What initial investigations should I perform to confirm a diagnosis of Cushing's syndrome in a patient with suggestive symptoms?

Initial investigations for suspected Cushing's syndrome involve performing screening tests ¹. If a patient has at least one abnormal screening test result, or if clinical suspicion of Cushing's syndrome remains despite normal screening test results, they should be referred to endocrinology for further investigation and management ¹. The urgency of this referral depends on the specific clinical situation ¹. Investigations and management in secondary care vary based on the underlying cause ¹. Urgent admission should be arranged if there are any symptoms or signs of life-threatening complications, such as sepsis, pulmonary embolism, myocardial infarction, or stroke ¹. Referral under a suspected cancer pathway (for an appointment within 2 weeks) is necessary if there is any suspicion of a malignant underlying cause of Cushing's syndrome ¹. Children or pregnant women suspected of having Cushing's syndrome should be discussed with or urgently referred to paediatric endocrinology or obstetrics, respectively ¹.