Calcium Test

Calcium is an essential mineral; it is primarily found in the bones (99% of calcium supplies) and the remaining supplies circulate around the body in the bloodstream. Half of the calcium in the body is known as ’free’ or ionised calcium; this means it is used in its original form by the body. The other half of the calcium is known as ’bound’ calcium; it is bound to proteins and other substances in the body and is inactive.

When is the test used?

The test is used to measure the amount of calcium in the blood; it can be used as a routine test but is usually used when patients have symptoms of low calcium, too much calcium or kidney disease. Symptoms of low calcium include muscle cramps, abdominal pain and tingling in the fingers, while symptoms of high calcium include tiredness, nausea, loss of appetite, constipation and vomiting.

Some patients with health conditions, including breast, lung and kidney cancer or kidney disease may also have regular calcium tests to monitor their condition and check the progress of their treatment.

How is the test done?

The test is done by collecting a blood sample from a vein in the arm; a needle is inserted into the vein and the blood is collected in a syringe. Once the sample has been collected, it will be bottled, labelled with the patient’s name and then sent away to the laboratory for analysis.

If blood calcium levels are abnormal, a timed urine collection test may also be carried out. A urine test may also be ordered if the patient has kidney stones.

What do the test results show?

A normal test result indicates that the body is not experiencing any problems with calcium metabolism. The test is usually carried out alongside an albumin test.

If levels of calcium are high (this is known as hypercalcaemia) this may be caused by a number of different health conditions, including:

  • Hyperparathyroidism: this is an overactive parathyroid gland, which is usually caused by a benign tumour
  • Cancer: cancer can cause calcium levels to rise when it spreads to the bones
  • Hyperthyroidism (overactive thyroid gland)
  • Tuberculosis
  • Excess vitamin D

Low levels of calcium (known as hypocalcaemia) may be caused by several different conditions, including:

  • Hypoparathyroidism (underactive parathyroid gland)
  • Decreased levels of vitamin D
  • Low levels of protein
  • Chronic kidney disease
  • Deficiency of magnesium
  • Bone disease
  • Alcoholism
  • Malnutrition

Specific Blood Tests



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