Calcium blood test

Your body requires calcium to maintain healthy bones and teeth. It’s also essential for keeping your nerves, heart, and muscles functioning properly. Since calcium is important for many of your body’s functions, its levels must be within a tight range.

A second calcium blood test, the ionized calcium blood test, measures the amount of “free” calcium in your blood. “Free calcium” refers to calcium that’s not bound to any proteins and not together with an anion in your blood.

In addition to these two calcium blood tests, the calcium level in your urine can also be measured.

Alternative Names

Ca+2; Serum calcium; Ca++; Hyperparathyroidism – calcium level; Osteoporosis – calcium level; Hypercalcemia – calcium level; Hypocalcemia – calcium level

What is calcium and what does it do?

Calcium is one of the most important and common minerals in your body. About 99% of your body’s calcium is stored in your bones and teeth, while the other 1% of it circulates in your blood. Although it may be a small amount, the calcium in your blood is essential and does the following:

• Helps your nerves work.
• Helps make your muscles squeeze together so you can move.
• 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 to absorb calcium.

There are four main reasons why you may need a calcium blood test, including:

• Your healthcare provider may have ordered routine bloodwork called a basic metabolic panel (BMP) or comprehensive metabolic panel (CMP), which both include a calcium blood test.
• You may be showing signs or symptoms of having too much calcium (hypercalcemia) or too little calcium (hypocalcemia) in your blood.
• If you’ve been diagnosed with a condition that affects the amount of calcium in your blood, you may need routine calcium blood tests to make sure your treatment is working.
• If you take a medication that affects the amount of calcium in your blood, you may need routine calcium blood tests to monitor your levels.

Signs and symptoms of having too much calcium in your blood (hypercalcemia) include:

• More frequent urination and increased thirst.
• Fatigue.
• Headaches.
• Nausea and vomiting.
• Loss of appetite.
• Constipation and abdominal pain.

Signs and symptoms of having too little calcium in your blood (hypocalcemia) include:

• Muscle cramps, especially in your back and legs.
• Dry, scaly skin.
• Brittle nails.
• Confusion.
• Irritability or restlessness.
• Depression.

Severe hypocalcemia (very low levels of calcium in your blood) can cause the following symptoms:

• Tingling in your lips, tongue, fingers, and/or feet.
• Muscle aches.
• Muscle spasms in your throat that make it difficult to breathe.
• Stiffening and spasms of your muscles (tetany).
• Abnormal heart rhythms (arrhythmia).

Your healthcare provider may order a calcium test if you have a medical condition that may affect your calcium levels. Many medical conditions affect your blood calcium levels, including:

• Parathyroid conditions.
• Kidney disease.
• Thyroid disease.
• Malnutrition, especially too little or too much calcium and/or vitamin D in your diet.
• Certain types of cancer.

Certain medications can also affect your blood calcium levels, including:

• Bisphosphonates.
• Corticosteroids.
• Rifampin.
• Calcitonin.
• Chloroquine.
• Cinacalcet.
• Denosumab.
• Foscarnet.
• Plicamycin.
• Hydrochlorothiazide (HCTZ) and other thiazide diuretics.
• Lithium.

Test uses and purpose

Your doctor will typically order a total calcium blood test as part of a routine metabolic panel during a general physical examination.

If you have symptoms of high or low calcium levels, your doctor may order a calcium blood test.

Your doctor may also order a calcium blood test if they suspect that you have kidney disease, parathyroid disease, or cancer.

How to Prepare for the Test

Your healthcare provider may tell you to temporarily stop taking certain medicines that can affect the test. These medicines may include:

• Calcium salts (may be found in nutritional supplements or antacids)
• Lithium
• Thiazide diuretics (water pills)
• Thyroxine
• Vitamin D

Drinking too much milk (2 or more quarts or 2 liters a day or a large amount of other dairy products) or taking too much vitamin D as a dietary supplement can also increase blood calcium levels.

Why the Test is Performed

All cells need calcium to work. Calcium helps build strong bones and teeth. It is important for heart function and helps with muscle contraction, nerve signaling, and blood clotting.

Your doctor may order this test if you have signs or symptoms of:

• Certain bone diseases
• Certain cancers, such as multiple myeloma, a cancer of the breast, lung, neck, and kidney
• Chronic kidney disease
• Chronic liver disease
• Disorders of the parathyroid glands (a hormone made by these glands controls calcium and vitamin D levels in the blood)
• Disorders that affect how your intestines absorb nutrients
• Overactive thyroid gland or taking too much thyroid hormone medicine
• Abnormal vitamin D level

Normal Results

Some laboratories use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A higher-than-normal level may be due to several health conditions. Common causes include:

• Being on bed rest for a long time.
• Consuming too much calcium or vitamin D.
• Hyperparathyroidism (parathyroid glands make too much of their hormone; often associated with a low vitamin D level).
• Infections that cause granulomas such as tuberculosis and certain fungal and mycobacterial infections.
• Multiple myeloma, T cell lymphoma, and certain other cancers.
• Metastatic bone tumor (bone cancer that has spread).
• Overactive thyroid gland (hyperthyroidism) or too much thyroid hormone replacement medicine.
• Paget disease. Abnormal bone destruction and regrowth, causing deformity of the affected bones.
• Sarcoidosis. Lymph nodes, lungs, liver, eyes, skin, or other tissues become swollen or inflamed.
• Tumors producing a parathyroid hormone-like substance.
• Use of certain medicines such as lithium, tamoxifen, and thiazides.

Lower than normal levels may be due to:

• Disorders that affect the absorption of nutrients from the intestines
• Hypoparathyroidism (parathyroid glands do not make enough of their hormone)
• Kidney failure
• Low blood level of albumin
• Liver disease
• Magnesium deficiency
• Pancreatitis
• Vitamin D deficiency

What should I expect during my calcium blood test?

You can expect to experience the following during a blood test, or blood draw:

• You’ll sit in a chair, and a healthcare provider will check your arms for an easily accessible vein. This is usually in the inner part of your arm on the other side of your elbow.
• Once they’ve located a vein, they’ll clean and disinfect the area.
• They’ll then insert a small needle into your vein to take a blood sample. This may feel like a small pinch.
• After they insert the needle, a small amount of blood will collect in a test tube.
• Once they have enough blood to test, they’ll remove the needle and hold a cotton ball or gauze on the site to stop the bleeding.
• They’ll place a bandage over the site, and you’ll be finished.

The entire procedure usually takes less than five minutes

What are the risks of a calcium blood test?

Blood tests are a very common and essential part of medical testing and screening. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.

What do the results mean?

Results from a total calcium test that are higher than normal may be a sign of many types of conditions, such as:

• Overactive parathyroid glands (hyperparathyroidism), a condition in which your parathyroid glands produce too much parathyroid hormone
• Certain types of cancer, including cancer that spreads to the bone
• Bone disorders, including Paget’s disease of the bone
• Taking too much vitamin D over a long period

Results from a total calcium test that are lower than normal may be a sign of:

• Low blood protein levels, which may be caused by liver disease or malnutrition
• Underactive parathyroid glands (hypoparathyroidism), a condition in which your parathyroid glands produce too little parathyroid hormone
• Too little calcium in your diet
• Too little vitamin D or magnesium
• Pancreatitis
• Kidney disease

If your results from a total calcium blood test are not in the normal range, it doesn’t always mean that you have a medical condition that needs treatment. Your diet and certain medicines can affect your calcium levels. If you have questions about your results, talk with your provider

Is there anything else I need to know about a calcium blood test?

A calcium blood test does not tell you how much calcium is in your bones. Bone health can be measured with a type of x-ray called a bone density scan, or dexa scan. A DEXA scan measures the mineral content, including calcium, and other aspects of your bones.