was assumed to be the most likely and BIPSS was not performed. One month later, she was evaluated for generalized fatigue and there was again evidence of hypercortisolism with elevated midnight salivary cortisol levels (63.0 nmol/l; n <7.6) and a 24-hour UFC of 2540.6 nmol/day (NR: 11.8-485.6), confirming recurrent cortisol secretion in favour of the diagnosis of Cyclic Cushing’s Syndrome. BIPSS is scheduled to be performed later this month, despite the increased probability of Cushing Disease.

Conclusion: Cyclic Cushing’s Syndrome poses a unique challenge in the realm of endocrine disorders. Unlike its more predictable counterpart, this syndrome involves intermittent hormone level fluctuations, complicating both diagnosis and treatment. The diagnosis remains a complex task and demands continuous patient follow-up. This case emphasize the importance of optimizing confirmation of hypercortisolism at the time of BIPSS.