Calcitonin: Function, Uses & Side Effects

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Calcitonin is a thyroid hormone that helps maintain calcium homeostasis. That means it regulates your blood calcium levels. Abnormal calcitonin levels may have no direct negative side effects, but may indicate an underlying condition that needs to be addressed, such as hypothyroidism or thyroid cancer.

Salmon calcitonin may be used as a treatment for bone conditions such as postmenopausal osteoporosis.

Below, we’ll briefly discuss what calcitonin is, why it’s important, how to determine abnormal levels, testing, supplements, and steps you can take to optimize your calcitonin levels.

If you’re concerned about your thyroid hormone levels, PrimeHealth Denver specializes in thyroid conditions. Our expert clinicians have helped hundreds of people like you take control of their thyroid health. Schedule your free consultation today!

What is calcitonin?

Calcitonin is a 32-amino acid peptide hormone formed by the C-cells of the thyroid gland (parafollicular cells). Calcitonin regulates blood calcium levels, as well as phosphate levels. When the amount of calcium in your blood is too high, calcitonin helps lower it.

Also called thyrocalcitonin, calcitonin (CT) does the opposite action of the parathyroid hormone (PTH), which increases the calcium levels in your blood.

Read more about the thyroid gland and thyroid disorders: Hypothyroidism: Symptoms & Reversal

The thyroid is a small, butterfly-shaped gland located at the front of the neck. As part of the endocrine system, it maintains many vital functions in the body by producing certain hormones, which are messenger chemicals that regulate different functions of the body.

Healthcare providers and researchers don’t completely understand calcitonin’s importance. Since abnormal calcitonin levels cause few or no adverse events, scientists are confused as to why humans have calcitonin.

However, salmon calcitonin is used as a secondary treatment for bone conditions like Paget’s disease of bone or postmenopausal osteoporosis — after primary treatments such as bisphosphonates fail.

Is calcitonin a parathyroid hormone? No, calcitonin is a hormone produced in the thyroid, which is different from the parathyroid. Calcitonin’s function is actually the opposite of parathyroid hormone — decreasing blood calcium concentration instead of raising it .

What does the calcitonin gene-related peptide do? The calcitonin gene-related peptide (CGRP) is a vasodilator produced in the nervous system. It mainly impacts the cardiovascular system and inflammation response.

Calcitonin & Calcium

What is the primary function of calcitonin? Calcitonin’s primary function is lowering blood calcium levels in 2 ways:

  • Calcitonin blocks osteoclast activity. Osteoclast cells break down bone, which releases calcium from your bone into your blood. Calcitonin’s temporary inhibition of osteoclasts reduces calcium entering your bloodstream.
  • Calcitonin reduces how much calcium your kidneys reabsorb and release into your blood.

Counterintuitively, abnormal CT levels don’t seem to result in abnormal calcium levels.

Calcitonin vs. Parathyroid Hormone

Calcitonin and parathyroid hormone (PTH) are both hormones that regulate blood calcium levels, but in opposite ways.

  • CT decreases blood calcium levels, but it’s less important than PTH. Abnormal PTH levels may result in hypercalcemia (high blood calcium levels) or hypocalcemia (low blood calcium levels). Presently, there are very few  health implications associated with  abnormal calcitonin levels.
  • PTH seems to play a more important role in calcium regulation than calcitonin. The parathyroid glands secrete PTH to increase calcium levels in your bloodstream. PTH also regulates phosphorus and vitamin D levels in your blood and bones.

Calcitonin vs. Calcitriol

Calcitonin and calcitriol both affect calcium levels. However, these two similar-sounding hormones have opposite functions.

  • Calcitonin decreases blood calcium levels by preventing bone calcium from transferring into the bloodstream (bone resorption) and blocks reabsorption of calcium by your kidneys.
  • Calcitriol (active vitamin D) increases the amount of calcium your gut can absorb from food. Calcitriol helps maintain healthy calcium concentration in the kidneys, too.

Parathyroid hormone stimulates the transformation of vitamin D in your body into calcitriol.

Normal Levels of Calcitonin

Normal levels of calcitonin differ depending on your sex:

  • Females: 0 to 5.1 pg/mL
  • Males: 0 to 8.5 pg/mL

(pg/mL stands for “picograms per milliliter.” A picogram is one-trillionth of a gram.)

Some sources say that anything under 10.0 pg/mL should be considered a normal range for calcitonin levels.

High Calcitonin Levels

Having high calcitonin levels doesn’t seem to impact your health negatively.

This contrasts with parathyroid hormone, which also regulates blood calcium levels but can affect your body if levels get too high.

However, high calcitonin may be a sign of 2 rare conditions:

  • Medullary thyroid cancer (MTC): This rare thyroid cancer originates in the thyroid’s C-cells, which are responsible for CT secretion. Medullary thyroid cancer (or carcinoma) may cause C-cells to make excess CT. Though high CT does not impact your health, MTC is very serious. This cancer often spreads to other sites or metastasizes. (MTC is more likely in people with multiple endocrine neoplasia (type 2a or 2b), a genetic condition.)
  • C-cell hyperplasia: This benign (non-cancerous) condition results in accelerated C-cell growth in the thyroid gland, producing excess CT. C-cell hyperplasia may progress to medullary thyroid cancer, which can be deadly.

Higher-than-normal calcitonin levels may occur in people who smoke, have kidney disease, or experience higher body weight. CT may increase when taking medication to stop stomach acid production.

If you’re experiencing warning signs of either MTC or C-cell hyperplasia, such as a lump in the throat or trouble swallowing, ask your healthcare provider about a calcitonin test. Identifying high CT is part of diagnosing or ruling out these serious conditions.

Low Calcitonin Levels

There doesn’t seem to be any impact on your body if you have low calcitonin levels.

This older study concludes that low CT levels may indicate primary hypothyroidism.

People who have had their thyroid removed and therefore have undetectable calcitonin levels show no adverse effects related to blood calcium levels. This contrasts with parathyroid hormone, which also regulates calcium levels but can impact your health if levels become too low.

Alternately, people who have had their thyroid removed do often require synthetic or desiccated thyroid hormone.

Calcitonin Testing

Your doctor can measure your serum calcitonin levels with a blood sample.

Abnormal levels of CT don’t directly impact your health, so doctors typically order a CT test for these reasons:

  • To help diagnose or rule out C-cell hyperplasia
  • To help diagnose or rule out medullary thyroid carcinoma (MTC)
  • To help diagnose or rule out autoimmune thyroid disease
  • To help diagnose or rule out certain cancers, such as lung or pancreatic
  • To monitor the treatment of MTC
  • If you have a family history of a genetic condition called multiple endocrine neoplasia type 2a or 2b, which is associated with developing endocrine tumors, including MTC

Calcitonin as Medicine

Calcitonin is not meant to treat low calcitonin levels since there seem to be no adverse effects of low calcitonin.

However, salmon calcitonin is a treatment for multiple bone conditions:

  • Paget’s disease of bone
  • Postmenopausal osteoporosis
  • Hypercalcemia
  • Bone pain
  • Prevention of bone loss due to sudden immobility

Calcitonin nasal spray is the most common form of salmon calcitonin (an analog of human calcitonin) prescribed to treat these bone conditions. This is usually after primary treatments like bisphosphonate have failed. If nasal symptoms become uncomfortable, your doctor may switch you to calcitonin injections.

Nasal calcitonin doesn’t seem to be effective against hypercalcemia. Injections are the preferred method in that case.

Ask your healthcare provider about prescribing calcitonin.

Possible Side Effects

The most common method of salmon calcitonin delivery is a nasal spray. Here are the possible side effects of nasal calcitonin:

  • Nose bleeding
  • Nasal inflammation
  • Ulcer in the nose
  • Intestinal discomfort
  • Decrease of lithium levels in the bloodstream

The possibility of these side effects increases with age.

If you’re allergic to fish, salmon calcitonin may cause these side effects:

  • Anaphylactic shock
  • Bronchospasm
  • Tongue swelling
  • Rash

Pregnant women who take calcitonin have not experienced any adverse effects, but calcitonin’s efficacy seems to wane quickly (sometimes within 48 hours).

PrimeHealth is Here to Help

Calcitonin is helpful in 2 main ways:

  • Abnormal calcitonin levels may help indicate underlying health problems in your thyroid.
  • Prescription calcitonin may treat bone conditions that are impacting your quality of life.
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PrimeHealth in Denver, Colorado, is here to help you take control of your health. We administer calcitonin testing and help people like you with autoimmunity or thyroid conditions. Schedule your free consultation today!

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