A 28-year-old woman presents with a one-year history of marked weight gain of 18 kg, increasing hirsutism and night sweats. Clinically, hyperandrogenism and Cushing’s syndrome were suspected. A diagnosis of Polycystic ovarian syndrome was made based on Rotterdam criteria and Metformin was initiated. Initial testing for Cushing’s syndrome demonstrated a high 24 h urinary free cortisol (306 nmol/l) with incomplete cortisol suppression on an overnight dexamethasone suppression test (cortisol 60 nmol/l).However, a follow up low dose dexamethasone suppression test (48 h cortisol <28 nmol/l) and repeat overnight dexamethasone suppression test (Cortisol 44 nmol/l) were normal, casting doubt on the diagnosis of Cushing’s syndrome. Clinical suspicion for Cushing’s syndrome remained high as she continued to gain weight and experienced cyclic symptoms of rapid weight gain, easy bruising and emotional lability, and for this reason, further investigations were carried out. Serial midnight salivary cortisol and cortisone measurements were elevated ranging 3.5–7.4 nmol/l (normal <2.6 nmol/l) and ranging 12.8–31.3 (normal <18 nmol/l) respectively. Later a follow-up overnight dexamethasone suppression test showed no suppressibility of cortisol (84 nmol/l). Cyclic Cushing’s syndrome was now suspected. A pituitary MRI showed a 3 mm right sided microadenoma and inferior petrosal sinus sampling clearly excluded ectopicACTHsecretion. Endoscopic transsphenoidal pituitary tumour resection was scheduled and performed using Brainlab image guidance. A day 4 cortisol (<28 nmol/l) was consistent with surgical remission and hydrocortisone was started. Histology of the pituitary lesion showed clear features of a Corticotroph adenoma. A follow up six-week insulin tolerance test confirmed secondary hypoadrenalism (peak cortisol 112 nmol/l).Post-operatively patient symptomology has now resolved with a reduction of Cushingoid features over time. She is having periods every 28 days (previously 26 days) and has plans for pregnancy in the coming year. Cyclic Cushing’s syndrome is a rare, difficult to diagnose, form of Cushing’s syndrome. It is often overlooked and is characterised by a cyclic pattern of normal cortisol interspersed with episodes of hypercortisolaemia. Intercycles periods can range from days to months. With the advent of the obesity epidemic it is becoming increasingly important for clinicians to remain vigilant when clinical suspicion of Cushing’s syndrome is high despite conflicting Cushing syndrome screening results. We recommend the use of various cortisol screening tests in a temporal fashion and make use of a symptom diary whenever Cyclic Cushing’s syndrome is suspected as the Cortisol Wave can be easily missed!
05 Sep 2020 - 09 Sep 2020