Calcitonin
Calcitonin is a protein hormone produced naturally by the thyroid gland, which plays a vital role in regulating calcium and phosphorus levels in the bloodstream. It helps maintain bone density and strength, and is particularly important for individuals who may be at risk for bone-related conditions, such as osteoporosis, Paget's disease, and hypercalcemia, where there is an excess of calcium in the blood. In cases where the body does not produce sufficient calcitonin, synthetic versions of the hormone, such as calcitonin-salmon, can be prescribed. These are available in both injectable forms and nasal sprays.
While synthetic calcitonin has been beneficial in treating certain conditions, there have been concerns about its safety, particularly regarding potential links to cancer. Regulatory agencies in Europe and Canada have advised against its routine use for osteoporosis, suggesting it should be reserved for specific conditions like Paget's disease or temporary immobilization. Conversely, the U.S. FDA has not found conclusive evidence linking calcitonin to cancer, allowing its continued availability. As with any medication, it is essential for patients to discuss the risks and benefits with their healthcare providers to tailor treatment to individual needs.
Calcitonin
Calcitonin (pronounced kal-sih-TOE-nin) is both a protein hormone naturally produced by the body, and a synthetic prescription drug. As a natural hormone in the body, calcitonin serves to regulate the level of calcium and phosphorous in the bloodstream. Synthetic calcitonin is a prescription medication used to supplement calcitonin levels when an individual does not produce enough calcitonin naturally.
How Calcitonin Works
Calcitonin is important to the regulation of calcium in the blood, increasing or decreasing it to maintain normal levels. In mammals such as humans, calcitonin is produced mostly by cells in the thyroid gland and is sometimes called thyrocalcitonin. Non-mammals such as birds and fish also produce calcitonin, but in an organ known as the ultimobranchial body.
Calcium is necessary for bone strength. Without it, bones can become brittle and break. Calcium levels can be especially important for pregnant women; individuals with medical conditions that cause limited mobility; postmenopausal women; and people with bone-related medical conditions such as Paget's disease, which causes painful deformations of the bones.
Scientists first isolated human calcitonin for study in 1962. During this research, they determined that calcitonin plays a key role in the regulation of parathyroid hormone. Parathyroid hormone encourages bones to give up their calcium, while calcitonin helps prevent this loss.
Calcitonin works on various systems of the body to regulate the levels of calcium and phosphorus in the blood to promote and maintain healthy bone growth. Calcitonin controls the amount of calcium absorbed by the intestines after meals; encourages vitamin D production in the kidneys to support the body's use of available calcium; and binds to osteoclasts, cells that dissolve bones, preventing them from destroying bone tissue.
Synthetic Calcitonin
As understanding grew of the function of calcitonin in bone health, researchers looked for ways to supplement this natural hormone by synthesizing substances from outside the human body. Salmon calcitonin was found to be the most potent. By the 1970s, injectable or infusible forms of calcitonin were approved in Europe. These early versions required the drug to be injected or dripped into a vein for administration. Synthetic calcitonin became available in the United States in 1986. Around the same time, aerosolized nasal spray formulations became available in Europe; the US markets followed in 1995.
Calcitonin is marketed under various names, including Apo-Calcitonin, Calcimar, Caltine, Fortical, Miacalcin, Miacalcin Nasal, and calcitonin-salmon.
Calcitonin may be prescribed to combat the bone-weakening effects of osteoporosis in postmenopausal women, to treat Paget's disease, and to treat hypercalcemia, a condition in which the bloodstream contains too much calcium. Off-label use, which is not approved by the US Food and Drug Administration (FDA), includes the treatment of secondary osteoporosis, a condition in which bone weakening occurs because of another condition, such as a hormonal imbalance, or as a side effect of a drug.
Side Effects and Concerns
As a protein, synthetic calcitonin has the potential to cause severe allergic reactions, including shock, breathing difficulties, wheezing, and swelling of the throat or tongue. This is especially true for those who have an allergy to salmon. Other side effects of synthetic calcitonin include back or joint pain, headaches, and nasal problems such as crusting, dryness, redness, irritation, sores, itching, infection, runny or blocked nose, and nosebleeds.
During the early 2000s, concerns arose about the safety of the use of salmon-derived calcitonin. European medical authorities began investigating possible links between calcitonin use and prostate cancer. Officials in other parts of the world, including the United States, also began looking into possible connections between synthesized calcitonin and various forms of cancer.
In 2012 the European Medicines Agency (EMA) recommended that calcitonin no longer be prescribed as a routine treatment for osteoporosis. However, the EMA recommended its continued use for the treatment of Paget's disease and for patients who are temporarily immobilized due to fracture, heart attack, or another condition. According to the EMA, since the duration of treatment for these conditions is short—four to twelve weeks—the risk of developing cancer is minimal. The EMA also allowed the drug to remain available for treatment of chronic excessive calcium levels (hypercalcemia) caused by cancer treatment. Canadian health officials followed the EMA and implemented these recommendations in 2013.
Not all medical experts agreed with the restrictions, however, noting that the increased risk of cancer is small and does not outweigh the benefits of the drug on individuals dealing with easily fractured bones. In the United States, the FDA determined that no conclusive evidence linked synthetic calcitonin to cancer. The FDA’s official determination on calcitonin was issued in September 2015 and urged physicians and patients to discuss the risks and benefits of treatment so that individual treatment decisions could be made. The drugs remain available on the US market.
Dosing
Dosing varies by condition and patient and is determined by the administering physician. The usual recommended adult dose for the nasal spray is one spray into the nose per day, alternating nostrils for each dose. Patients should also consult their physician about supplemental dosages of oral calcium and vitamin D.
Calcitonin nasal sprays are not recommended for use by children. They are also not recommended for use by pregnant women or nursing mothers because the potential adverse effects on children have not been adequately studied.
Other Functions of Calcitonin
The body does not normally produce an overabundance of the calcitonin hormone. Thus, the presence of a high calcitonin concentration in the blood can be an indicator of medullary thyroid cancer, which is cancer of the cells that produce calcitonin in the thyroid.
Some research also indicates that calcitonin levels in humans and other mammals may play a role in hunger and satiety, or the feeling of being full and satisfied after a meal.
Bibliography
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"Calcitonin." Saunders Nursing Drug Handbook 2016. Elsevier: St. Louis, MO. 2015. Print. 10 Jan. 2016.
Lowry, Fran. "FDA Panel Says to Stop Marketing Salmon Calcitonin for Osteoporosis." Medscape Medical News. Medscape News & Perspective. 6 March 2013. Web. 10 Jan. 2016.
Mandal, Ananya. "What Is Calcitonin?" News Medical Life Sciences & Medicine. AZO Network. Oct. 2014. Web. 10 Jan. 2016. http://www.news-medical.net/health/What-is-Calcitonin.aspx
"Questions and Answers: Changes in the Indicated Population for Miacalcin (Calcitonin-Salmon). US Food and Drug Administration. US Department of Health and Human Services. Web. 10 Jan. 2016. http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm388641.htm
Robertson, Sally. "Calcitonin Actions." News Medical Life Sciences & Medicine. AZO Network. July 2015. Web. 10 Jan. 2016. http://www.news-medical.net/health/Calcitonin-Actions.aspx