Let's learn more about calcitonin, which helps control calcium in your body.

Today we are going to talk about a small but very important hormone in our body. It is a hormone called calcitonin . You may not have heard of this name before. But it plays a big role in keeping your body's calcium levels in check. So, let's take a look at what calcitonin is, how it works, and what happens if its levels change.

What is Calcitonin?

Simply put, calcitonin is a hormone produced and released by your thyroid gland (yes, that butterfly-shaped gland in the front of your neck). Its main job is to lower and control the level of calcium in your blood. Think of it like a calcium policeman, coming in when the calcium in your blood is too high and lowering it.

This calcitonin hormone works against the action of another hormone called parathyroid hormone (PTH). Parathyroid hormone (PTH) increases the calcium level in your blood. So these two are like a tug-of-war, maintaining the calcium balance in our bodies.

Calcitonin is produced and secreted by the C-cells (also called parafollicular cells) in your thyroid gland .

But the strange thing is, scientists still don't fully understand the full significance of this calcitonin hormone. They know what it does, but they don't really understand why we have this hormone. Even when calcitonin levels are abnormal, it causes very few, if any, major symptoms.

Is calcitonin used as a medicine?

In the past, some doctors have prescribed synthetic forms of calcitonin as a treatment for conditions such as Paget's disease of the bone and hypercalcemia, which is an excess of calcium in the blood.

However, newer, more effective medications (for example, bisphosphonates) are now available. Because of the advent of bisphosphonates , doctors rarely use calcitonin as a treatment.

What does calcitonin actually do?

The main job of the hormone calcitonin is to lower the level of calcium in your blood (not in your bones, but in your blood). It does this in two main ways:

1. Prevents bone fractures: There is a type of cell in our body called osteoclasts. These are the ones who break down bones and release the calcium in the bones into the blood. The hormone calcitonin temporarily stops the activity of these osteoclasts. Then, the amount of calcium coming from the bones into the blood decreases. It is like closing a gate.

2. Reduces calcium reabsorption from the kidneys: Calcitonin can also reduce the amount of calcium your kidneys reabsorb into the blood. This results in a decrease in blood calcium levels.

Think of the calcium level in your blood as being like the water level in a water tank. Calcitonin, on the one hand, reduces the amount of water entering the tank (by stopping calcium from coming out of the bones), and on the other hand, it sends some water out of the tank (through the kidneys).

What influences the secretion of calcitonin?

Your thyroid gland releases calcitonin based on the level of calcium in your blood.

• When your blood calcium levels increase , the thyroid gland releases more calcitonin.
• When blood calcium levels drop , the thyroid gland reduces the amount of calcitonin it secretes.

This works like an automatic system.

How to check calcitonin levels?

Your doctor can do a blood test to check your calcitonin levels.

But remember, because abnormal calcitonin levels usually don't cause symptoms, doctors don't recommend this test for everyone. Calcitonin blood tests are usually recommended for the following reasons:

• Find out if you have a rare type of thyroid cancer called Medullary Thyroid Cancer (MTC) or a condition called C-cell hyperplasia (this is not cancer, but an abnormal growth of C-cells).
• If you are someone who is being treated for medullary thyroid cancer (MTC), see how successful that treatment is.
• If someone in your family has a genetic condition called Multiple Endocrine Neoplasia (MEN type 2).

What are normal calcitonin levels?

In general, the normal range for calcitonin is as follows:

• For men: less than 25 pg/mL (picograms per milliliter).
• For women: less than 20 pg/mL (picograms per milliliter).

But it's important to remember this: This normal range can vary from lab to lab. Therefore, the normal range on your blood test report is the one you should be focusing on.

If you have a calcitonin test, your doctor will explain your results to you and tell you whether further tests are needed.

What happens if calcitonin levels increase?

High levels of calcitonin don't seem to cause any major harm to your body, and they don't cause any specific symptoms. However, high levels of calcitonin can be a sign of two rare conditions:

1. Medullary Thyroid Cancer (MTC): This is a rare cancer that starts in the C-cells (calcitonin-producing cells) of the thyroid gland. This cancer can cause those C-cells to produce too much calcitonin.

2. C-cell hyperplasia: This is not cancer (benign). However, it is an abnormal growth of C-cells. This enlarged tissue can produce too much calcitonin. Sometimes, this C-cell hyperplasia can develop into medullary thyroid cancer (MTC).

So, if you have symptoms of either of these two conditions, your doctor may recommend a calcitonin test.

What happens if calcitonin levels decrease?

Low levels of calcitonin don't seem to have a big impact on your body. There are people who have had their thyroid gland completely removed, meaning their calcitonin levels are undetectable. They also don't have any symptoms related to their blood calcium levels.

This is why scientists believe that mechanisms other than calcitonin primarily contribute to the control of calcium in our bodies.

What is the difference between Parathyroid Hormone (PTH) and Calcitonin?

Parathyroid hormone (PTH) and calcitonin both help control the level of calcium in your blood. But the difference is how they do it and how much they affect your calcium levels.

• Parathyroid hormone (PTH): This hormone increases the level of calcium in your blood. It also helps control the level of phosphorus in your blood and bones. It also activates vitamin D.
• Calcitonin: This lowers the calcium levels in your blood.

However, parathyroid hormone (PTH) appears to play a more important role than calcitonin in regulating the level of calcium in our blood. Scientists know this primarily because abnormal levels of PTH can lead to serious conditions such as hypercalcemia (high blood calcium) or hypocalcemia (low blood calcium). On the other hand, abnormal levels of calcitonin don't have much effect on your body.

What is the difference between Calcitonin and Calcitriol?

Calcitonin and calcitriol are both hormones that affect calcium levels, but they work differently.

• Calcitriol: This is also called active vitamin D. It increases the level of calcium in the blood. Do you know how it does that? It increases the amount of calcium that can be absorbed into your intestines from the food you eat. Then that calcium is added to your blood. Calcitriol also prevents the loss of calcium from the kidneys. Parathyroid hormone (PTH) stimulates the enzyme that converts vitamin D to calcitriol.
• Calcitonin: As mentioned earlier, this helps reduce calcium levels in the blood.

So you see, calcitonin is a bit of a mysterious hormone. Its levels, whether low or high, don't cause major side effects. However, don't forget that elevated calcitonin levels can be a sign of conditions like medullary thyroid cancer (MTC) or C-cell hyperplasia.

Things to Know (Take-Home Message)

Okay, so today we've talked a lot about calcitonin. Let's now look at the most important things you need to remember.

• Calcitonin is a hormone produced by your thyroid gland that helps lower the level of calcium in your blood.
• Although its exact significance is not yet fully understood, it works against parathyroid hormone (PTH) and contributes to calcium control.
• Because abnormal calcitonin levels do not cause major symptoms, a blood test to check this is only done in special cases.
• The most important thing is: Elevated calcitonin levels can be a sign of two conditions: medullary thyroid carcinoma (MTC) or C-cell hyperplasia.
• If you have symptoms of these conditions, or have questions about your risk of developing them, be sure to see your doctor for advice. They are ready to help you.

So, I hope this information was useful to you. Stay healthy!

` Calcitonin, thyroid, calcium, hormone, medullary thyroid cancer, C-cell hyperplasia, parathyroid hormone