High calcium levels (hypercalcaemia, hypercalcemia)

What are the symptoms of high calcium (hypercalcaemia)?

Many of the symptoms of high calcium are common in advanced cancer, even in people who do not have high blood calcium levels. You might not have any definite symptoms. You may just feel a bit unwell or very tired.

How serious your symptoms are doesn’t always match up to the calcium level in your blood. It is important to talk to your doctor if you are worried that you might have a high blood calcium level. People with a slightly high calcium level can have very severe symptoms and people with a very high calcium level might only have mild symptoms.

Your doctor will do a blood test if they think that the levels might be high.

First symptoms

Some of the first symptoms that your blood calcium level might be higher than normal include: 

• feeling more tired than usual

• feeling weak

• not wanting to eat much

• constipation

• loss of concentration and interest in doing things

• mild confusion

• low mood

• irritability

Further symptoms

If you don't have treatment your symptoms can become much worse. It could lead to you becoming unconscious and eventually be life threatening. The symptoms of untreated high calcium levels can include:

• feeling and being sick

• drowsiness

• passing large amounts of urine

• feeling very thirsty or dehydrated

• confusion or agitation

• muscle spasms

• tremors

• bone pain and weakness

• irregular heartbeat

• difficulty thinking and speaking clearly

Brain and spinal cord symptoms

Calcium plays a role in the normal working of the brain and spinal cord. So if you have severely high calcium levels you might also:

• have fits (seizures)

• be unable to coordinate muscle movement, which can affect walking, talking and eating

• have changes in personality

Why does cancer sometimes cause high calcium?

Normally the body controls the level of calcium in the blood very well. High blood calcium levels in the body can happen if:

• your cancer is interfering with the control of the amount of calcium in the bloodstream 

• you have cancer in your bones which is causing a release of calcium into the bloodstream

• you have dehydration from being sick or having diarrhoea, this is not a common cause 

Find out about calcium and how your body controls the levels in your blood

Which cancers might cause high calcium?

The types of cancers that are most commonly associated with high blood calcium are:

• myeloma

• breast cancer

• lung cancer

• kidney cancer

• prostate cancer

Although less common, high blood calcium can happen in other types of cancer.

Find your cancer type

Can you prevent high calcium?

Cancer that has spread (​advanced cancer​ ) can cause high calcium levels. It is not really possible to prevent it from happening. It is not caused by anything in your diet so you shouldn't need to alter what you eat. 

Recognising the symptoms of high blood calcium is important so that you can ask your doctor for help as soon as possible.

What treatment will I have?

The type of treatment you have depends on how high your calcium levels are and how severe your symptoms are.

For example, you have urgent treatment with fluids and bisphosphonate drugs if you have moderate to severe high calcium, or severe symptoms. You still need treatment, but less urgently, if it is mild high calcium. You might just need bisphosphonate treatment if you are able to drink plenty of fluids.

Treatment relieves some symptoms more quickly than others. For example, sickness, constipation and thirst are much easier to relieve than tiredness and loss of appetite.

It may not be possible to control high calcium if your cancer is very advanced and you are in the final days or weeks of life. But your doctors will do all they can to help make you as comfortable as possible.

Follow up

Once your blood calcium levels go back to normal, your doctor will want to keep a close eye on you. You will have regular blood and urine tests to make sure the treatment is still working.

It is very important that you see your doctor as soon as possible if you feel the symptoms of high calcium are coming back. Even if something else is causing your symptoms, it is better to see your doctor to find out for sure.

You might worry about eating foods that contain calcium if you have high calcium or think you may be at risk of it. But cutting down on these foods will not help high calcium that is caused by cancer. It will not make any difference to your calcium levels.

Do talk to your doctor or nurse if you are concerned about your diet. Make sure you check with your doctor before taking any vitamin or mineral supplements.

Read more about diet and cancer