Hypercalcemia Causes

Hypercalcemia is a condition in which you have too much calcium in your blood. Calcium performs important functions, such as helping to keep your bones healthy.

However, too much of it can cause problems. Hypercalcemia makes it hard for calcium to do its job.

Hypercalcemia is fairly rare. It occurs in less than one percent of people, according to the National Institutes of Health (NIH).

What Causes Hypercalcemia?

Your body manages the calcium level in your blood through parathyroid hormone (PTH) and another hormone called calcitonin. Normally, PTH increases when the level of calcium in your blood falls and decreases when your calcium level rises.

Your body also makes calcitonin when your calcium level gets too high. When you have hypercalcemia, your body is unable to regulate your calcium level as it normally would. There are several possible causes of this condition.


Parathyroid glands (four small glands) are located near the thyroid gland in the neck and regulate parathyroid hormone which in turn regulates calcium in the blood.

When at least one of your parathyroid glands becomes overly active, the condition is called hyperparathyroidism.

This is the leading cause of hypercalcemia, especially in women over 50 years old. It occurs when the glands release too much PTH.

Lung Diseases and Cancers

Granulomatous diseases, such as tuberculosis, are lung diseases that can cause your vitamin D levels to rise. This causes more calcium absorption, which increases the calcium level in your blood.

Some cancers, especially lung cancer, breast cancer, and blood cancers, can raise your risk for hypercalcemia.

Medication Side Effects

Some types of drugs, such as thiazide diuretics, can cause hypercalcemia because less calcium is excreted and more retained in the body. Other drugs, such as lithium, cause more PTH to be released.

Dietary Supplements

Taking too much vitamin D or calcium in the form of supplements can raise your calcium level.


This usually leads to mild cases of hypercalcemia. When you’re dehydrated, your calcium level rises due to the low amount of fluid you have in your blood.

Symptoms and Diagnosis

Hypercalcemia often causes no symptoms. The earliest symptoms 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.

Very severe hypercalcemia often causes brain dysfunction with confusion, emotional disturbances, delirium, hallucinations, and coma.
Muscle weakness may occur, and abnormal heart rhythms and death can follow. Long-term or severe hypercalcemia commonly results in kidney stones containing calcium.

Less commonly, kidney failure develops, but it usually resolves with treatment. However, if enough calcium accumulates within the kidneys, damage is irreversible.

Hypercalcemia is usually detected during routine blood tests.


If 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 intravenously as long as kidney function is normal.

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

Hypercalcemia caused by cancer is particularly difficult to treat. If the cancer cannot be controlled, hypercalcemia usually returns despite the best treatment.

Source & More Info: Merck Manuals and Healthline



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