Cushing's syndrome: what it is, symptoms, causes and treatment

Cortisol is a hormone made by the adrenal glands, two small glands just above the kidneys. The Pituitary Foundation says it is vital for life, and helps regulate blood pressure and the immune system, balance the effect of insulin to keep blood sugar normal, and help the body respond to stress. Cushing's syndrome develops when the body has too much of it.

The NHS calls Cushing's syndrome rare. The Pituitary Foundation explains that the name Cushing's syndrome applies to any cause of high cortisol, while Cushing's disease is the correct name when the cause is a growth in the pituitary gland. Cyclical Cushing's is a form where cortisol levels vary greatly over months or years, which can delay diagnosis.

The NHS says symptoms often come on gradually. The Pituitary Foundation adds that they are wide ranging, usually several are present at once, and many patients realise in hindsight that there were clues two or more years before they were referred to an endocrinologist.

• More body fat on your neck, upper back, chest and tummy, while your arms and legs may look thin compared with the rest of your body.

• A red, round face (harder to see on brown or black skin).

• Skin that bruises easily, and stretch marks on your tummy, hips, breasts and under your arms.

• Muscle weakness, particularly at the top of your arms and legs.

• Low sex drive.

• Mood changes such as feeling irritable, anxious or depressed.

• Irregular periods or periods stopping completely.

• Excessive hair growth (hirsutism).

• The Pituitary Foundation also lists a fatty hump at the top of the back, acne, higher blood pressure, diabetes, weaker bones, thin fragile skin and being more prone to infections.

The NHS says the most common cause is taking high doses of steroid medicine such as hydrocortisone or prednisolone for a long time. The Pituitary Foundation calls this exogenous Cushing's, for example from prednisolone taken for asthma, arthritis or colitis. It also describes spontaneous Cushing's, which comes from within the body and is rare.

The table summarises the causes described by the NHS and the Pituitary Foundation.

The NHS says that if a GP thinks you might have Cushing's syndrome, they can arrange for the amount of cortisol in a sample of your blood, pee or spit (saliva) to be checked. If cortisol is high, you may be referred to a hormone specialist (an endocrinologist) for further tests to check for problems with your pituitary or adrenal glands, such as blood tests and scans.

The Pituitary Foundation explains that the first tests establish whether Cushing's is present, because most people with weight gain, high blood pressure, diabetes or excess hair do not have it. These may include taking a dexamethasone tablet (which should suppress cortisol in people without Cushing's), a series of blood tests, 24-hour urine collection and late-night saliva tests. Further tests then locate the cause, and may include MRI or CT scans, blood sampling from the pituitary veins and bone density tests.

It adds that tests can be complicated, take time and may need to be repeated, and people are often referred to a hospital very familiar with Cushing's.

The NHS says treatment depends on what is causing it and how severe symptoms are. Options include gradually reducing steroid medicine, medicine to control the amount of cortisol your adrenal glands produce, radiotherapy to get rid of a non-cancerous pituitary growth, surgery to remove a growth in the pituitary or adrenal glands, and surgery to remove the adrenal glands, after which you take hormone replacement medicines for the rest of your life.

After treatment, cortisol is checked again, and further treatment may be needed if it is still high, the NHS says.

For a pituitary tumour, the Pituitary Foundation describes surgery through the nose under general anaesthetic (transsphenoidal surgery). Most people are up and about the following day and home within a few days, and should plan 4 to 6 weeks or longer away from work. It says you may need hydrocortisone tablets for some time afterwards while your own system recovers, and that after successful surgery you are likely to feel worse for several weeks and months before you begin to feel better.

The NHS says untreated Cushing's syndrome can cause serious health problems including heart attack and stroke, high blood pressure, type 2 diabetes, an increased risk of blood clots, weakened bones (osteoporosis) and kidney stones. This is why testing and referral matter if you have symptoms, particularly if you are taking steroid medicine.

The NHS says Cushing's syndrome is rare in children, and the main symptoms in a child are obesity and being short for their age. The Pituitary Foundation says it has been diagnosed in children as young as six, and that in children it may show itself by growth stopping and weight increasing.

The NHS says to see a GP if you have symptoms of Cushing's syndrome, particularly if you are taking steroid medicine. The NHS describes reducing steroid medicine gradually, so agree any change with the prescriber rather than stopping tablets yourself.

On the NHS, a GP can arrange initial cortisol tests and refer you to an endocrinologist. The Pituitary Foundation says the tests are complicated and you are likely to be referred to a hospital that is very familiar with Cushing's.

Private endocrinology consultations and tests are available. Whichever route you choose, results of cortisol tests should be shared with your GP, and any plan to change steroid medicine should be agreed with the prescriber.