Cushing’s syndrome is a group of symptoms caused by too much cortisol in your body. It can be caused by long-term use of corticosteroid medications or by a non-cancerous tumour in your pituitary or adrenal glands.
- Cortisol is a hormone produced by your body that helps in many ways, including controlling blood sugar levels, maintaining blood pressure and reducing inflammation. It also plays an important role in how your body deals with stress.
- If you are taking corticosteroid medications (e.g. prednisone) for a long time, your body may build up high levels of cortisol, causing Cushing’s syndrome.
- Cushing’s syndrome may also be caused by pituitary and adrenal gland tumours. This can be hard to diagnose.
- Common symptoms are weight gain, increased blood pressure and changes in mood.
- Cushing’s syndrome is treatable.
What causes Cushing’s syndrome?
Cushing’s syndrome is caused by too much cortisol in your body. Your body can build up too much cortisol in two ways:
- long-term use of corticosteroid medications
- adrenal glands producing too much cortisol.
Long-term use of corticosteroid medications
Corticosteroid medications (e.g. prednisone, hydrocortisone) contain a man-made version of cortisol and are used to treat many conditions associated with inflammation, such as rheumatoid arthritis, lupus or asthma, or they can be used to prevent your body from rejecting a transplanted organ.
Corticosteroids can be taken orally, inhaled (e.g. for asthma) or topically (put on your skin). Short-term use of oral corticosteroids and the use of inhaled and topical corticosteroids carry a very low risk of developing Cushing’s syndrome. Long-term use of oral corticosteroids carry a higher risk.
Adrenal glands producing too much cortisol
Cortisol is a hormone, which means it is made in one part of your body but causes an effect in another part. Cortisol is made by your adrenal glands, which sit on top of your kidneys.
Too much cortisol is produced if you have a tumour in your adrenal glands, pituitary gland or, occasionally, elsewhere in your body, e.g. your lungs.
Adrenal gland tumour
A tumour in your adrenal glands can cause too many adrenal cells to produce cortisol. This causes high levels of cortisol in your blood.
Pituitary gland tumour
Your adrenal glands need to be told how much cortisol to make. Your pituitary gland, which is found just below your brain, has the job of telling your adrenal glands how much cortisol your body needs. This is a four-step process:
- Your pituitary gland makes a hormone called adrenocorticotropic hormone (ACTH). The hypothalamus (a small section of your brain) tells the pituitary gland how much ACTH to make.
- ACTH travels in your blood from your pituitary gland to your adrenal glands.
- Your adrenal glands make cortisol.
- Once enough cortisol is made, your pituitary gland stops making ACTH.
A tumour in your pituitary gland is called Cushing’s disease.
A tumour elsewhere in your body
In very rare cases, a tumour in another part of your body, often the lungs, starts producing ACTH, causing your adrenal glands to produce more cortisol than is needed. Cushing’s syndrome caused by a tumour is five times more common in women than men and it usually occurs between the ages of 25–40.
What are the symptoms of Cushing’s syndrome?
There are many symptoms of Cushing’s syndrome and you may only have a few. Symptoms vary from person to person and can range from mild to severe.
The most common symptoms are:
- weight gain, especially around your stomach, between your shoulders and upper back
- a red, round, moon-shaped face
- purple stretch marks around your arms, stomach and thighs
- increased blood pressure.
Cushing’s syndrome can also cause changes to your skin, bones, muscles and mood.
- Skin changes: thin skin that bruises easily, slow-healing cuts or an increase in face and body hair in women.
- Bone and muscle changes: osteoporosis (thin and weak bones) and muscle weakness, especially in your upper legs and arms.
- Mood changes: problems with memory and concentration and feeling tired all the time.
Other symptoms include diabetes, irregular periods in women and an increase in infections.
How is Cushing's syndrome diagnosed?
Often the diagnosis of Cushing’s syndrome can take some time, as many of the symptoms can be caused by other disorders. If your doctor suspects Cushing’s syndrome, you may need to have a blood test, a urine test and a saliva test.
You may be sent for a blood test that measures how much cortisol you have in your blood.
- The amount of cortisol in your blood changes during the day so a single blood test is not enough for a diagnosis.
- If your blood test shows you have a high level of cortisol you may need to have a dexamethasone suppression test.
- For a dexamethasone suppression test, you will need to take an oral dose of dexamethasone at midnight and then have a blood test at 8 am the next morning.
- Dexamethasone is a medication that stops your body producing cortisol. If you have Cushing’s syndrome, dexamethasone will not change how much cortisol your body makes.
You may be asked to collect your urine (wee) over 24 hours. The amount of cortisol in your urine is measured.
Cushing’s syndrome can cause increased levels of cortisol at night. You might be asked to collect a sample of your saliva late at night. If you are diagnosed with Cushing’s syndrome due to a tumour, further testing will be needed to find out where the tumour is. These may include an MRI, ultrasound or further blood tests.
What is the treatment for Cushing's syndrome?
Treatment depends on what is causing your high level of cortisol. The goal of treatment is to reduce the amount of cortisol.
Corticosteroid medication use
If your corticosteroid medication is causing Cushing’s syndrome your doctor may try lowering your dose of corticosteroid medication gradually to minimise symptoms while still treating the disease it is being used for, by trying you on a different, non-corticosteroid medication.
It is important not to reduce the dose of your corticosteroid medication or stop taking it on your own. Do so only under your doctor's supervision. Stopping these medications suddenly could lead to low cortisol levels which may be harmful. Slowly tapering off corticosteroid medications allows your body to restart normal cortisol production.
Pituitary or adrenal gland tumour
If a pituitary or adrenal gland tumour is causing Cushing’s syndrome your treatment options may be surgery to remove the tumour or radiation or chemotherapy.
What self-care can I do if I have Cushing's syndrome?
- Be familiar with the symptoms of Cushing’s syndrome if you are on long-term corticosteroid medication.
- Discuss any symptoms you may have with your doctor.
- Take your corticosteroid medication as prescribed.
- Don’t stop taking your corticosteroid medication without your doctor's help, as your body may have stopped producing enough cortisol, which can cause serious harm.
- Once the underlying cause of your Cushing’s syndrome has been treated, you should start to feel better and have more energy. It’s important to continue to exercise daily but avoid high impact exercises due to your increased risk of osteoporosis. Your doctor can recommend appropriate exercises.
- Make sure you eat a healthy diet high in calcium and Vitamin D to help maintain and strengthen your bones.
- Cushing’s syndrome can cause changes to your mood. Look after your mental health and seek help from a healthcare professional if your mood hasn’t improved once your symptoms are being managed.
- Cushing’s syndrome can be very serious if left untreated. As it can be hard to diagnose, don’t give up seeking advice and tests from your healthcare professional if you notice any symptoms
Cushing Syndrome - causes, symptoms, diagnosis, treatment, pathology
(Osmosis, US, 2017)
Information for healthcare providers
Dexamethasone suppression test Canterbury Health Laboratories
Cushing's syndrome – update on signs, symptoms and biochemical screening European Journal of Endocrinology, 2015
Cushing’s syndrome DermNet NZ, 2005
The NZ laboratory schedule and test guidelines – biochemistry tests BPAC, NZ, 2014