A calcium blood test measures the amount of calcium in your blood. Calcium is one of the most important minerals in your body. You need calcium for healthy bones and teeth. Calcium is also essential for proper functioning of your nerves, muscles, and heart. About 99% of your body's calcium is stored in your bones. The remaining 1% circulates in the blood. If there is too much or too little calcium in the blood, it may be a sign of bone disease, thyroid disease, kidney disease, or other medical conditions.

Other names: total calcium, ionized calcium

There are two types of calcium blood tests:

• Total calcium, which measures the calcium attached to specific proteins in your blood.
• Ionized calcium, which measures the calcium that is unattached or "free" from these proteins.

Total calcium is often part of a routine screening test called a basic metabolic panel. A basic metabolic panel is a test that measures different minerals and other substances in the blood, including calcium.

Your health care provider may have ordered a basic metabolic panel, which includes a calcium blood test, as part of your regular checkup, or if you have symptoms of abnormal calcium levels.

Symptoms of high calcium levels include:

• Nausea and vomiting
• More frequent urination
• Increased thirst
• Constipation
• Abdominal pain
• Loss of appetite

Symptoms of low calcium levels include:

• Tingling in the lips, tongue, fingers, and feet
• Muscle cramps
• Muscle spasms
• Irregular heartbeat

Many people with high or low calcium levels do not have any symptoms. Your health care provider may order a calcium test if you have a pre-existing condition that may affect your calcium levels. These include:

• Kidney disease
• Thyroid disease
• Malnutrition
• Certain types of cancer

If your results show higher than normal calcium levels, it may indicate:

• Hyperparathyroidism, a condition in which your parathyroid glands produce too much parathyroid hormone
• Paget's disease of the bone, a condition that causes your bones to become too big, weak, and prone to fractures
• Overuse of antacids that contain calcium
• Excessive intake of calcium from vitamin D supplements or milk
• Certain types of cancer

If your results show lower than normal calcium levels, it may indicate:

• Hypoparathyroidism, a condition in which your parathyroid glands produce too little parathyroid hormone
• Vitamin D deficiency
• Magnesium deficiency
• Inflammation of the pancreas (pancreatitis)
• Kidney disease

If your calcium test results are not in the normal range, it doesn't necessarily mean that you have a medical condition needing treatment. Other factors, such as diet and certain medicines, can affect your calcium levels. If you have questions about your results, talk to your health care provider.

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