Hypercalcemia Complications: what nurses need to know

Published: May 7, 2023

Last Updated: May 14, 2023

William Kelly, MSN, FNP-C

Author | Nurse Practitioner

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An image of IV magnesium sulfate with Magnesium in a ball with low levels with surrounding foods that are high in magnesium

Hypercalcemia is when the blood has high calcium levels, which can lead to deadly hypercalcemia complications. These complications can be severe and potentially life-threatening if not identified and managed promptly.

As healthcare professionals who may have to care for patients with hypercalcemia, nurses need to be aware of the potential complications associated with this condition.

In this article, we will discuss levels of hypercalcemia, causes, treatment, complications, and monitoring parameters that nurses need to know about.

Hypercalcemia: Nursing assessment, complications, and treatment, with image of blood vessel with high level of calcium

Normal Calcium Levels & Hypercalcemia

Normal calcium levels can range from 8.5 – 10.5 mg/dL.

Calcium Levels

  • Normal Levels: 8.5 – 10.5 mg/dL
  • Mild Hypercalcemia: 10.5 – 12 mg/dL
  • Moderate Hypercalcemia: 12 – 14 mg/dL
  • Severe Hypercalcemia: > 14 mg/dL
  • Ionized Hypercalcemia: > 5.4 mg/dL

Causes Of Hypocalcemia:

There are multiple causes of hypercalcemia, including:

An image of the thyroid and parathyroid glands

Primary Hyperparathyroidism

Primary hyperparathyroidism is the most common cause of hypercalcemia, accounting for about 80% of cases. It occurs when the parathyroid glands produce too much parathyroid hormone (PTH), increasing calcium levels in the blood.

The most common cause of this is a benign tumor called a parathyroid adenoma, which develops in one of the parathyroid glands. Other less common causes of primary hyperparathyroidism include parathyroid hyperplasia, parathyroid cancer, and inherited genetic disorders.

Vitamin D in a softgel


Some types of cancer, such as multiple myeloma, lung cancer, breast cancer, and kidney cancer, can cause hypercalcemia by releasing substances that increase calcium levels in the blood. 

A yellow sun with vitamin D in the middle

Excessive Vitamin D

Taking too much vitamin D supplements or having a disease that increases vitamin D levels in the body, such as sarcoidosis, can lead to hypercalcemia.

A vector graphic of a bed


Prolonged immobilization, such as when a patient is bed-bound, can cause hypercalcemia by increasing bone resorption and calcium release.

A bottle of medications that are prescription


Certain medications can cause high calcium levels, including:

  • Certain supplements in excess (Vitamin D, Calcium, Vitamin A)
  • Thiazide diuretics
  • Lithium
  • Theophylline toxicity
A strand of DNA

Other conditions

Other generic and acquired positions can lead to hypercalcemia complications, including hyperthyroidism, acromegaly, pheochromocytoma, adrenal insufficiency, and TPN.

The causes of hypercalcemia explained

Nursing Assessment Of Hypercalcemia


Hypercalcemia can cause a wide range of symptoms, most nonspecific. The severity and type of symptoms depend on the calcium level in the blood, the underlying cause of hypercalcemia, and how quickly the levels change.

  • Mild Hypercalcemia (10.5 – 12 mg/dL): Usually asymptoamtic
  • Moderate hypercalcemia (12 – 14 mg/dL): polyuria, polydipsia, anorexia, nausea, and constipation
  • Severe Hypercalcemia (> 14 mg/dL): worsened above symptoms, altered mental status, and even cardiac arrhythmias.

Common symptoms of hypercalcemia include:

A depiction of the small bowel, which is largely responsible for absorption of magnesium

GI side effects

Hypercalcemia can cause anorexia, constipation, nausea, and vomiting.

A battery symbol which is low

Weakness and Fatigue

Patients with hypercalcemia often feel tired and weak, just like with many other electrolyte abnormalities.

A bladder full of urine

Urinary Frequency

High calcium levels lead to decreased concentration ability of the kidneys and subsequent urinary frequency/dehydration. 

a picture of a bladder with bladder stone blocking the bladder neck

Kidney Stones

Chronic high calcium levels in the urine can lead to nephrolithiasis (kidney stones). 

graphic of a brain

Altered Mental Status

Hypercalcemia can affect the central nervous system, leading to cognitive impairment and even confusion, stupor, or coma.

a desaturated heart and yellow cardiac conductive tissue showing the SA node, AV node, and ventricles

S/S of arrhythmias

Hypercalcemia can affect the heart’s electrical conductivity, leading to arrhythmias, which may cause palpitations, chest pain, shortness of breath, dizziness, or syncope. This is generally not as common with hypercalcemia as with other electrolyte abnormalities. 

An illustration of the heart with the pulmonary and aortic vessels

Cardiac Calcifications

Chronic hypercalcemia can lead to the deposition of calcium in heart valves, coronary arteries, and the heart muscle itself. This can also lead to hypertension and heart failure. 

A muscle with red electric bolts indicating pain

Bone Pain

Bone pain can be a symptom of high calcium due to malignancy or primary hyperparathyroidism. 

PHYSICAL Assessment

When performing a physical exam for a patient suspected of having hypercalcemia, the nurse should assess for the following:

Vital Signs

  • HR: May be irregular (indicating an arrhythmia)
  • BP: May be increased
A face with the facial nerve present, which is causing Chvostek sign


  • General: May appear weak or fatigued
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  • Heart: May be irregular if arrhythmia present
  • Lungs: Clear to auscultation
a gloved hand palpating unspecified skin


  • Abdomen: May have abdominal tenderness
  • Extremities: May have bone pain or tenderness, may have extremity weakness

Treatment for Hypercalcemia

The treatment of hypercalcemia depends on the severity of the condition and the underlying cause.

Assess the Patient

Ensure they don’t have any symptoms and are stable, including recent vital signs.

Cardiac Monitor

Make sure your patient is on the cardiac monitor. Obtain an ECG if it still needs to be done. 

Notify the Provider

Notify the provider of the calcium levels, your assessment, and their cardiac rhythm.

Ensure IV access

Make sure there is at least one IV site, but place a second line if the hypercalcemia is severe.

Administer Treatment

Administer medications and fluids that are ordered (discussed below).

Treatment for hypercalcemia:

An IV drip chamber with 1 drop (ggt) of fluid dripping down

General Measures

Mild hypercalcemia often does not require any specific calcium-lowering therapies, but instead can usually be managed by:

  • Treating any dehydration
  • Decreasing bed rest
  • Avoiding high-calcium diets
  • Avoiding medications that increase calcium levels
    • Thiazide Diuretics
    • Lithium 
    • Calcium supplements
    • Vitamin D supplements
Bag of IV magnesium sulfate

Isotonic Fluids

Patients who have moderate to severe hypercalcemia often are volume depleted. This helps to correct the hypovolemia and increase calciume excretion in the urine. 

NS or LR given at 200-300ml/hr and then adjusted to a urine output of 100-150ml/hr is recommended for 24-48 hours until the volume depletion is corrected. 

What about Lasix?

Loop diuretics aren’t traditionally recommended, however, patients with heart or kidney failure may benefit/require loop diuretics in addition to fluid.



Calcitonin is a hormone that can lower calcium levels in the blood by decreasing bone resorption. This is usually reserved for severe hypercalcemia with neurologic symptoms like decreased mental status. 

The recommended dose is 4 units/kg SQ or IM every 12 hours for 24-48 hours. 

Vitamin D softgels


These medications can reduce bone resorption and lower calcium levels in the blood. Bisphosphonates are used for longer-term control of hypercalcemia, especially when related to malignancy. 

If given IV for severe hypercalcemia in the hospital, Zalendronic acid is recommended 4mg IV over 15 minutes. This can be repeated in 7 days if needed.

Vitamin D softgels

Denosumab (prolia)

Denosumab is a monoclonal antibody that is sometimes used if Bisphosphonates are not effective or not able to be used. There is a higher risk of hypocalcemia occurring with this medication, so it is avoided when possible.

Bag of IV magnesium sulfate


This is primarily only given if the hypercalcemia is caused by lymphoma, sarcoidosis, or other granulomatous disease that increases calcitriol production and subsequently increases calcium absorption. 

Bag of IV magnesium sulfate


In severe cases, dialysis may be needed to remove excess calcium from the blood, especially if they also have heart failure or severe renal failure.

Bag of IV magnesium sulfate

Treat underlying conditions

Underlying conditions, such as cancer, may need to be treated to improve calcium levels.

Monitoring of Hypercalcemia Complications

As a nurse, it is essential to monitor patients with hypercalcemia closely to identify and manage any potential complications. The following parameters should be observed:

A Gold top blood vial filled with blood

Serum Calcium Levels

Serum calcium levels should be monitored regularly to assess treatment response and to identify potential complications such as hypocalcemia.

An image of the thyroid and parathyroid glands

Serum PTH levels

Measuring parathyroid hormone helps determine the etiology of the high calcium levels. If PTH is elevated, this points to primary hyperparathyroidism. If it is low, is is likely not from hyperparathyroidism.

A Gold top blood vial filled with blood

Other Labs

The nurse should monitor laboratory values such as serum calcium, magnesium, and phosphate levels and liver and kidney function tests to assess for complications and monitor treatment progress.

A Gold top blood vial filled with blood

ECG monitoring

Possible hypercalcemia complications include arrhythmias, so continuous telemetry monitoring, as well as occasional 12-lead ECGs are indicated.


Patients with severe hypercalcemia that warrants significant calcium-reducing therapies should have a nephrology consult on board!

Hypercalcemia and Cardiac Arrhythmias

Hypercalcemia can cause a variety of ECG changes, including:

  • ST-Segment: Elevation can occur, especially in the inferior leads (II, III, aVF), and can be shortened as well.
  • QT interval: Shortened, which can increase the risk of arrhythmias like VTACH
  • T-waves: Biphasic or widened
  • Other: J waves (osborn waves), which are typically associated with hypothermia, but severe hypercalcemia can mimic this. 

Arrhythmias are less common with hypercalcemia than with other electrolyte abnormalities but still can cause them including:

  • Atrial fibrillation (AFib): Hypercalcemia can cause AFib, a rapid and irregular heart rhythm caused by abnormal electrical activity in the atria.
  • Ventricular fibrillation (VFib): In rare cases, hypercalcemia can cause VFib, a potentially life-threatening arrhythmia that occurs when the ventricles quiver instead of contracting.
  • Ventricular Tachycardia
  • AV Blocks

These ECG changes are thought to be due to altered myocardial repolarization caused by hypercalcemia. 

Hypercalcemia is associated with ST-segment elevation and shortening, QT-interval shortening, Biphasic or widened T waves, and J waves (osborn waves)

Want to learn more?

If you want to learn more, I have a complete video course “ECG Rhythm Master”, made specifically for nurses which goes into so much more depth and detail.

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  • Identify all cardiac rhythms inside and out
  • Understand the pathophysiology of why and how arrhythmias occur
  • Learn how to manage arrhythmias like an expert nurse
  • Become proficient with emergency procedures like transcutaneous pacing, defibrillation, synchronized shock, and more!

I also include some great free bonuses with the course, including:

  • ECG Rhythm Guide eBook (190 pages!)
  • Code Cart Med Guide (code cart medication guide)
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Check out more about the course here!

In conclusion, hypercalcemia is a potentially serious condition that requires prompt diagnosis and treatment to prevent complications.

As a nurse, it is important to be aware of the causes, symptoms, and ECG changes associated with hypercalcemia, as well as the monitoring and treatment options available. By taking a proactive approach to monitoring and managing patients with hypercalcemia, nurses can help improve outcomes and prevent serious complications. 

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