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Hypercalcemia
(Elevated Calcium Levels)

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Medical Author:

Ruchi Mathur, MD, FRCP(C)

Ruchi Mathur, MD, FRCP(C)

Ruchi Mathur, MD, FRCP(C) is an Attending Physician with the Division of Endocrinology, Diabetes and Metabolism and Associate Director of Clinical Research, Recruitment and Phenotyping with the Center for Androgen Related Disorders, Department of Obstetrics and Gynecology at Cedars-Sinai Medical Center.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Hypercalcemia Introduction

Calcium is a mineral that is important in the regulation and processes of many body functions including bone formation, hormone release, muscle contraction, and nerve and brain function. Hypercalcemia is the term that refers to elevated levels of calcium in the bloodstream.

Regulation of Calcium

Calcium levels are tightly regulated in the body. Calcium regulation is primarily controlled by parathyroid hormone (PTH), vitamin D, and calcitonin.

• Parathyroid hormone is a hormone produced by the parathyroid glands, which are four small glands that surround the thyroid and are found in the anterior part of the lower neck.
  
  
• Vitamin D is obtained through a process that begins with sun exposure to the skin, the process then continues in the liver and kidneys. Vitamin D can also be found in foods such as eggs and dairy products.
  
  
• Calcitonin is produced in specialized cells in the thyroid gland.

Together, these three hormones act on the bones, the kidneys, and the GI tract to regulate calcium levels in the bloodstream.

What are the causes of hypercalcemia?

One of the most common causes of high calcium levels (hypercalcemia), is an overproduction of parathyroid hormone, or hyperparathyroidism.

• Hyperparathyroidism occurs in 25 out of every 100,000 persons and tends to be more common in women.
  
  
• It can be the result of all four parathyroid glands producing too much PTH (parathyroid hyperplasia), or one gland specifically producing an excessive amount of hormone (usually the result of a parathyroid adenoma, or benign tumor).

Hypercalcemia can occur due to other medical conditions. These conditions can vary in severity and chronicity, and may be life-threatening. Malignancy is a common cause of elevated blood calcium. Up to 20% of individuals with cancer will develop hypercalcemia at some point in their disease.

Other conditions associated with hypercalcemia include:

• Cancers, especially lung cancer and breast cancer
  
  
• Immobilization over a long period of time
  
  
• Kidney failure
  
  
• Overactive thyroid (hyperthyroidism) or excessive thyroid hormone intake
  
  
• Use of certain medications such as the thiazide diuretics
  
  
• Inherited kidney or metabolic conditions
  
  
• Excessive vitamin D levels from vitamins, excessive dietary calcium, or from diseases that may result in excess vitamin D production