Calcium Blood Test

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A calcium blood test is used to measure the levels of calcium in the blood. Calcium plays an important role in many functions of the body, including nerve and muscle function, bone development and repair, and controlling heart rhythm.

The most common reason for ordering a calcium blood test is to screen for or rule out problems with parathyroid glands or kidneys that are causing abnormal calcium levels. This type of test can also be ordered when someone has symptoms such as bone pain, muscle spasms, fatigue, loss of appetite, nausea or vomiting. The results from this type of test can help your doctor determine if you need treatment for conditions like hyperparathyroidism (high levels of parathyroid hormone), kidney disease, Paget's disease, or other types of disorders.

Calcium blood test results are usually reported in milligrams (mg) per deciliter (dL), which is the same as parts per million (ppm). Normal levels can vary slightly based on gender and age, but generally, adults should have calcium levels between 8.5 to 10.2 mg/dL for women and 9.0 to 10.5 mg/dL for men. Very high or low levels can indicate health problems that require further testing to determine the cause and best treatment options. If you think that you might need a calcium blood test, talk to your doctor about your symptoms and whether this type of screening would be appropriate for you.

There are several different types of calcium blood tests that can be ordered, each with a slightly different purpose. Some of the most common tests include:

Total calcium test: This is the standard test used to evaluate overall calcium levels in the blood.

Serum calcium test: Measures only the ionized (free) form of serum calcium, which can be affected by parathyroid hormone and other factors that are different from what is measured with a total calcium blood test.

Intact PTH assay: Measures how much parathyroid hormone is being produced by the parathyroid glands in response to low serum calcium levels. This type of test is usually ordered if you have signs or symptoms of hyperparathyroidism, including kidney stones, bone pain and fractures, weakness or fatigue, frequent urination and/or constipation, nausea and vomiting, and loss of appetite.

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Urine calcium-to-creatinine ratio: Measures the amount of calcium being excreted in urine, which can indicate possible kidney problems. This test is usually recommended if someone has signs or symptoms of kidney disease, such as swelling in your legs and ankles, loss of appetite, nausea and vomiting, weakness or fatigue, difficulty concentrating or confusion.