Hyperthyroidism: what are the causes and symptoms? Fat?

The thyroid is one of the most important glands in the body, being responsible for secreting the hormones T3 and T4 (triiodothyronine and thyroxine), which participate in various processes in our body.

Unfortunately, some specific diseases and conditions can impair the production or correct secretion of these hormones, causing them to be released in excess or shortage.

When excess release occurs, it is characterized by hyperthyroidism, a disease that speeds up metabolism and causes several symptoms.

Continue reading the following text to find out about this condition!

Also understand the difference between low production ( hypothyroidism ) and hyperthyroidism


What is hyperthyroidism?

Hyperthyroidism is a disease in which the thyroid gland releases excess T3 and T4 hormones, which ends up interfering with the functioning of various body functions, such as metabolism.

The patient, in this condition, may present symptoms such as sweating, changes in heart rate, sudden weight loss, irritability and nervousness.

It can be triggered by a number of factors, which can be caused by an autoimmune response of the body, excess iodine, inadequate intake of thyroid hormones (treatment of hypothyroidism), thyroid surgery, presence of nodules, hormonal changes in pregnancy, among others.

It is more prevalent in women, between 20 and 50 years old, but it can also affect men.

The prognosis of the disease, however, depends a lot on the cause.

In most cases, drug treatment is sufficient to control hormone levels and promote remission of symptoms. In more severe cases, radioactive iodine therapies and surgery may be necessary.

Unfortunately, in most cases, there is no way to prevent it, but it is possible to lead a comfortable life with early diagnosis and proper treatment.

The doctor responsible for making the diagnosis and monitoring the patients, in this disease, is the endocrinologist.

In the International Classification of Diseases (ICD-10), hyperthyroidism is found by the code E05.

How does the thyroid work?

The thyroid is one of the glands in our body. It is constantly compared to the shape of a butterfly and is located in the throat (region of the Adam’s apple or gogó).

With an approximate weight of 15g to 25g, it is one of the largest and most important glands in the human body.

We can say that all the organism, in order to function perfectly, needs the glands to work in a harmonious way with each other.

In the case of the thyroid, functioning also depends on the pituitary gland, another gland located in the brain region.

It is the pituitary gland that produces the hormone that stimulates the production of the thyroid, TSH (thyroid-stimulating hormone or thyroid stimulating hormone, in Portuguese).

When the pituitary gland releases TSH, the thyroid produces the hormones triiodothyronine and thyroxine (T3 and T4), which interfere with our body’s functions such as our ability to concentrate, menstrual cycles, heartbeat, bowel function, muscle tone, mood and breathing, for example.

When, for some reason, the thyroid or pituitary gland does not function properly, the release of these hormones is impaired. As a result, diseases such as hyperthyroidism and hypothyroidism can develop.

Hyperthyroidism and hypothyroidism: what is the difference?

Many people confuse these diseases, but they are opposite conditions in the functioning of the thyroid and the biggest difference is in the dosage of hormones.

While in hypothyroidism the secretion of T3 and T4 is insufficient, in hyperthyroidism it is in excess. Thus, they cause different symptoms and complications.

In hypothyroidism, for example, the body slows down, as the metabolism cannot function properly with such low doses of thyroid hormones.

Therefore, in these cases, patients become more tired, have weakness, sensitivity to cold, weight gain and trapped intestines, becoming vulnerable even to diseases such as depression .

In hyperthyroidism, on the other hand, metabolism is very accelerated. Therefore, people may experience significant weight loss for no apparent reason, they become more intolerant to heat, the intestine becomes more functional, they experience excessive sweating, they become more irritable and anxious, among other symptoms.


Hyperthyroidism can occur as a result of other disorders of the endocrine system. One of the main causes is Graves’ disease, responsible for most cases of this condition.

However, inflammation in the thyroid, medications and nodules can also cause this variation in the dosage of hormones.

Understand a little more about these causes:

Graves’ disease

Graves’ disease is an autoimmune disease in which the patient’s antibodies attack thyroid cells, causing the production of T3 and T4 hormones to be excessive.

This is the main cause of hyperthyroidism, being a condition without forms of prevention and more common in women. It can manifest itself in patients of any age group, but it is more frequent between 20 and 50 years old.

A risk factor for this disease is family history. Therefore, people who have family members with the disease should be instructed to perform periodic tests to check the functioning of the thyroid and perform hormonal measurements through laboratory tests.


Goiter is a condition in which the thyroid gland has abnormal growth, which in some cases may be noticeable in front of the neck (forming a chat or swelling).

In some cases, it is caused by the presence of nodules (nodular goiter), but it can also be due to Graves’ disease, medicines, infections and iodine deficiency.

When a person is born with this thyroid dysfunction, it is characterized as a congenital goiter.


The thyroiditis is a condition caused by different types of inflammation of the thyroid gland. Some types of thyroiditis include subacute (Quervain’s thyroiditis), postpartum, Hashimoto’s and fibrotic thyroiditis.

In such cases, inflammation can cause both hypothyroidism and hyperthyroidism.

Subacute thyroiditis

Also known as Quervain’s thyroiditis, this is an inflammation of the thyroid without a well-defined cause, but likely to be related to viral infections in the region.

As it is a subacute condition, it is characterized as an inflammation that manifests within a few days, causing an enlarged gland (goiter) and, consequently, symptoms such as pain and discomfort during swallowing.

Post childbirth

Postpartum thyroiditis is an inflammation resulting from an autoimmune response, which can occur in pregnant women within the first year after delivery. It can occur with greater prevalence in women who have other autoimmune diseases , such as type 1 diabetes mellitus.

Tireoidite de Hashimoto

Hashimoto’s thyroiditis is also an autoimmune disease and one of the types of thyroiditis. However, unlike the others, it is one of the main causes of hyperthyroidism

Fibrotic thyroiditis

Also called Riedel’s thyroiditis, fibrotic thyroiditis is a chronic inflammation that occurs through an autoimmune reaction of the body. As it spreads through the tissues near the thyroid region, it ends up forming a more dense and hardened goiter.

In most cases, it causes hypothyroidism, but it can also end up triggering an excessive production of hormones.


Some medications, even supplements, that contain thyroid hormones in their composition can trigger a thyroid disorder.

They are one of the factors capable of causing hyperthyroidism when used improperly. In the treatment of hypothyroidism, for example, which is done with hormone replacement, the inappropriate use of this medication can cause hyperthyroidism.


The appearance of benign tumors in the pituitary or thyroid glands can also cause hyperthyroidism.

A compression caused by these tumors can increase the production of hormones T3 and T4.

Tumors in other parts of the body, such as the ovary and testis, can also cause some disorder in the thyroid by increasing the production of hCG, a hormone stimulated also during pregnancy.

HCG, like TSH, also increases the secretion of hormones T3 and T4.

Hyperactive pituitary gland

In these cases, the pituitary gland (or pituitary gland) releases TSH, a thyroid stimulating hormone, in greater quantities. This release can occur for several reasons, such as the presence of a tumor in the pituitary gland.

Subclinical hyperthyroidism

Subclinical hyperthyroidism is the condition in which the concentration of TSH in the blood is low and the levels of T3 and T4 are normal. Therefore, these patients do not usually show symptoms or, when they do, they are milder.

It is a much rarer condition than subclinical hypothyroidism.

In such cases, treatment may be different from that of patients with more severe hyperthyroidism.

The need for medication should be discussed with the endocrinologist, and it is necessary to monitor it regularly to assess the concentrations of these hormones in the blood.

Risk factors

There are groups that are more prone to hyperthyroidism, even though this is a disease that can affect anyone.

Be woman

Hyperthyroidism is a disease much more prevalent in women than in men. Graves’ disease, an autoimmune condition, occurs in 7 women for each man.

In addition, pregnancy also becomes a greater risk of developing some thyroid disorder, due to fluctuating hormone levels during this period.

Family history

Among the causes of hyperthyroidism, the main one is Graves’ disease, an autoimmune disease. One of the risk factors for this condition is family history, which consequently ends up being a risk for hyperthyroidism as well.

Hyperthyroidism in men

As seen, hyperthyroidism is much more common in women, but it can also affect men.

One of the factors that contribute to this difference in the number of cases between genders is, especially, due to the fact that Graves’ disease – the main cause of the disorder – is 5% more common in females.

In addition, the gestational period may also end up causing changes in hormonal dosages, which favors the greater number of cases of hyperthyroidism in women.

In men, hyperthyroidism can cause gynecomastia , a condition in which breast growth occurs as a result of excess hormones in the body.

However, it is not so common. It happens in one third of the patients, and it can be one of the first symptoms.

The primary treatment should be to regulate hyperthyroidism, to stabilize hormone levels.

For gynecomastia, a natural regression of breast growth can occur with the treatment of hyperthyroidism. In some cases, surgical interventions for tissue removal may be necessary.

Hyperthyroidism in pregnancy

During pregnancy, especially in the first 3 months, the woman’s body causes a greater stimulation of the thyroid to occur. This is because a greater number of hCG (human chorionic gonadotrophin) hormones are released, which, like TSH, also stimulates the gland to secrete T3 and T4 in higher doses.

In most pregnancies, this hCG stimulus does not occur or occurs for a very short and imperceptible period of time.

But sometimes, hyperthyroidism can develop. In these cases, the pregnant woman may experience symptoms such as weight loss, tachycardia, high blood pressure , tremors in the eyelids and enlargement of the thyroid (goiter).

To prevent and treat the condition, it is essential to monitor and diagnose the dosages of thyroid hormone levels, especially in the face of any symptom mentioned.

Does hyperthyroidism get fat?

No , what happens is usually the opposite.

People who have hyperthyroidism and who are not on treatment usually find it easy to lose weight, without much effort, due to the increased speed of metabolism – one of the main characteristics of the disease.

In hypothyroidism, the opposite usually occurs, due to the high levels of thyroid hormones in the body, which speed up the functioning of the metabolism, requiring greater energy expenditure and, consequently, interfere with the patient’s weight.

In hypothyroidism, insufficiency of hormones T3 and T4 causes a sluggish metabolism, which facilitates weight gain.

However, it is seen that, in some patients, especially in the younger ones, it is possible to gain weight with hyperthyroidism. In these cases, what interferes is the considerable increase in appetite and not a failure in the functioning of the metabolism.

But, in general, sudden weight loss is more characteristic as a symptom and not the other way around.

Hyperthyroidism symptoms

Excess thyroid hormones cause various reactions in the body, resulting in symptoms that are typical of hyperthyroidism. In this condition, the patient has an accelerated metabolism, which triggers symptoms such as tachycardia, excessive sweating, changes in the menstrual cycle and irritability.

By secreting hormones at high levels, hyperthyroidism accelerates the patient’s metabolism and thus promotes weight loss, even if the person does not change the diet. Other symptoms include:

Variations in the menstrual cycle

Because it is a disease that interferes with hormonal doses, it can also cause changes in the menstrual period. In hyperthyroidism, women may experience a reduction in flow and, in some cases, menstruation may pause.

Exophthalmos (wide eyes)

Exophthalmos is an inflammation that can affect patients who have hyperthyroidism because of Graves’ disease. In this condition, the patient may have bulging eyes, a consequence of the inflammation that “pushes” the eyes further.

Fast heartbeat

One of the symptoms of hyperthyroidism is the change it causes in the rhythm of the heartbeat. In this condition, unlike what occurs in hypothyroidism, they are more accelerated. Without treatment, this symptom can worsen for more serious problems.

Weight loss

People in this condition, because they have a faster metabolism, can lose weight even maintaining the same diet. It is considered a classic symptom of hyperthyroidism.

Increased appetite

At the same time that weight loss can occur without any apparent explanation, the patient with hyperthyroidism can also suffer from a significant increase in appetite. In some cases, this increased appetite can cause weight gain, but it is not the most common.


Gynecomastia is a condition in which abnormal breast growth occurs in men, due to an excess of tissue in the region. In hyperthyroidism, this happens due to the hormonal dysregulation that happens in the body.

Emotional changes

In addition to all physical symptoms, patients with hyperthyroidism may also suffer from some emotional variations. With untreated condition, they may become more irritable, nervous and anxious due to hormones.

Other symptoms

Hyperthyroidism can also interfere with the patient’s sensitivity to heat, causing greater sweating, cramps, fatigue and more frequent bowel movements

How is the diagnosis made?

The diagnosis of hyperthyroidism is usually performed by an endocrinologist, who evaluates the symptoms and orders blood tests to evaluate the dosage of hormones T3, T4 and TSH.

When there are more classic symptoms of the disease, such as sudden weight loss, heat intolerance, faster functioning bowels, tremors and palpitations, for example, the diagnosis may be easier.

However, this is not always the case, as the patient may present non-specific symptoms and do not indicate that there may be a variation in hormone levels.

Therefore, it is important that the endocrinologist does an efficient physical examination to investigate these symptoms.

In the physical examination, which usually occurs at the first contact with the doctor, the specialist listens to the patient’s complaints and assesses the symptoms presented by him.

At this time, it is important for the patient to tell if he also has other clinical conditions, if he is taking any medication and also to report on his sleeping and eating habits, as these are factors that may be associated with the disease.

In some cases, it is possible to check for swelling in the neck, which may indicate that the thyroid is in an abnormal size, one of the possible signs of the disease.


In consultation with the endocrinologist, the following exams can be done or ordered.

Blood test

The blood test performed to screen for hyperthyroidism can be done for three main purposes: for the measurement of TSH, T3 and T4.

From the result of these hormone levels, it is possible to confirm the diagnosis of the disease.

Radioactive iodine absorption test

In some cases, a radioactive iodine absorption test, which is also called a thyroid scintigraphy , may be ordered . It is not exactly a diagnostic test for hyperthyroidism, but it does help rule out other illnesses.

In this examination, the patient ingests a small amount of radioactive iodine, which is absorbed by the thyroid. From this, it is possible to obtain images of the thyroid through a device called gamma camera.

It can be done to rule out the possibility that it is a case of thyroid cancer , as the test identifies possible malignant nodules. When the exam indicates the presence of a nodule like this, the doctor may request a biopsy.


Ultrasound, a common image exam, can be done so that the doctor can better visualize the size and shape of the thyroid, assessing whether it is within the expected or if it is possible to identify any nodule.

It can also be done to identify whether these nodules are of solid or cystic mass.

Can hyperthyroidism be cured?

It depends . In some cases, hyperthyroidism can be cured, as in the case of hyperthyroidism caused by inflammation, tumors, medications or a diet rich in iodine. In such cases, despite remission, there are chances of recurrence.

However, when it comes to a case of hyperthyroidism due to Graves’ disease, there is no cure. Fortunately, under these conditions, patients can count on treatment to make the disease controlled.


The treatment of hyperthyroidism consists of the use of medication, administration of radioactive iodine or, in more severe cases, surgery.


The drug treatment of hyperthyroidism is done with antithyroid drugs and beta-blockers, which inhibit the production of excess thyroid hormones.

Radioactive iodine

Iodine, or potassium iodide, is a chemical substance present in human food. We consume it through food, using table salt. In small amounts, it is able to help keep the thyroid functioning.

Read more: Know the dangers of excess sodium

Radioactive iodine, in turn, is a substance used in medicine to help in the diagnosis and treatment of thyroid problems, being common in patients who have thyroid tumors, since this type of iodine is capable of destroying cancer cells.

There are, therefore, 2 types of radiation emitted by this iodine, being gamma radiation (similar to X-rays) and beta radiation, used in patients who still have cancer cells even after surgery to remove tumors.

In the case of hyperthyroidism, it can also be used as a treatment when the cause of the disease is the presence of a tumor.

However, it can also be indicated for patients with Graves’ disease or in other conditions that, for reasons that may vary, were unable to control the production of hormones with medications.


In some cases, when drug treatment is not enough to control hyperthyroidism, the patient may have to undergo a surgical procedure called thyroidectomy .

In this surgery, total or partial removal of the thyroid gland may be necessary.

After surgery, the treatment of these patients continues through the use of thyroid hormones, to prevent the opposite effect: hypothyroidism.


Drug treatment of hyperthyroidism is based on two main types of medication: antithyroid drugs and beta-blockers. They have an action in the body to inhibit this excess production of hormones.


These drugs are responsible for stopping the action of the thyroid when it is overactive, that is, secreting hormones T3 and T4 in high doses.

With medication, the symptoms start to be controlled, but it is not so immediate. It may take a few weeks or months for hormonal doses to be completely under control.

This treatment, in some cases, is not for life. There are patients who remain on drug therapy for one year, on average, and manage to have complete control of the disease. Others, however, may have relapses, which requires the use of the medication again.

The use should be made only with the guidance of the endocrinologist, who must follow up, as the drugs can cause serious side effects to the health of the liver, for example.

Other reactions that can occur in allergic people include hives, joint pain, fever and skin rashes.

Some examples of antithyroid drugs include Tapazole and Propylracil .

Beta blockers

Beta-blockers ( propranolol hydrochloride ) are commonly used to treat other diseases, such as hypertension.

In patients with hyperthyroidism, they are used to relieve symptoms, having no effect on the functioning of the thyroid.


NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained on this site is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.

Living together

Getting diagnosed with a disease is not easy. With the condition, many doubts about how the day to day will be from then on arise. So it is with those who have hyperthyroidism.

Despite being a disease with treatment and, in some cases, with complete remission, some changes may also be necessary and adaptations or healthy habits can be made to help with treatment:

Maintain a balanced diet

Patients in this condition should maintain a balanced and healthy diet, seeking nutritious foods that are good for the functioning of the thyroid, such as seaweed, quinoa , fish oil, Brazil nuts, milks, eggs, red meat.

Use of supplements

Hyperthyroidism can cause greater bone fragility, as it interferes with the absorption of calcium and vitamin D. In these cases, the doctor can guide the patient to also take supplements.

Practice exercises

Practicing physical activities is always valid. In addition to all the benefits, maintaining an exercise routine is important to strengthen the muscles and the cardiovascular system.


The prognosis of hyperthyroidism depends on the cause. In general, patients are able to treat the condition and lead a life without major difficulties or limitations. For this, they may need medication for the rest of their lives.

Without treatment, hyperthyroidism caused by Graves’ disease, for example, can cause serious health risks, worsening over time.

Complications: can hyperthyroidism kill?

Yes , hyperthyroidism when left untreated can worsen to the point of leading the patient to death, due to a series of complications that can trigger it.

The main complications include problems such as:

Eye problems

Some patients who have Graves ‘disease develop eye problems, a condition called Graves’ ophthalmopathy.

In that case, they may have more bulging, swollen or red eyes. They may also have greater sensitivity to light (photophobia), duplicated and blurred vision.


The amount of hormones secreted in hyperthyroidism interferes with the amount of calcium and other minerals important for bone health. Thus, patients who do not receive adequate treatment have a higher risk of developing osteoporosis .

Read more: Material restores bones and may replace bone marrow transplant

Heart problems

The hormones T3 and T4 can affect the heart rate, due to the faster metabolism.

With this cardiac variation, the patient is more vulnerable to cardiovascular diseases, such as heart failure, which can lead to death.

Gestational risks

Women with hyperthyroidism have a higher risk of having a miscarriage than pregnant women who do not have this disease.

Thyrotoxic crisis or thyroid storm

In this condition, the patient has a sudden increase in symptoms, in which they become more severe, accompanied by fever, rapid heartbeat and, in some cases, delusions.

When it occurs, urgent medical help is needed, as the patient may suffer severe sequelae, at risk of death.

How to prevent hyperthyroidism?

Hyperthyroidism, in most cases, is not a preventable disease, as when it is caused by Graves’ disease, when it develops during pregnancy or by a tumor, for example.

In some cases, certain precautions can be taken to try to prevent the disease, such as when it is caused by medication or by excess iodine.

In these situations, hyperthyroidism can be prevented by eating, with about 150 micrograms of iodine sufficient to preserve thyroid function.

For this, it is recommended to consume foods such as salmon, hake, cod and seafood.

It is also advisable to avoid excess food such as cabbage, cabbage and turnip, as they have a substance called thiocyanate, which can interfere with the functioning of the thyroid.

Like hypothyroidism, hyperthyroidism is also a very common thyroid disorder that can cause serious complications. Therefore, it is essential to maintain a routine of tests to measure the levels of hormones secreted by the gland.

Thanks for reading and keep following our articles on health and well-being!