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What is hypercalcemia?

Hypercalcemia is an abnormally high amount of calcium in the blood and can be present with a number of symptoms depending on the area of the body that's affected and the severity of the effects. Calcium is needed by the body to function properly. Calcium can affect nerves, muscles, digestive tract, kidneys and the function of the heart. When the calcium level becomes too high, unusual symptoms may develop. This may occur if cancer has spread to the bones, causing calcium to be released, or cancer may release certain hormones that affect the normal systems that control the calcium level in the blood.

Hypercalcemia plays a direct role in nerve function, renal function (kidneys), muscle contraction (including the contraction and conductivity in the heart muscle) and the function of the digestive system. Due to its role in the normal function of vital body systems, it needs to be carefully regulated.


When calcium levels become too high, unusual symptoms may develop. These symptoms are sometimes mistaken for other issues such as common fatigue and illness. A basic metabolic panel or blood panel will show doctors important information relating to kidney function, blood sugar, electrolyte and acid/base balance including calcium levels.

Common symptoms of hypercalcemia include:

  • Fatigue (tired feeling)
  • Excessive sleepiness
  • Confusion
  • Coma
  • Extreme muscle weakness
  • Loss of appetite
  • Nausea, vomiting
  • Stomach pain
  • Constipation
  • Changes in heartbeat (too slow or too fast)
  • Frequent urination
  • Excessive thirst
  • Dry mucous membranes (the lining of the mouth and throat)


Primary hyperparathyroidism is one of the more common causes of hypercalcemia. This occurs due to excess PTH released from an enlargement of one or more of the parathyroid glands, or a growth (usually not cancer) on one of the glands.

Other causes of hypercalcemia include:

  • Adrenal gland failure
  • Being bedbound for a long period of time
  • Excess of calcium in the diet
  • An inherited condition that affects the body’s ability to regulate calcium
  • Hyperthyroidism
  • Kidney failure
  • Certain medications such as lithium and thiazide diuretics
  • Vitamin D excess from diet or inflammatory diseases
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