Treatment for Cushing's syndrome depends on what's causing high levels of cortisol to accumulate in your body.
If your Cushing's syndrome is caused by the long-term use of corticosteroids (iatrogenic Cushing's syndrome), you'll need to gradually reduce your dosage to the lowest possible dose required to control the condition being treated.
If your Cushing's syndrome is caused by a tumour (endogenous Cushing's syndrome), the following treatment options are available:
Reducing corticosteroid use
It's usually not safe to suddenly stop taking corticosteroids. If you've been taking corticosteroids for a long time, your body may stop producing natural steroids.
If you suddenly stop taking your medication, you may experience symptoms such as fatigue, vomiting and diarrhoea. You may also need to continue taking your medication until the symptoms of the condition being treated are under control.
If you've only been taking corticosteroids for less than two weeks, it should be possible to safely stop the dose straight away.
There's no "one size fits all" plan for withdrawing treatment with corticosteroids. However, for most people, a gradual reduction is recommended. A blood test can be used a bit later to tell if your body's producing natural steroids.
It's only safe to stop taking steroids completely once your body is producing them naturally. This can take from a few months to more than a year. During this time you may need treatment for some of the symptoms of Cushing's syndrome, such as medication to lower your blood pressure.
Cortisol-inhibiting medications are designed to block the adverse effects of cortisol. They tend to be used short term leading up to surgery, or after surgery or radiotherapy, to help make these treatments more effective.
Occasionally, cortisol-inhibiting medications are used on a long-term basis in people unwilling or unable to have surgery. Ketoconazole and metyrapone are two widely used cortisol-inhibiting medications.
Ketoconazole isn't licensed for the treatment of Cushing's syndrome. This means the manufacturers designed and tested the medication for treating another condition (fungal infection) and it was subsequently found to also be useful for treating Cushing's syndrome.
Find out more about medicines licensed to treat Cushing's syndrome.
Surgery may be needed to remove a tumour in the pituitary or adrenal glands. Removing a tumour from the lungs is much more challenging and may not be possible.
Pituitary gland removal
Surgery to remove a tumour in the pituitary gland is known as transsphenoidal adenoectomy. Under general anaesthetic, the surgeon removes the pituitary tumour either through your nostril or an opening made in your upper lip.
This type of surgery has a good track record of success. More than 80% of cases where the pituitary tumour is 10mm or smaller are cured. For larger tumours, the cure rate is around 50%. Sometimes a second surgical procedure is recommended if the first operation wasn't successful.
Adrenal gland removal
In most cases, only one adrenal gland will need to be removed. To do this, laparoscopic (keyhole) surgery is usually used. The surgeon makes a small incision in your abdomen and passes tiny instruments through it to remove your adrenal gland.
The advantage of keyhole surgery is that you'll feel less pain after the operation and have minimal scarring. Laparoscopic surgery has a good record of success, with more than 65% of people's symptoms being completely cured.
In more difficult or complex cases, removing both of your adrenal glands may be recommended so they're unable to produce any cortisol. This may be needed if your Cushing's syndrome symptoms are difficult to control in other ways and are putting your long-term health at risk. For example, this could be if you have poorly controlled high blood pressure (hypertension).
If the tumour is located deep inside your lung, it may not be possible to destroy or remove it safely without seriously damaging the lung.
An alternative approach may be recommended, such as using cortisol-inhibiting medication or completely removing the adrenal glands to stop the production of cortisol.
Radiotherapy may be recommended if pituitary gland surgery doesn't achieve a cure or if you're unable to have surgery. It involves using high-energy X-rays to shrink the tumour and stop it producing adrenocorticotropin hormones (ACTH).
Normal radiotherapy is delivered daily in small doses over a period of five weeks. This helps to reduce damage to other areas of the brain.
However, a type of radiotherapy known as stereotactic radiosurgery (SRS) is increasingly being used to treat pituitary tumours. This uses a series of movable frames to hold your head in a precise position. A computer is then used to send energy rays to the exact location of the pituitary tumour.
The precise focusing of SRS is thought to minimise the chances of other parts of your brain being accidentally damaged. The whole radiation dose is delivered in just one session. As the procedure is only available at a number of specialised centres, it's likely you'll have to travel to receive treatment.
Both types of radiotherapy have advantages and disadvantages. Both have a good chance of curing Cushing's syndrome, but their effects may be slow and take months or years to reach full effect.
Complications of surgery
Complications can sometimes develop after surgery for Cushing's syndrome. Pituitary and adrenal operations carry a small risk of infection, bleeding, or anaesthetic complications.
Low cortisol level after surgery
Successful treatment to remove a pituitary or adrenal tumour leaves the body with abnormally low cortisol levels.
Most people need to take two to three tablets of replacement hydrocortisone a day. Treatment can be stopped if your glands recover their normal function after a few months, but it may be needed for several years.
If you have both of your adrenal glands removed, you'll permanently lose the ability to make cortisol. This requires long-term hydrocortisone replacement.
It may take a while to find the right dose of hydrocortisone, but most people tolerate the treatment well.
Loss of other pituitary hormonal function
The surgeon will try to save as much of your pituitary or adrenal gland as possible so they can still produce hormones. However, in some cases this may not possible, particularly if you have a large tumour.
Radiotherapy of any kind also increases your risk of losing normal hormonal function. If you lose normal hormonal function, you'll need to take man-made (synthetic) hormones, which are given as tablets or self-administered injections.
The pituitary gland controls production of cortisol, thyroid hormone, growth hormone, testosterone (in men), oestrogen (in women) and vasopressin (which controls water balance). After treatment for Cushing's syndrome, some people need some or all of these hormones replaced.
Nelson's syndrome is very rare. It's a condition that sometimes develops after an operation to remove both adrenal glands.
Nelson's syndrome is a tumour inside your pituitary gland that grows fairly rapidly over a period of month. The symptoms include:
Treatment for Nelson's syndrome may involve surgery to remove the tumour, and often radiotherapy. Sometimes a tablet form of chemotherapy is used called temozolomide.