Calcitonin: What It Is and How It Regulates Calcium Levels

Calcitonin is an important polypeptide hormone released by the thyroid gland in response to elevated serum calcium concentrations. 

Its primary function is to lower blood calcium levels by inhibiting bone matrix breakdown and, at the same time, stimulating urinary calcium excretion.

Here’s why calcitonin is crucial for cardiovascular and skeletal functions, and learn how to support the body’s calcium balance for healthy bones and overall well-being.

What is calcitonin?

Calcitonin is a hormone produced by the parafollicular cells, also known as C-cells, in the thyroid gland. Its primary function is to affect calcium levels in the blood by lowering them when they become elevated.

This polypeptide hormone works in opposition to parathyroid hormone (PTH), which is released by the parathyroid glands when blood calcium levels are low. 

PTH raises calcium levels by stimulating bone resorption and increasing calcium absorption in the intestines. While PTH increases calcium levels, calcitonin works to lower them, maintaining homeostasis.

In addition, calcitonin and human calcitonin gene-related peptides may help alleviate migraine and bone pain due to their potential analgesic properties, as reported by a study published in Molecular Pain.  

Watch the video below to learn more about calcitonin after a thyroid gland removal surgery.

The role of calcitonin in calcium regulation

Elevated blood calcium levels stimulate the release of calcitonin, which directly inhibits bone resorption. Thus, calcium release from bone is reduced, and blood calcium concentrations decline.

Calcitonin also increases urinary calcium output and indirectly limits the absorption of dietary calcium in the intestines. This contributes to overall calcium homeostasis by reducing excess calcium levels in the blood. 

Because of its calcium-regulating effects, calcitonin plays a role in maintaining bone density and skeletal health by preventing excessive calcium loss from the bone matrix.

It also supports cardiovascular health, as chronically elevated serum calcium concentrations can contribute to arterial stiffness and cardiovascular issues.

Research published in the Journal of Heart and Lung Transplantation investigated the therapeutic use of calcitonin for acute bone loss in heart transplant recipients. 

The authors concluded, “Prophylactic treatment with intranasal salmon calcitonin prevents rapid bone loss associated with high-dose steroids early after cardiac transplantation.”

Calcitonin has also been found beneficial in the management of postmenopausal osteoporosis, a condition where declining estrogen levels lead to increased bone loss and subsequent fracture risk. 

What are normal calcitonin levels?

A calcitonin blood test is the standard method for measuring calcitonin levels and is commonly used to evaluate bone metabolism and identify abnormalities in calcium regulation.

A normal calcitonin level is typically less than 25 picograms per milliliter (pg/mL) for males and less than 20 pg/mL for females. However, calcitonin reference ranges can vary depending on the laboratory and specific testing methods used. 

Low calcitonin levels may indicate an increased risk of osteoporosis, as reduced inhibition of bone resorption can lead to excessive bone matrix breakdown and calcium loss. 

In contrast, elevated calcitonin levels can be a sign of medullary thyroid cancer (MTC), a rare but serious condition, or C-cell hyperplasia, which may precede MTC.

As calcitonin plays a role in suppressing bone resorption, abnormal levels can also signal conditions such as Paget’s disease, acute bone loss, or other metabolic bone disorders. 

To diagnose and monitor these conditions effectively, physicians often use calcitonin testing in conjunction with other diagnostic markers, such as bone mineral density tests, to evaluate bone and calcium metabolism.

How to support healthy calcitonin levels

While calcitonin levels are mainly influenced by serum calcium concentrations, supporting bone health and promoting calcium balance can help maintain optimal calcitonin production.

Here are four ways to support healthy calcitonin levels.

1. Incorporate plenty of calcium-rich foods

Prioritizing nutritious foods rich in calcium, such as leafy green vegetables, dairy products, nuts, and sardines, supports optimal calcium levels, which are essential for maintaining healthy calcitonin production.

Lack of dietary calcium can disrupt calcium balance in the body, potentially leading to imbalanced calcitonin levels linked to poor bone health and an increased risk of osteoporosis. 

2. Support overall thyroid health 

Supporting optimal thyroid function is one of the best strategies for promoting healthy calcitonin levels. 

Nutrients such as iodine, selenium, and vitamin D are crucial for thyroid health, as they facilitate proper thyroid hormone synthesis, including calcitonin. 

Additionally, managing stress, reducing the intake of ultra-processed foods, and maintaining a nutrient-rich low-carb diet such as a Healthy Keto® diet can further support thyroid function and promote balanced calcitonin secretion.

3. Maintain optimal vitamin D status

Vitamin D is essential for regulating intestinal calcium absorption and maintaining calcium balance, which supports normal calcitonin levels.

In addition, a study published in the Journal of Bone and Mineral Research found that vitamin D influenced the expression of CALC1, a gene that belongs to the superfamily of related protein hormone precursors, including calcitonin.

This suggests that vitamin D may play a direct role in modulating CALC1 expression, potentially influencing calcitonin production and its functions in bone metabolism.

4. Avoid smoking 

According to research published in Endocrinology and Metabolism, smoking is associated with elevated calcitonin levels, especially in men.

While more research is needed on the long-term effects of smoking on calcitonin levels, these findings suggest that tobacco exposure may negatively influence calcium balance and, subsequently, skeletal health.  

FAQ

Sources

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC5524232/ 
2. https://pubmed.ncbi.nlm.nih.gov/15896748/ 
3. https://academic.oup.com/jbmr/article-abstract/7/10/1233/7500240
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC8090475/