Discover these 11 Causes of Low Thyroid (Hypothyroidism)

There are good odds that either someone you know or work with has low thyroid. After all, hypothyroidism affects 5 out of every 100 people in the United States. Hypothyroidism, also referred to as low thyroid or underactive thyroid, is a condition where the thyroid gland in the neck doesn’t produce enough thyroid hormones for the body. These hormones importantly play roles in functions like body temperature regulation, metabolism, and even development.

What Causes Low Thyroid?

Hypothyroidism can have a variety of causes ranging from a completely missing thyroid gland to the secondary effects of some medications and medical conditions. Here are just a few of the common conditions that can cause low thyroid levels…

11. Surgical Removal of the Thyroid

There are several reasons why the thyroid gland might need to be surgically removed. These range from cancer to rare medical conditions like Grave’s disease. When all or part of the thyroid gland is missing, it can dramatically impact the production of thyroid hormones. 

Why Surgical Removal of the Thyroid Causes Hypothyroidism

While removal of the thyroid might be medically necessary, it does come at the risk of either severely limiting or completing stopping the production of thyroid hormones. In cases where some of the thyroid gland remains, it can produce enough for the whole body even when damaged, but this event is not guaranteed. 

Another cause of severe thyroid problems comes when people are simply born with thyroid issues… 

10. Congenital (At Birth) Disease 

Some people are born with problems with their thyroid glands. In the United States and many other countries, babies are screened for these disorders at birth. Congenital hypothyroidism can significantly limit the thyroid hormones produced by the gland. 

Why Congenital Diseases Cause Hypothyroidism

People born with congenital hypothyroidism are born with either an impaired or non-functioning thyroid gland. This impairment can range from minor problems producing thyroid hormones to the body not producing them at all. This condition is treatable, but lasts throughout the person’s life. 

Another cause of low thyroid has to do with the treatment of other diseases… 

9. Radiation Treatment

Radiation can be incredibly dangerous and harmful, but when used by doctors currently, it can treat some of the most dangerous diseases. Radiation treatments are used to treat goiters, cancer, and rare diseases like Grave’s disease. 

Why Radiation Treatment Causes Hypothyroidism

Certainly radioactive treatments are designed to destroy the thyroid gland. This process might be medically necessary in some cases, although it can have devastating effects. This radiation involves using radioactive iodine to destroy the gland. Other radioactive treatments, especially those delivered to the neck, can harm the thyroid gland and lead to a low thyroid. 

Sometimes, the body itself is responsible for its own lack of thyroid hormones… 

8. Autoimmune Disease

Autoimmune diseases occur when the body’s own immune system goes haywire. In these diseases, the immune system mistakenly identifies part of the body as an infection and orders white blood cells to attack the body itself. This event can happen to the thyroid gland. 

Why Autoimmune Disease Causes Hypothyroidism

A disease called Hashimoto’s thyroiditis is caused by the immune system falsely attacking the thyroid gland. This event can lead to severe consequences, including the gland not being able to produce enough thyroid hormones for the body. 

In order for the thyroid to function properly, your body needs to be getting enough iodine… 

7. Too Little Iodine

An iodine deficiency prevents the thyroid from getting the iodine it needs to function properly. While iodine deficiencies are very uncommon in the United States, they are still a concern. This fact can be especially true for people with diets that avoid foods commonly rich in iodine, such as iodized salt, shellfish, and eggs. 

Why Too Little Iodine Causes Hypothyroidism

Just like the rest of our body needs vital nutrients in order to run properly, the thyroid gland needs iodine in order to function. When iodine levels get too low, the thyroid can run out of the resources it needs to produce thyroid hormones, leading to low thyroid levels. 

Another cause that interferes with the thyroid gland’s ability to do its job involves the pituitary gland… 

6. Pituitary Gland Problems

Your pituitary gland is a small part of your body tucked away in the base of your brain. This gland is about the size of a pea and, despite its small stature and secretive location, it plays an incredibly important role in your body’s chemistry. 

Why Pituitary Gland Problems Causes Hypothyroidism

The pituitary gland is the “master control” for all of your other glands. The pituitary gland, in other words, is responsible for releasing hormones that cause other glands to grow and function normally. Events like traumatic injuries and tumors can disrupt this gland, which in turn disrupts the thyroid gland. 

Sometimes the medications we take to treat other conditions have side effects that can disrupt our thyroid gland as well… 

5. Medicinal Side Effects

Every medicine comes with its own side effects. Usually, we find a medicine that has side effects we can work with or don’t experience at all. Not all medicines with side effects function the same way for everyone, though. Some medicines, for instance, can cause problems with the thyroid. 

Why Medicinal Side Effects Cause Hypothyroidism

Depending on which medicines a person takes, they can experience problems with their thyroid gland, leading to hypothyroidism. These medications typically interrupt the thyroid by triggering a genetic predisposition to other thyroid problems, including autoimmune disorders. 

Some causes of hypothyroidism are the direct result of other disorders and diseases… 

4. Amyloidosis

Amyloid disease, or amyloidosis, is a rare disease caused by a buildup of amyloids. Amyloids are a type of protein that are not usually found in the body. Amyloidosis is caused when other proteins transform into amyloids, get deposited into otherwise healthy organs, and disrupt the normal function of the body. 

Why Amyloidosis Causes Hypothyroidism

In patients with amyloidosis, amyloids can be deposited into the thyroid gland. Over time, these invasive proteins start to clog up the thyroid and impact its ability to make enough hormones for the body to function normally. 

Stray proteins aren’t the only thing that can infect the thyroid. Any disease or condition that causes the thyroid to swell can impact the production of hormones, too… 

3. Thyroiditis

Certain autoimmune conditions or viral infections can get inside of the thyroid gland and disrupt its functioning. These conditions can cause quick changes in the amount of thyroid hormones being produced by this gland. 

Why Thyroiditis Causes Hypothyroidism

Thyroiditis is inflammation of the thyroid, which can disrupt normal thyroid production. This condition can come in two waves. The first features the thyroid dumping its thyroid hormones into the blood, which temporarily causes hyperthyroidism (overactive thyroid). The second is hypothyroidism (low thyroid) while the body struggles to recover from this sudden deficit of needed hormones. 

The brain is an amazing organ full of complexities. When things go out of whack somewhere in the brain, it can have far-reaching consequences, including hypothyroidism… 

2. Problems with the Hypothalamus 

The hypothalamus is another small region at the base of the brain. This region functions something like the brain’s regulator. Simply put, the hypothalamus is responsible for regulating sleep, temperature, hunger, and hormone production. In this sense, it is the part of the brain that gives the pituitary gland its orders. 

Why Problems with the Hypothalamus Cause Hypothyroidism

In a very rare case, the hypothalamus can have trouble producing some of the hormones that the body needs to function. In particular, a hormone known as TRH can change how the thyroid functions; this hormone gives the pituitary gland instructions on how to operate. If there is a problem with this hormone, the thyroid can experience a variety of problems. 

When it comes to the delicate balance of hormones in the body, pregnancy can throw everything out of order… 

1. Pregnancy

Pregnancy is both a wonderful time and a challenge for the body. While pregnant, the human body undergoes massive changes, including changes in hormone levels. For reasons that are still unknown, some pregnant individuals experience a severe drop in thyroid hormones shortly after their pregnancies end. 

Why Pregnancy Causes Hypothyroidism

This condition is known as postpartum thyroiditis. Shortly after the end of the pregnancy, there will be a sharp burst in the production of thyroid hormones followed quickly by a prolonged drop in thyroid production. Most individuals who experience postpartum thyroiditis fortunately will see their thyroid levels return to normal over time, though. 

Final Thoughts

Problems with the thyroid aren’t easy to diagnose without the help of a doctor. With causes ranging from not getting enough iodine to rare diseases, thyroid problems can be difficult to pin down to a single cause. If you suspect that you are experiencing issues with your thyroid gland, visiting your doctor to rule out more serious conditions is a solid first step. 


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