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Hypercalcemia (High Level of Calcium in the Blood)


James L. Lewis III

, MD, Brookwood Baptist Health and Saint Vincent’s Ascension Health, Birmingham

Reviewed/Revised Sep 2023
Topic Resources

In hypercalcemia, the level of calcium in blood is too high.

  • A high calcium level may result from a problem with the parathyroid glands, as well as from diet, cancer, or disorders affecting bone.

  • At first, people have digestive problems, feel thirsty, and may urinate a lot, but if severe, hypercalcemia leads to confusion and eventually coma. If not recognized and treated, the disorder can be life threatening.

  • Usually, hypercalcemia is detected by routine blood tests.

  • Drinking lots of fluids may be sufficient, but diuretics may increase calcium excretion, and medications can be used to slow the release of calcium from bone if needed.

Causes of Hypercalcemia

Causes of hypercalcemia include the following:

Did You Know...

  • Lack of mobility can make the calcium level high because bones weaken and release calcium into the blood.


The parathyroid glands release parathyroid hormone, which

  • Increases the absorption of calcium from the digestive tract

  • Causes the kidneys to excrete less calcium

  • Causes bones to release stored calcium

Parathyroid hormone causes the kidneys to excrete more phosphate, but it also causes the bones to release phosphate into the blood. The balance between these two effects determines whether the phosphate level remains normal or decreases.

If the parathyroid glands release too much parathyroid hormone, hyperparathyroidism results. People with hyperparathyroidism have too much calcium and a normal or low level of phosphate in their blood.

Primary hyperparathyroidism

In primary hyperparathyroidism, an abnormality causes the release of too much parathyroid hormone. In about 90% of people with primary hyperparathyroidism, the abnormality is a noncancerous tumor (adenoma) in one of the parathyroid glands. In the remaining 10%, the glands simply enlarge and produce too much hormone. Rarely, cancers of the parathyroid glands cause hyperparathyroidism.

Primary hyperparathyroidism is more common among women than among men. It is more likely to develop in older adults and in people who have received radiation therapy to the neck. Sometimes it occurs as part of the syndrome of multiple endocrine neoplasia Multiple Endocrine Neoplasia Syndromes , a rare hereditary disorder.

Primary hyperparathyroidism is usually treated by surgically removing one or more of the parathyroid glands. The goal is to remove all parathyroid tissue that is producing excess hormone. Surgery is successful in almost 90% of cases.

Secondary hyperparathyroidism

Tertiary hyperparathyroidism

In tertiary hyperparathyroidism, excess parathyroid hormone is released regardless of the amount of calcium in the blood. Tertiary hyperparathyroidism usually occurs in people who have had long-standing secondary hyperparathyroidism.

Treatment depends on the cause.

Familial hypocalciuric hypercalcemia

The syndrome of familial hypocalciuric hypercalcemia is a hereditary disorder that results from the parathyroid glands underestimating the amount of calcium in the blood and, in response, mistakenly secreting too much parathyroid hormone. Parathyroid surgery is not useful in this disorder, and other treatment is usually not needed.

Symptoms of Hypercalcemia

Hypercalcemia often causes few symptoms. The earliest symptoms of hypercalcemia are usually constipation, nausea, vomiting, abdominal pain, and loss of appetite. People may excrete abnormally large amounts of urine, resulting in dehydration and increased thirst.

Diagnosis of Hypercalcemia

  • Measurement of calcium level in the blood

Hypercalcemia is usually detected during routine blood tests.

Once hypercalcemia is detected, additional testing may be needed to determine the cause. Additional blood tests and urine tests may be done. A chest x-ray may also be needed to look for cancer or a lung disorder that can cause hypercalcemia. Genetic testing may be done when doctors are looking for a hereditary cause.

Treatment of Hypercalcemia

  • Fluids and medications to increase excretion of calcium

When hypercalcemia is not severe, correcting the cause is often sufficient. If people have mild hypercalcemia or conditions that can cause hypercalcemia and if their kidney function is normal, they are usually advised to drink plenty of fluids. Fluids stimulate the kidneys to excrete calcium and help prevent dehydration.

Doctors may advise people to take mineral supplements containing phosphate, which helps prevent calcium absorption.

If the calcium level is very high or if symptoms of brain dysfunction or muscle weakness appear, fluids and diuretics are given by vein (intravenously) as long as kidney function is normal. Dialysis Dialysis Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly. There are a number of reasons... read more Dialysis is a highly effective, safe, reliable treatment, but it is usually used only for people with severe hypercalcemia that cannot be treated by other methods.

Several other medications (including bisphosphonates, calcitonin, corticosteroids, and, rarely, plicamycin) can be used to treat hypercalcemia. These medications work primarily by slowing the release of calcium from bone.

Hypercalcemia caused by cancer is particularly difficult to treat. Sometimes a medication called denosumab is helpful. If the cancer cannot be controlled, hypercalcemia usually returns despite the best treatment.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Calcidol, Calciferol, D3 Vitamin, DECARA, Deltalin, Dialyvite Vitamin D, Dialyvite Vitamin D3, Drisdol, D-Vita, Enfamil D-Vi-Sol, Ergo D, Fiber with Vitamin D3 Gummies Gluten-Free, Happy Sunshine Vitamin D3, MAXIMUM D3, PureMark Naturals Vitamin D, Replesta, Replesta Children's, Super Happy SUNSHINE Vitamin D3, Thera-D 2000, Thera-D 4000, Thera-D Rapid Repletion, THERA-D SPORT, UpSpring Baby Vitamin D, UpSpring Baby Vitamin D3, YumVs, YumVs Kids ZERO, YumVs ZERO
Fortical , Miacalcin
Prolia, XGEVA
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