Hypothyroidism: know the symptoms, treatments and causes.

Have you ever heard of hypothyroidism? This is a relatively common disease of the thyroid gland, with a prevalence of 2% in the general population and 15% in elderly individuals .

The changes caused by hypothyroidism are due to dysfunction of the thyroid, a small gland located in the front of the neck that produces the hormones T3 (triiodothyronine) and T4 (thyroxine). Both are essential for the proper functioning of the human body, since they control the metabolism and the performance of various organs.

The good news is that, when diagnosed early, this disease can be easily treated. In this article we will approach what is hypothyroidism in a more complete way, as well as what is its cause, the symptoms of this dysfunction and what is the indicated treatment to treat the symptoms. Check out!

What is hypothyroidism?

The pituitary gland is located in the human brain and one of its functions is the production of TSH. This hormone is responsible for stimulating the thyroid to produce T3 and T4, the hormones that control the body’s metabolism.

Hypothyroidism is characterized by low production of these hormones and can have two general causes: primary and secondary. Most cases (about 95%) are caused by primary hypothyroidism, that is, a failure in the thyroid gland itself to produce thyroid hormones.

Secondary hypothyroidism, which is much less prevalent in the population, occurs when there is a defect in the pituitary gland that compromises TSH levels. Thus, the thyroid stimulus will be insufficient, as will the production of T3 and T4.

What causes hypothyroidism?

Primary hypothyroidism

Primary hypothyroidism is characterized by low levels of T3 and T4 and high levels of TSH. That’s because the pituitary gland keeps its work normally active and tries to over-stimulate the gland in order to supply the lack of thyroid hormones.

Hashimoto’s thyroiditis

In this disease, the body produces hormones that attack the thyroid gland and destroy it, which characterizes an autoimmune reaction. In this way, she becomes unable to produce thyroid hormones or produces them in small quantities.

Lack of iodine

Iodine is one of the components of thyroid hormones. Thus, diets with low or no iodine intake can cause hypothyroidism, since the thyroid will have no substrate to produce T3 and T4.

To reduce the problem, iodine was added to the table salt.


Some drugs and medications can cause low production of T3 and T4. Examples include amiodarone, lithium, sodium valproate, tyrosine kinase inhibitors and immune system inhibitors.

Secondary hypothyroidism

Dysfunction in the hypothalamus

The hypothalamus is a small command center in the brain that is close to the pituitary gland. Its function is to generate nerve impulses and hormones that control this gland. Thus, dysfunctions in the hypothalamus, such as tumors, affect the region and can cause deficiency in stimulating the pituitary gland.

Consequently, there is also a decrease in the stimulus for the thyroid, causing hypothyroidism.

Pituitary dysfunction

The pituitary gland is a gland that can function abnormally for several reasons. In many cases, there is a benign tumor (mass), called adenoma.

In the case of hypothyroidism, the tumor can grow to the point of putting pressure on normal pituitary cells, which causes deficiency in TSH production and less stimulation of the thyroid.

What are the symptoms of hypothyroidism?

The symptoms caused by hypothyroidism can fluctuate and present differently in each individual. In general, the condition always begins slowly and insidiously, with tiredness being the first symptom reported by patients with this dysfunction.

T3 and T4, as mentioned, are hormones that control the metabolism and the functions of various organs. Thus, there is a generalized dysfunction. As the body slows down, it is natural for some people to gain extra pounds or find it difficult to lose weight, for example.

In addition to tiredness, the person feels weak, unwilling and may have slow thinking, with learning difficulties and memory fixation. Hair can become dry and nails brittle.

Changes in the cardiovascular system, such as decreased heart rate and increased blood pressure, and in the digestive system, such as constipation , are also among the symptoms. Finally, reproduction problems can also occur, since low levels of thyroid hormones can cause menstrual irregularity, low libido and infertility.

How is the problem diagnosed?

When noticing the above symptoms, it is necessary to seek an endocrinologist, since this is the specialty that takes care of the hormonal part of the body. To diagnose the problem, the doctor orders some tests to identify the levels of T3 and T4 in the body, as well as that of TSH.

Low levels of T4 or T3 and high level of TSH indicate a primary thyroid dysfunction, since the pituitary gland is producing more TSH to supply the demand for thyroid hormones.

However, low levels of T3 and T4 associated with a low level of TSH indicate a secondary dysfunction, in which the problem is in the pituitary or hypothalamus. If this is the case, the doctor will instruct the patient to perform other tests, such as head tomography, in order to diagnose the problem.

How is hypothyroidism treated?

Treatment for symptoms of hypothyroidism is relatively simple. There is a medication that consists of synthetic thyroid hormones, called levothyroxine. Ingestion of this medicine increases the levels of T3 and T4, restoring the body’s normal function.

The initial dose is given based on the patient’s degree of symptoms and, after that, follow-up is necessary to identify the right dose for each one. Therefore, the endocrinologist monitors TSH levels, which are a measure of the effectiveness of the treatment.

So, did you understand what hypothyroidism is? This disease has easy diagnosis and cure, but its non-treatment can lead to some risks. Low hormone levels, for example, can lead to peripheral neuropathy, a condition that causes pain, tingling and can even cause loss of sensation.

If decompensation persists, arrhythmias and heart failure may occur , as T3 and T4 control cardiac functions. Therefore, when suspecting the disease, seek medical advice quickly.

Did you like our article on hypothyroidism? Want to know in what other situations should an endocrinologist be  sought? So, be sure to read this post!

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