Calcium (Ca) in Blood

Blood Calcium

Results

A test for calcium in the blood checks the calcium level in the body that is not stored in the bones.

Normal

Calcium in blood

Adults:	2.25–2.75 millimoles per litre (mmol/L) or 9.0–10.5 milligrams per decilitre (mg/dL)

Normal values may vary from lab to lab.

Normal blood calcium values are higher in children because their bones are growing quickly.

Calcium in blood

Children:	1.9–2.7 millimoles per litre (mmol/L) or 7.6–10.8 milligrams per decilitre (mg/dL)

An ionized calcium test checks the amount of calcium that is not attached to protein in the blood. The level of ionized calcium in the blood is not affected by the amount of protein in the blood.

Ionized calcium

Adults:	1.1–1.3 mmol/L or 4.65–5.28 mg/dL

High values

• High levels of calcium in the blood may be caused by being on bed rest for a long time, hyperparathyroidism, kidney disease, tuberculosis, or cancer that has spread to the bones. Certain cancers can make a substance that causes high blood calcium levels.
• High levels of calcium in the blood can be caused by eating a diet with too much vitamin D, vitamin A, or calcium. Eating large amounts of milk products or taking too many calcium medicines, such as antacids or vitamin supplements, can also cause high blood calcium levels.
• High levels of calcium in the blood can be caused by dehydration, sarcoidosis, chronic liver or kidney problems, Paget's disease, and Addison's disease.
• In rare cases, hyperthyroidism may cause high blood calcium levels.
• In a person with cancer, a high blood calcium level is an emergency. Treatment must be started immediately to prevent the person from becoming confused and dehydrated.

Low values

• Low levels of calcium in the blood can be caused by parathyroid gland (hypoparathyroidism) problems, problems with your intestines that stop your body from absorbing calcium and other nutrients from food (malabsorption syndrome), bone problems, kidney disease, acute pancreatitis, or low amounts of the protein albumin in the blood (hypoalbuminemia).
• Low ionized calcium levels may be caused by low magnesium levels.
• Pregnant women and older men may also have low calcium levels.

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Author:	Jan Nissl, RN, BS	Last Updated: January 10, 2007
Medical Review:	Martin Gabica, MD - Family Medicine Adam Husney, MD - Family Medicine Philip Belitsky, MD, FRCSC - Urology
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