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What is calcium?

Calcium is a mineral in the human body. It helps bone, teeth, nerves, and muscles grow and function. It also helps the blood clot. Staff members take blood samples to check the amount of calcium in the body. If the level is too high or too low, the staff may make changes to medicines or fluids that the patient is receiving.

Hypocalcemia (not enough calcium in the blood)

Hypocalcemia can occur:

  • When your body is not getting enough calcium by mouth;
  • When your body is not absorbing the calcium well;
  • When the levels of albumin or magnesium in the blood is low;
  • When your blood has a high level of phosphorus;
  • When you are taking certain medicines; or
  • If you have a vitamin D deficiency or a parathyroid imbalance.

Amifostine is a medicine that can cause low calcium in the blood.

You can receive calcium to increase the amount of this mineral in your blood. It is available as a 500 mg chewable tablet (Tums®), a 500 mg soft chew (Viactiv®), a 600 mg tablet with vitamin D (Caltrate®), a white liquid that can be given by mouth, and a clear liquid that can be given into a vein (IV).

Possible side effects of hypocalcemia

  • Feeling tired
  • Memory loss, feeling confused
  • Being depressed
  • Seizures
  • Muscle spasms
  • Low blood pressure
  • Heart failure
  • Heart rhythm changes
  • Hair loss
  • Certain areas of the skin have more color and are irritated

Hypercalcemia (too much calcium in the blood)

Hypercalcemia can be caused by;

  • Some types of cancer;
  • A parathyroid imbalance; and
  • Taking certain medicines.

Medicines that can cause hypercalcemia include too much vitamin D, thiazides, or calcium supplements.

To decrease calcium in the blood, staff members can give the patient large amounts of IV fluids with diuretics (water pills). If the hypercalcemia is severe, the patient may receive calcitonin, pamidronate, or zolendronic acid.

Possible side effects of hypercalcemia

  • Loss of appetite
  • Nausea or vomiting
  • Constipation
  • Decreased kidney function
  • Change in heart rhythms

Special instructions for calcium

  • Some antacids contain calcium (Mylanta®, Rolaids®, Tums®). Be careful in taking these if you have kidney problems or if you are already taking another form of calcium.
  • Store all tablets and liquid at room temperature in a dry place.
  • Please talk to the doctor or nurse if you think you are having symptoms of hypocalcemia or hypercalcemia. If you are in the local area, call 901-595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).