Hypercalcemia: What’s Causing a Too-High Calcium Level in Your Blood?

How to know you have elevated calcium, and what to do about it

Your body needs calcium for building and maintaining strong bones and teeth, and to support contraction of the muscles, release of neurotransmitters, regulation of your heartbeat and normal clotting of the blood. But having high blood calcium levels can be harmful.

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Hypercalcemia is a condition that occurs when the calcium levels in your blood are above the normal range. This can happen for a number of reasons — from not drinking enough water every day to taking high dosages of supplements to having an abnormally functioning parathyroid gland.

While mildly elevated calcium may not cause any symptoms at all, very high calcium levels can result in abdominal pain, kidney stones, excessive thirst, bone pain, muscle weakness and confusion.

Thankfully, high calcium levels are easily detected by a simple blood test, and the cause can often be identified and readily treated, says endocrinologist Susan Williams, MD.

“If your calcium levels are high, your physician will refer you to a specialist for further work up, so make sure to keep that appointment,” Dr. Williams says.

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How do you know your calcium is high?

Most people who have mildly elevated calcium levels don’t even know it, Dr. Williams says.

“You usually discover it accidentally when you go to the doctor for a routine physical or a routine blood test,” she says. “Anyone can get hypercalcemia. Sometimes family history can play into it if you have a history of kidney stones, but anyone can develop it at any stage of life.”

Symptoms of hypercalcemia, though uncommon, can include:

  • Frequent urination and thirst
  • Fatigue and bone pain
  • Abdominal pain and constipation
  • Forgetfulness and confusion
  • Lethargy and depression
  • Muscle aches

What’s causing your hypercalcemia?

There are many things that can cause hypercalcemia including several diseases, medications and even dehydration. But the main causes are:

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  • Overactive parathyroid glands. Hyperparathyroidism means your body releases excess parathyroid hormone, which can elevate your blood calcium level. “When the calcium is high because of an overactive parathyroid gland, that means the calcium is coming from the bones, and that can result in fractures,” Dr. Williams says.
  • Supplements and antacid tablets. Taking too much calcium in the form of calcium supplements or calcium-based antacid tablets is another common cause. “Be very careful about calcium-rich antacid tablets,” Dr. Williams says. “Taking an occasional tablet is not harmful. But if you’re taking more than one or two per week, let your primary care physician know. That’s a may be a sign of a digestive problem that may need to be addressed.”
  • Cancer. Some patients fear cancer is the reason for their high calcium levels. If your levels spike suddenly into the 12 to 15 mg/dL range (10 mg/dL is normal), it could be the first sign of cancer, but this is a far more rare reason for elevated calcium, Dr. Williams says.

Support healthy calcium levels

The current recommendations from the National Osteoporosis Foundation are to include plenty of foods high in calcium in your diet, including dairy products, dark leafy greens and products fortified with calcium.

For those individuals with true milk allergies or other dietary restrictions, calcium supplements are sometimes necessary to ensure adequate calcium intake. But caution is advised.

Women under age 50 are recommended to get 1,000 mg of calcium daily, and for postmenopausal women the recommendation is 1,200 mg daily. For men under age 70, the recommendation is to get 1,000 mg daily. That increases to 1,200 mg for men over age 70.


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