Cushing's syndrome

Definition

This is the collection of symptoms caused by high cortisol levels.

Cushing's disease is a specific cause of this (a pituitary tumour). Don't get the two mixed up.

Epidemiology

Usually, it's the result of long-term steroid use. Less commonly, it's one of the other causes detailed below.

Pathophysiology

Too much glucocorticoid. This can be: iatrogenic - long-term steroid therapy; or it can be a disease process:

• pituitary (Cushing's disease) - a tumour in the pituitary gland. Increased ACTH production
• adrenal - tumour or hyperplasia of the adrenal gland
• paraneoplastic - tumours elsewhere in the body, like small cell lung cancer which produce ACTH through an unknown aetiology

Risk Factors

The main one is long-term steroid treatment. Make you sure you watch out for these symptoms in patients who have been on steroids for a long time.

Clinical Features

See steroid side effects for an amusing picture. They like asking this one in exams. This is a good mnemonic - CUSHINGOID

• Cataracts
• Ulcers
• Skin: striae, thinning, bruising
• Hypertension/ Hirsutism/ Hyperglycemia
• Infections
• Necrosis, avascular necrosis of the femoral head
• Glycosuria
• Osteoporosis, obesity
• Immunosuppression
• Diabetes

Others include MOOOOOONFACE & buffalo hump. (MedRevise's personal favourites. Bitemproal hemianopia would suggest Cushing's disease

Investigations

• 9am cortisol - cortisol fluctuates throughout the day so it has to be taken at 9am
• More accurate are:
  • Dexamethasone suppression test
  • 24 hour urinary cortisol

Management

Depends very much on the cause. In iatrogenic - stop the steroids. If it's tumour - cut it out depending on where it is.