Calcium is one of the most important and common minerals in your body. Around 99% of your body’s calcium is stored in your bones and teeth, while the other 1% of it circulates in your blood in both 'free' and 'bound' forms.

Although there is only a small amount, the calcium in your blood is essential and does the following:

• Helps your nerves work
• Helps make your muscles contract
• Helps your blood clot if you are bleeding
• Helps your heart work properly

The levels of calcium in your blood and bones are controlled by two hormones called parathyroid hormone (PTH) and calcitonin. Vitamin D also plays an important role in maintaining calcium levels because your body needs it in order to absorb calcium.

All of our tests are carried out by trained phlebotomists in over 350 venues across the UK and Ireland. We only carry out in-person tests as this guarantees the accuracy of your test results and enables us to get your samples to the laboratory for testing quickly, therefore giving you results faster.

You do not need to fast before your calcium blood test unless you have been specifically directed to do so.

Low calcium blood levels, also called hypocalcaemia, means that you do not have enough calcium in your blood. The most common cause of this is low protein levels, especially low albumin, so your doctor may investigate this also. Other causes include deficiencies in dietary calcium, vitamin D and magnesium or conditions such as chronic kidney disease, chronic gastrointestinal disease or bone disease.

Calcium is particularly important to maintain bone growth and for post-menopausal women who may develop low bone mass and be at risk of osteoporosis. A healthy diet should be sufficient but you may wish to consider a supplement such as supplemental vitamin D, which is a common cause of low calcium levels. It's important to discuss with your doctor first the risks and benefits of any supplementation before you start.

Medications and supplements that can influence the results of a calcium blood test include calcium salts (for example, nutritional supplements or antacids), vitamin D, lithium, thiazide diuretics, and thyroxine.

Never stop taking prescribed medications without first consulting with a doctor.

You don’t need to prepare for a calcium blood test, but if you are taking medications or supplements that may affect your calcium blood levels, you may wish to discontinue them 24 hours before the test. Only discontinue prescribed medicines after seeking advice from your prescribing doctor.

Otherwise, there is no special preparation needed for a calcium blood test.

High calcium levels are known as hypercalcaemia, meaning you have too much calcium in your blood. As about half of the calcium in your blood is bound by the protein albumin, your doctor may also check if this is at normal levels or not.

There are many causes of high blood calcium, including high parathyroid hormone levels, bone cancers (both primary bone cancers and other cancers that spread to bones), or other disorders such as sarcoidosis. If your calcium blood test results are high your doctor will need to further investigate to find the root cause.