Endocrine Abstracts

Background: The case is a 64 year old patient referred by the GP who noticed she looked ‘cushingoid’. She gave an approximately 4 year history of a change in facial complexion, central weight gain, unsteadiness and poor wound healing. There was a history of depression, essential hypertension and previous back surgery. On examination she was plethoric, had pedal oedema, thin skin and central obesity (BMI 32).

Investigations: Initial overnight dexamethasone suppression test (DST) did not suppress cortisol (500nmol/l). Two 24 hour urine free cortisol (24UFC) tests were raised at 439 and 346nmol/24hours (55-284), confirming the diagnosis of Cushing’s syndrome. Pituitary profile showed normal IGF-1, prolactin, post-menopausal gonadotrophins and hypothyroidism. Repeat low dose DST gave a similarly high cortisol level of 527nmol/l. High dose DST again failed to fully suppress, with cortisol 118nmol/land ACTH 34ng/l, suggesting either a pituitary or an ectopic source. Corticotrophin releasing hormone test was suggestive of pituitary rather than ectopic disease, with ACTH ranging 28 to 47ng/land cortisol ranging 365 to 698nmol/l. MRI pituitary gland suggested a possible 3mm pituitary adenoma. A plan was made for a methionine PET scan prior to surgery. One year following presentation however, 24UFC was normal at 236nmol/l, and symptoms had improved. A diagnosis of cyclical Cushing’s disease was made. Following biochemical recurrence in 2021, the patient declined the option of either pituitary or adrenal surgery and has opted to ‘watch and wait’. Her preference would be for block and replace with metyrapone if symptoms recur.

Summary: This case highlights the complexities in diagnosing Cushing’s disease and is a reminder of the possibility of cyclical Cushing’s, which further increases the difficulty in diagnosis and management. Daily, sequential assessment of urine or salivary cortisol has been suggested to aid the diagnosis however this can be impractical for some patients. Locating the source of cortisol excess needs to be performed when the patient is symptomatic. Treatment options remain the same as for non-cyclical Cushing’s disease once the source is located.