Hypercalcemia: what is it, symptoms, causes, treatments

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

Written by Kristin DeJohn 

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

Written by Kristin DeJohn 

last updated: Oct 22, 2021

4 min read

You may have heard the term “electrolyte imbalance.” Electrolytes are essential minerals that control everyday functions like your heartbeat, breathing, or flexing a muscle. Calcium is one of those essential minerals, and when your calcium levels are above or below normal, you develop an electrolyte imbalance (Shrimanker, 2021; Catalano, 2018).

Every move you make requires calcium, but too little (hypocalcemia) or too much (hypercalcemia) calcium can cause serious health problems. So, it’s important to know the science behind why a calcium balance is critical and what symptoms to watch out for if your calcium levels dip below or rise above normal (Catalano, 2018).

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What is hypercalcemia?

Hypercalcemia occurs when too much calcium enters the bloodstream. It’s pretty common, affecting up to 2% of the population. The calcium can come from places like the bones and kidneys or from too much in the diet. Hypercalcemia falls into three categories depending on how much calcium is in the blood (Sadiq, 2021):

  • Mild hypercalcemia: 10.5 to 11.9 mg/dL

  • Moderate hypercalcemia: 12.0 to 13.9 mg/dL

  • Severe hypercalcemia: > 14.0 mg/dL

Mild hypercalcemia may not have symptoms. At the other extreme, a hypercalcemic crisis is a life-threatening medical emergency (Carrick, 2018). Over time, too much calcium in the blood can create kidney stones, weaken the bones, and damage other organs like the heart and brain (Sadiq, 2021). 

Hypercalcemia symptoms

Symptoms of hypercalcemia usually don’t show until calcium levels are higher than 12 mg/dl. The earliest symptoms may include (Sadiq, 2021; Catalano, 2018):

  • Nausea/vomiting

  • Abdominal pain

  • Loss of appetite

  • Frequent urination

  • Feeling thirsty/dehydrated

  • Constipation

Severe hypercalcemia can lead to additional symptoms like:

  • Muscle weakness and bone pain

  • Memory loss and confusion

  • Altered mental status/irritability

  • Fatigue/lethargy

  • Abnormal heart rhythms

  • Trouble walking

What causes hypercalcemia?

There are a variety of causes for high calcium levels in the blood: 


Primary hyperparathyroidism (PHPT) is the most common cause of hypercalcemia. There are four parathyroid glands in the neck that control calcium levels in the body. Their job is to boost calcium in the blood when levels are low by sending out parathyroid hormone. This hormone triggers bones to release calcium, the kidneys to retain it, and it works with vitamin D to make sure the intestines absorb more calcium (Catalano, 2018).  

PHPT throws the system off. Usually, a noncancerous tumor (adenoma) of one or more of the glands causes PHPT. The benign growth triggers the release of extra parathyroid hormone, which leads to too much calcium entering the bloodstream. PHPT is more common in older people and is three times more likely to affect women (Sadiq, 2021; Yeh, 2013). 

Rarely, parathyroid carcinoma can cause hyperparathyroidism and hypercalcemia (Wolfe, 2021). Other endocrine disorders, such as hypothyroidism and hypoadrenalism (Addison’s disease) can also elevate calcium levels (Omotosho, 2021). 


About 20% of cancerous tumors release large amounts of a protein that, like parathyroid hormone, boosts the calcium level in the blood. If cancer spreads to the bones, it can also trigger the release of calcium by breaking down bone. Solid tumors like lung cancer and breast cancer, and blood cancers like lymphoma and multiple myeloma, are known causes of hypercalcemia (Vakiti, 2021; Abdalhadi, 2020). 

Too much calcium or vitamin D

Taking too much calcium or vitamin D in the form of antacids or supplements can also lead to hypercalcemia. Vitamin D boosts calcium absorption. So, it’s a great combination if you are calcium or vitamin D deficient. But, too much can cause toxicity by overloading the system (Machado, 2015; Catalano, 2018). 

Some medications

A variety of medications can cause hypercalcemia. These include thiazide diuretics (water pills), lithium (used to treat bipolar disorder), vitamins A & K, and theophylline (used to treat COPD and asthma). It’s best to check with your healthcare provider about medications and their impact on electrolytes and bones (Tebben, 2016). 

Hereditary factors

Familial hypocalciuric hypercalcemia—a rare genetic disorder—causes very high calcium levels. It usually does not cause symptoms, and the high levels typically aren’t high enough to cause major problems (Afzal, 2021). 

Severe dehydration

Having less fluid in your blood causes a rise in calcium. Dehydration can lead to mild or transient hypercalcemia. It’s rare, but extreme dehydration can lead to hospitalization for hypercalcemia (Acharya, 2021; Fernandes, 2015).

Long-term immobility and bone disorders

When bones don’t bear weight for long periods, they can weaken and lose calcium. If someone is in bed for long periods, the bones may begin to leak calcium into the blood (Tebben, 2016; Omotosho, 2021).

People with bone diseases like Paget’s disease also have chronic problems with calcium draining from the bones. This can cause calcium levels to rise, especially if the person is bedridden or dehydrated (Charles, 2021; Tebben, 2016). 

Diagnosing hypercalcemia

Your healthcare provider might spot high calcium levels during a routine physical when they check your blood work. It helps to alert them of any supplements you are taking. Blood tests can tell them how high your parathyroid hormone levels are, along with Vitamin D, calcium, and other markers (Sadiq, 2021).

If your healthcare provider thinks something is affecting the parathyroid glands in your neck, an ultrasound or MRI can help clarify what’s going on. They may also check your thyroid gland. CT scans or mammograms may also play a role in ruling out potential tumors. An ECG is also used to check to see if the calcium is affecting your heart rate. (Sadiq, 2021).

In the case of severe hypercalcemia, immediate treatment will be the priority to balance out calcium levels, and a full workup will follow (Sadiq, 2021).

Treating hypercalcemia

Having mild-to-moderate amounts of calcium in the blood is a fairly common condition and usually isn’t an emergency and often doesn’t need immediate treatment. Cancer-related hypercalcemia with high blood levels of calcium poses the highest risk for needing emergency medical attention (Wagner, 2017).

Whether a healthcare provider treats hypercalcemia or not depends on the cause and your blood calcium levels. The following are common approaches depending on the diagnosis (Sadiq, 2021; Carrick, 2018; Omotosho, 2021):

  • Drinking plenty of fluids may reverse mild hypercalcemia

  • The body may need intravenous fluids (saline) to balance high levels quickly

  • Reducing dietary calcium  

  • Discontinuing calcium and vitamin D supplements (Tebben, 2016)

  • Dialysis may be necessary to remove calcium from the blood in severe cases

  • Surgery to remove an enlarged parathyroid gland usually cures hypercalcemia

  • Treatments to strengthen weakened bones may be necessary

  • Hypercalcemia of malignancy (cancer) requires ongoing management

When to call a doctor

If you develop symptoms of hypercalcemia, such as extreme thirst, frequent urination, or abdominal pain, it’s best to contact a healthcare provider right away, and they can advise you of the steps to take based on your symptoms and medical history.

Catching hypercalcemia early and correcting the imbalance offers the best outcomes. In some cases, it’s a medical emergency. In milder cases, you may need plenty of fluids and a check-up from your healthcare provider to figure out what’s causing it.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

October 22, 2021

Written by

Kristin DeJohn

Fact checked by

Felix Gussone, MD

About the medical reviewer

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.