Cushing's syndrome: symptoms, causes, diagnosis and treatment

Cushing's syndrome is a rare condition caused by having too much of a hormone called cortisol in your body. The NHS says you are more likely to get it if you take high doses of steroid medicines for a long time.

Cortisol is a hormone made by the adrenal glands, two small glands above the kidneys. The Pituitary Foundation says it is vital for life, helping to regulate blood pressure and the immune system, helping balance the effect of insulin to keep blood sugar normal, and helping the body respond to stress. Too much cortisol over a long period affects many parts of the body.

Cushing's syndrome is the name for any cause of high cortisol. The Pituitary Foundation explains that if the cause is a growth in the pituitary gland, the correct name is Cushing's disease. The NHS describes the condition as rare, and the Pituitary Foundation gives a quoted incidence of 1 in 200,000 while noting that it is now found more often when specifically looked for.

The NHS says symptoms often come on gradually. They include more body fat on the neck, upper back, chest and tummy while the arms and legs look thin by comparison, a red, round face (the redness may be harder to see on brown or black skin), skin that bruises easily, stretch marks on the tummy, hips, breasts and under the arms, muscle weakness especially at the top of the arms and legs, low sex drive, mood changes such as irritability, anxiety or depression, irregular or absent periods and excessive hair growth.

The Pituitary Foundation adds a fatty hump at the top of the back, acne, darkening of skin pigmentation, thinning and fragile skin, weaker bones, higher blood pressure, diabetes and excess thirst, reduced fertility in men, being more prone to infections, and, in children, growth stopping while weight increases. It points out that many people look back and realise there were clues two or more years before referral. The NHS says Cushing's is rare in children, with obesity and short height the main symptoms.

Many of these symptoms are common in the general population, and most people with weight gain, high blood pressure, diabetes or excess hair do not have Cushing's, as the Pituitary Foundation emphasises. A diagnosis rests on tests rather than appearance.

• Weight gain around the trunk with thinner limbs.

• A rounder, redder face and a fatty hump at the base of the neck.

• Easy bruising, thin skin and wide purple stretch marks.

• Muscle weakness, tiredness and weakened bones.

• High blood pressure, high blood sugar and mood changes.

• Menstrual irregularity, reduced libido and excess hair growth.

The two names are often used as if they were the same, but they are not. The Pituitary Foundation says Cushing's syndrome is the name given to any cause of high cortisol, and that when the cause is a growth in the pituitary gland the correct name is Cushing's disease. The NHS draws the same line.

The type of Cushing's also matters for treatment, which is why the first job after high cortisol is confirmed is to find where it is coming from.

The NHS and the Pituitary Foundation both say that the most common reason is treatment with glucocorticoid steroid medicine, for example prednisolone for asthma, arthritis or colitis. The Pituitary Foundation calls this exogenous Cushing's. If you take steroids and have symptoms, speak to the prescriber before changing anything. The NHS lists gradually reducing the steroid dose as the treatment in this situation.

Spontaneous Cushing's, which comes from within the body, is rare. The Pituitary Foundation says the most common cause of spontaneous Cushing's, around 70% of cases, is a small non-cancerous tumour of the pituitary gland that makes too much ACTH, the hormone that tells the adrenal glands to release cortisol. Other causes are a growth elsewhere in the body that makes ACTH (ectopic ACTH) and a growth in an adrenal gland. The Pituitary Foundation says there are no known environmental triggers and the condition is not hereditary, and that far more women than men have it for reasons not known.

The Pituitary Foundation also describes cyclical Cushing's, in which the cortisol level varies greatly over months or years, which can make diagnosis harder and sometimes requires repeat testing.

The NHS says you should see a GP if you have symptoms, particularly if you are taking steroid medicine. The GP can arrange tests of the amount of cortisol in a sample of blood, urine or saliva, and if cortisol is high you may be referred to an endocrinologist for further tests of the pituitary and adrenal glands, which may include blood tests and scans of the brain and kidneys.

The Pituitary Foundation explains that the first tests establish whether Cushing's is present at all. They may include a dexamethasone tablet, which in people without Cushing's suppresses cortisol production, blood tests, a 24-hour urine collection and late-night saliva tests, and they may need repeating. Only once Cushing's is confirmed are further tests used to find the cause, such as blood samples through the day, a higher dose of dexamethasone, stimulation tests, measuring ACTH in blood from the pituitary gland (inferior petrosal sinus sampling) and MRI or CT scans of the pituitary and adrenal glands. A bone density test may also be used. Treatment with medicines such as metyrapone or ketoconazole may be started in the meantime to lower cortisol.

The NHS says treatment depends on the cause and severity. Options include gradually reducing steroid medicine if that is the cause, medicine to control cortisol production by the adrenal glands, radiotherapy for a pituitary growth, surgery to remove a growth in the pituitary or adrenal glands, and surgery to remove the adrenal glands, after which hormone-replacing medicines are needed for life. After treatment, cortisol is rechecked, and if it is still high, further treatment may be needed.

For Cushing's disease the Pituitary Foundation says surgery is usually needed, often through the nose under general anaesthetic (transsphenoidal surgery) with no external scar. Most people are up and about the next day and home within a few days, with four to six weeks away from work planned, perhaps longer. It lists temporary effects such as avoiding nose-blowing for three weeks or more, numbness of the front teeth and loss of smell for weeks or months, and temporary thirst and passing more urine from arginine vasopressin deficiency, which is treatable with desmopressin.

After successful surgery, the Pituitary Foundation says you may need replacement hydrocortisone or another steroid tablet for some time, because the body's own control systems have been switched off, and that you are likely to feel worse for several weeks and months before you begin to feel better. Hormone tests are repeated after the operation to check success and look for other pituitary hormone deficiencies, which may need replacement. The Pituitary Foundation also publishes sick day rules; ask your team how they apply to you.

The NHS says Cushing's syndrome is rare in children, and that if a child does get it the main symptoms are obesity and being short for their age. The Pituitary Foundation describes growth stopping while weight increases, and says that although it is rare in children, some as young as six have been diagnosed.

Slow growth with weight gain has several explanations, so a GP is the right first contact. A child with these features should be assessed by the GP rather than watched at home.

If untreated, the NHS says Cushing's syndrome can cause heart attack and stroke, high blood pressure, type 2 diabetes, an increased risk of blood clots, weakened bones and kidney stones. This is why investigation of persistent symptoms matters.

With treatment, strength, mood and other symptoms gradually diminish over several months according to the Pituitary Foundation, although recovery after surgery is not immediate. Long-term follow-up with an endocrinologist is usual, because cortisol levels need rechecking and other hormones may need replacing. The NHS and Pituitary Foundation both point to the Pituitary Foundation's helplines and online support group for support.

See a GP if you have symptoms of Cushing's syndrome, especially if you take steroid medicine. The NHS gives this as non-urgent advice, because the symptoms come on gradually.

Urgent help is different and mainly concerns people on replacement steroids, for example after surgery or if the adrenal glands have been removed. The Pituitary Foundation says that if the body does not get enough steroid when it needs more, cortisol can drop dangerously low in what is called an adrenal crisis, which can be life-threatening. Its sick day rules page says to call an ambulance and go to hospital straight away for an adrenal crisis, and to call 111 or 999 if you start to feel worse with an infection.

Do not stop or cut steroid tablets on your own. Speak to the prescriber, who will reduce them gradually if that is the right plan.

On the NHS, the GP arranges first cortisol testing and an endocrinology team carries out the specialised tests. The Pituitary Foundation notes that you may be referred to a hospital very familiar with Cushing's, which can mean travelling beyond your local hospital for some tests or surgery.

A private endocrinologist may speed up the initial tests, but diagnosis relies on repeated, carefully timed hormone tests, so ask which tests are planned and how the results will be interpreted. Pituitary and adrenal surgery is a specialist field, and it is reasonable to ask a surgeon about their experience and to ensure that your NHS records and follow-up remain joined up.