Calcium increases the strength of your bones and teeth and helps your muscles and nerves function. A serum calcium blood test measures the total calcium in your blood. These include ionized calcium, calcium bound to other minerals called anions, and calcium bound to proteins like albumin.
A serum calcium test usually checks the total amount of calcium in your blood. This includes ionized calcium and calcium bound to proteins and anions. Your doctor may want to check your blood calcium levels if you have signs of kidney disease, certain kinds of cancers, or problems with your parathyroid gland.
Ionized calcium levels give more information about active, ionized calcium. It may be important to know your ionized calcium levels if you have abnormal levels of proteins, such as albumin, or immunoglobins in your blood. If the balance between bound calcium and free calcium isn’t normal, it’s important to find out why. Free calcium and bound calcium each typically make up half of your body’s total calcium. An imbalance can be a sign of a major health issue.
An ionized calcium test uses a small amount of your blood. A healthcare professional will get a blood sample by performing a venipuncture. They’ll clean a section of skin on your arm or hand, insert a needle into your vein through your skin, and then draw a small amount of blood into a test tube.
Normal levels of ionized calcium are different in adults and children. In adults, a level of 4.64 to 5.28 milligrams per deciliter (mg/dL) is normal. In children, a normal ionized calcium level is 4.8 to 5.52 mg/dL.
If you have low levels of ionized calcium in your blood, it can indicate:
- hypoparathyroidism, which is an underactive parathyroid gland
- malabsorption of calcium
- a vitamin D deficiency
- acute pancreatitis, which is an inflammation of the pancreas
- kidney failure
If you have a high level of ionized calcium in your blood, it can indicate:
- hyperparathyroidism, which is an overactive parathyroid gland
- a sedentary lifestyle or lack of mobility
- multiple myeloma, which is cancer of the plasma cells (a type of white blood cell that produces antibodies)
- a kidney transplant
- certain kinds of tumors
- an overdose of vitamin D