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Normal Calcium & Phosphate

by Matthew Fox, MD

About Matthew Fox, MD

Dr. Matthew Fox graduated from the University of California with a Bachelor of Arts in molecular, cell and developmental biology and received a M.D. from the University of Virginia. He is a pathologist and has experience in internal medicine and cancer research.


Calcium and phosphate both make up important part of a healthy diet, and your body relies on both minerals to function properly. Maintaining healthy levels of both minerals proves important to your heath, so your body tightly regulates your calcium and phosphate levels to ensure they stay within a normal range. Diseases can disrupt normal calcium and phosphate levels, and these abnormal levels can lead to further problems.


Calcium and phosphate are both found in bone. The minerals impart strength to bone and also serve as a reservoir in case the blood levels of calcium or phosphate drop. Calcium is also important in cellular communication. For example, signals from the brain travel through the nerves to tell a muscle to contract. It also plays a role in cell communication. Phosphate can also serve as a chemical messenger, relaying information between cells, and it's also is important for its role in the function of ATP -- a primary source of fuel for your cells.


Normal calcium levels can be measured in the blood as total calcium or free calcium. Total calcium is all the calcium found in a given unit of blood with the normal range being 9 to 10.5 milligrams per deciliter. Free, or ionized calcium, is the measure of calcium that is not bound to protein, such as albumin in the blood. Normal ionized calcium levels are 4.5 to 5.6 milligrams per deciliter. Phosphate levels are normally milligrams per deciliter.


Your intestines absorb the calcium from your diet. This process is regulated by vitamin D, which is obtained in the diet or synthesized by sunlight in the skin. The kidneys excrete and reabsorb calcium depending on the blood levels. In addition, the bone provides calcium to the blood if needed. Parathyroid hormone and vitamin D increase calcium levels, and calcitonin, also released by the parathyroid, decreases calcium levels. Phosphate levels are decreased by parathyroid hormone and increased by vitamin D.


Abnormal calcium levels tend to cause nerve and muscle dysfunction. Cancer and overly active parathyroid glands, called hyperparathyroidism, are two common causes of high calcium. Kidney failure is a common cause of low calcium, largely through the decreased synthesis of vitamin D. In contrast, kidney failure tends to cause high phosphate levels, which can lead to complications such as hardening of the arteries. Low phosphate levels are caused by a number of conditions, including hyperparathyroidism and diarrhea.

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.