- Julia Kate Prague, specialty registrar 1,
- Stephanie May, general practitioner2,
- Benjamin Cameron Whitelaw, consultant physician1
- 1Endocrinology, King’s College Hospital, London SE5 9RS, UK
- 2Stockwell Group Practice, London SW9, UK
- Correspondence to: B C Whitelaw
- Accepted 1 January 2013
A 45 year old woman was being regularly reviewed in primary and secondary care because of a five year history of type 2 diabetes that had required early insulin treatment; refractory hypertension; and subsequent chronic kidney disease. She had previously described other symptoms, including weight gain, bruising, flushes, and low mood, all of which had been attributed to obesity and menopause. She was not taking any glucocorticoids. After presenting to her local emergency department with a Colles’ fracture after a low impact fall, she was referred to the endocrinology department for suspected Cushing’s syndrome; subsequent investigation confirmed the diagnosis.
What is Cushing’s syndrome?
Cushing’s syndrome describes the clinical consequences of chronic exposure to excess glucocorticoid irrespective of the underlying cause. Endogenous causes of Cushing’s syndrome are rare and include a cortisol-producing adrenal tumour, which may be benign or malignant; excess secretion of adrenocorticotrophic hormone (ACTH) from a pituitary tumour (Cushing’s disease); or an ectopic ACTH-producing tumour (ectopic Cushing’s syndrome). More commonly, prolonged administration of supraphysiological glucocorticoid treatment (including tablets, inhalers, nasal sprays, and skin creams) can also cause the same clinical condition1 2 (also known as exogenous or iatrogenic Cushing’s).
How common is Cushing’s syndrome?
An estimated 1% of the general population use exogenous steroids. Of these, 70% experience some adverse effects and about 10% have overt Cushing’s syndrome1 3
Conversely, endogenous Cushing’s is rare. Analysis of a national register in Denmark reported an annual incidence of two cases per million people4
However, screening studies of high risk populations show a higher prevalence of endogenous Cushing’s syndrome: in patients referred to secondary care for poorly controlled diabetes, prevalence was 0.6% in one prospective multicentre study5 and 0.5% in those referred for resistant hypertension in a single centre retrospective review of 4429 consecutive referrals6
Endogenous Cushing’s is usually (in 70% of cases) a result of …