Blood calcium test: definition, process, and explanation of test results

Definition

What is blood calcium?

The blood calcium test checks the level of calcium in the body that is not stored in the bones. Calcium is the most common mineral and one that is essential for the body. The body needs it to build and repair bones and teeth, helps nerves work, helps muscles, helps blood clot, and helps the heart work. Almost all of the calcium in the body is stored in the bones.

Generally, calcium levels in the blood are carefully controlled. When blood calcium levels become low (hypocalcemia), the bones secrete calcium to restore normal levels of calcium in the blood. When the calcium in the blood is high (hypercalcemia), excess calcium that is stored in the bones will be excreted from the body through urine and feces. The amount of calcium in the body depends on the amount of:

• the calcium you get from food
• calcium and vitamin D that your digestion absorbs
• phosphate in the body
• certain hormones, including parathyroid hormone, calcitonin and estrogen in the body

Vitamin D and this hormone help control the amount of calcium in the body. They also control the amount of calcium you absorb from food and which you excrete from your body in your urine. The level of phosphate in the blood is closely related to the level of calcium and the two work in opposite ways: when blood calcium becomes high, the phosphate level decreases, and vice versa.

It is important to get the right amount of calcium in your diet because the body loses calcium on a daily basis. Foods rich in calcium include dairy products (milk, cheese), eggs, fish, green vegetables and fruits. Most people who have high or low calcium levels don't experience any symptoms. It takes very high or low levels of calcium to cause symptoms.

When should I take blood calcium?

A calcium blood test can be part of screening for a wide variety of diseases and conditions, including osteoporosis, cancer, and kidney disease. This blood test may also be needed to monitor ongoing treatment for other conditions, or to check for unwanted side effects from the medicines you are taking. Your doctor may order this test if he suspects the following conditions:

• bone diseases, such as osteoporosis or osteopenia
• cancer
• chronic kidney or liver disease
• parathyroid gland disorders
• malabsorption or a disorder that affects the body's absorption of nutrients
• an overactive or passive thyroid gland

Precautions & warnings

What should I know before taking blood calcium?

Newborns, especially those who are premature and with below average body weight, are usually monitored for the first few days after birth for neonatal hypocalcemia using a calcium ionization test. This can occur because the parathyroid glands have not developed and symptoms do not always appear. This condition can resolve on its own or requires treatment with calcium supplements, given orally or intravenously. Measurement of calcium in blood and urine cannot explain the amount of calcium in bones. A test similar to an X-ray, called a bone density or "dexa" scan, is used for this purpose.

The thiazide diuretic drug is the most commonly used induction drug for high calcium levels. Lithium or tamoxifen can also increase a person's calcium levels.

Process

What should I do before taking blood calcium?

Do not use calcium supplements for 8 to 12 hours before having a blood calcium test. Your doctor will tell you to temporarily stop using some medications that could affect the test. These drugs include:

• calcium salts (can be found in nutritional supplements or antacids)
• lithium
• thiazide diuretic
• thyroxine
• vitamin S

How does blood calcium process?

The medical personnel in charge of drawing your blood will take the following steps:

• wrap an elastic belt around your upper arm to stop blood flow. This makes the blood vessel under the bundle enlarge making it easier to insert the needle into the vessel
• clean the area to be injected with alcohol
• inject a needle into a vein. More than one needle may be required.
• Insert the tube into the syringe to fill it with blood
• untie the knot from your arm when enough blood is drawn
• sticking gauze or cotton on the injection site, after the injection is complete
• apply pressure to the area and then put a bandage on

What should I do after taking blood calcium?

An elastic band is wrapped around your upper arm and will feel tight. You may not feel anything when you get the injection, or you may feel like you are stung or pinched.

If you have questions related to this test process, please consult your doctor for a better understanding.

Explanation of the Test Results

What do my test results mean?

Normal value

The normal value of the level can be slightly different in each laboratory. Some laboratories use different measurements or types of tests. Talk to your doctor about what your test results mean.

Total Calcium
Adult	8.8–10.4 milligrams per deciliter (mg / dL) or 2.2–2.6 millimoles per liter (mmol / L)
Children	6.7–10.7 milligrams per deciliter (mg / dL) or 1.90–2.75 millimoles per liter (mmol / L)

Normal blood calcium values ​​in older people are lower. Normal blood calcium values ​​are higher in children because their bones grow rapidly. The calcium ionization test checks the amount of protein-free calcium in the blood. The level of calcium ionization in the blood is not affected by the amount of protein in the blood.

Ionization of Calcium
Adult:	4.65–5.28 mg / dL or 1.16–1.32 mmol / L
Children:	4.80–5.52 mg / dL or 1.20–1.38 mmol / L

High marks

High calcium values ​​can be caused by:

• hyperparathyroidism
• cancer, including cancer that has spread to the bones
• tuberculosis
• lying down too long after a fracture
• Paget's disease

Low marks

Low calcium values ​​are caused by:

• low levels of albumin protein in the blood (hypoalbuminemia)
• hypoparathyroidism
• high levels of phosphate in the blood, caused by kidney failure, use of laxatives, and other things
• malnutrition caused by celiac disease, pancreatitis, and alcoholism
• osteomalacia
• ricket

Depending on the laboratory of your choice, the normal range of a blood calcium test may vary. Discuss any questions you have about your medical test results with your doctor.