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Hyperthyroidism

Some causes of hyperthyroidism may disappear without treatment. Hyperthyroidism caused by Graves’ disease progresses to the worse with time. Complications range from severe to life quality altering. 

Overview

 

Hyperthyroidism or overactive thyroid disease is a disorder that means extra amounts of the thyroid hormone are produced and released by the  thyroid gland. . The most common cause of hyperthyroidism is Graves’ disease. Other causes are hyperfunctioning thyroid nodules, thyroiditis,  iodine consumption , thyroid hormone medicine, and high levels of human chorionic gonadotrophin.

Hyperthyroidism is more common in women, people with other thyroid problems, people over 60 years old , people with medical conditions such as certain common viral infections , history of other autoimmune disorders , and pernicious anemia.

The thyroid gland is an organ located in the front of the neck that releases thyroxine (T4) and triiodothyronine (T3) hormones, which play an important role of how the whole body functions. When the thyroid gland is overactive, the body’s processes are accelerated and t some symptoms appear such as nervousness, anxiety, fatigue, increased sensitivity to heat, trouble sleeping, weight loss, irregular heartbeat or pounding of the heart, mood swing, among other symptoms.

Hyperthyroidism is diagnosed based on symptoms, physical exam, blood tests, radio iodine uptake test, and thyroid scan. Hyperthyroidism can be treated in several ways radioactive iodine, anti-thyroid medications, and beta blockers.

If left untreated, hyperthyroidism can lead to many problems which include heart problems, brittle bones, eye problems, and an underactive thyroid. Hyperthyroidism cannot be prevented in the case where Graves' disease is the cause. A few ways that may reduce the development of hyperthyroidism may include avoiding consumption of  thigh quantities of iodine, using thyroid medications according to the doctor’s recommendations  to avoid an overdose, and regular screening when a family history is present to detect problems early.

 

Definition

Hyperthyroidism is a condition by which excessive amounts of the thyoroid hormones are secreted by the thyroid gland. 

Causes

Some common causes of hyperthyroidism include:

 1-Autoimmune disorder Graves’ disease

 

In this disorder, the immune system is responsible for producing antibodies that attack the  thyroid gland making it being overactive and releasing extra amounts of T-4 hormone. Graves’ disease, with an unknown cause, is the most common cause of hyperthyroidism that mostly affects young or middle-aged women.  

2-Hyperfunctioning thyroid nodules (toxic adenoma, toxic multinodular goiter, Plummer's disease)

 It is where the growth of one or more nodules or lumps in the thyroid  gland lead to an increased activity and   T-4 hormone  production. . An adenoma is an isolated part of the gland that forms a wall for its isolation and  noncancerous (benign) lumps that may cause the thyroid  to be enlarged. The real reasons behind the production of excessive amounts of hormones is not well understood although not all adenomas produce excess T-4. 

3-Thyroiditis

 A viral infection or a malfunction in  the immune system  are the reasons  why the thyroid gland becomes inflamed and produces extra thyroid hormone that leaks into the bloodstream. (4) Hyperthyroidism could last for a period of 3 months to be then reversed into hypothyroidism where the gland becomes underactive. The  usual  time for hypothyroidism is 12 to 18 months, but sometimes it becomes permanent. The conditions of thyroiditis that cause hyperthyroidism followed by hypothyroidism are: 

  • Subacute thyroiditis

It causes  an enlarged thyroid gland with pain.

  • Postpartum thyroiditis

It is  painless and occurs after pregnancy.

  • Silent thyroiditis

This condition involves a painless, and a possible enlarged thyroid. Silent thyroiditis is thought to be as a probable autoimmune condition. 

4- Iodine

 The consumption of iodine affects the amount of  the thyroid hormone produced by thyroid gland. In some  individuals, consumption of large quantities of iodine may cause the thyroid to produce too much thyroid hormone. Some medications and cough syrups contain high content of iodine. 

5- Thyroid hormone medicine

 The high intake of thyroid hormone medicine as a treatment for hypothyroidism may lead to hyperthyroidism. Interaction among thyroid hormone medicine and other medication may raise hormone levels  and therefore doctor consultation is necessary when starting new medication. 

6-High levels of human chorionic gonadotrophin

 Increased levels of chorionic gonadotrophin in the body may cause hyperthyroidism that occurs in early pregnancy,  multiple pregnancies or in a molar pregnancy. 

7- Pituitary adenoma

 It is a benign tumor of the pituitary gland that is located at the base of the brain.   This tumor affects the level of hormones produced by the thyroid. 

8-Thyroid cancer

 Cancerous thyroid tumors can rarely affect the production of thyroid hormones. 

Risk Factors

The risk of developing hyperthyroidism is increased by the following factors:

  • Gender

Women are more likely to develop hyperthyroidism than men.

  •  Age

Any age is a possible chance for hyperthyroidism but the chances are increased by the age of 60 or older. 

  • Genetic Factors

A family history of Graves’ disease or other forms of hyperthyroidism may increase the risk of hyperthyroidism.

  • Ethnic Background

The involvement of Japanese ancestry  in individuals renders them at a greater risk of hyperthyroidism,  which can go back to a diet high in saltwater fish, which are rich sources of iodine. 

  • Medical Conditions

Medical conditions that may increase the risk of hyperthyroidism include:

-Certain common viral infections.

-History of other autoimmune disorders.

-Pernicious anemia, a condition caused by a vitamin B12 deficiency. 

-Type 1 diabetes. 

Primary adrenal insufficiency, a hormonal disorder. 

Pregnancy within the past 6 months. 

Pathophysiology

The thyroid is a small, butterfly-shaped gland located at  the front of the neck. The energy used by the body is regulated by the thyroid hormones so almost every organ in body is affected by the thyroid hormones, even heart beat rhythms. 

Two hormones are secreted by the thyroid gland  thyroxine (T4) and triiodothyronine (T3). The functions of the body are highly governed by these hormones, these functions include maintaining the rate by which the body uses fats and carbohydrates, helping to control the body temperature, influencing heart rate, and helping in the regulation  of the production of protein. 

The hypothalamus sends signals to the pituitary gland  to produce thyroid-stimulating hormone (TSH) which depends on the quantity of)  T4( and)  T3( for its amount released . When the thyroid gland receives TSH, it regulates the production of hormones.  When excessive amounts of T4 and T3 are produced this is called hyperthyroidism. 

Signs And Symptoms

The symptoms may develop gradually or suddenly, symptoms of hyperthyroidism can vary from person to person and may include:

  • Nervousness, anxiety or irritability.
  • -Fatigue.
  • Increased sensitivity to heatandheat tolerance problems. .
  • -Trouble sleeping.
  •  Tremors (trembling of the hands and fingers).
  •  Rapid heartbeat,  irregular heartbeat or pounding of the heart.
  • Frequent bowel movements or diarrhea.
  • Weight loss.
  • Mood swings.
  • - An enlarged thyroid gland that is also known as goiter. 
  • Changes in menstrual patterns in women.
  •  Increased perspiration.
  •  Muscle weakness.
  •  Increased appetite. 
  • Continuous tiredness and weakness.
  •  Hair loss. 
  • Breast development in men.
  • Clammy skin.
  • High blood pressure.
  • Itchy or irritated eyes. 
  • Itchy skin.
  • Nausea and vomiting.
  • Protruding eyes (exophthalmos).
  • Skin blushing. 
Diagnosis

Symptoms and blood test results are indicators ofhyperthyroidism which are:  

  • Medical history and physical exam

The patient should be checked for a slight tremor in fingers, overactive reflexes, eye changes, warm and moist skin, examining thyroid gland swallowing to check whether it is enlarged, and check for rapid pulse .

  • Blood tests

Blood tests that measure the levels of the following diagnose hyperthyroidism:

1-Thyroid function blood test

  • The levels of the thyroid function is checked via these tests: Thyroid-timulating hormone (TSH) which isa hormone produced by the pituitary gland that controls the production of the thyroid hormones.
  • Triiodothyronine (T3) a main hormone produced by the thyroid gland
  • Thyroxine (T4)  another main hormone produced by the thyroid gland. . 

An overactive thyroid is manifested in alow level of TSH and high levels of T3 and/or T4 . In older adults, classic symptoms of hyperthyroidism may be absent which makes these tests essential in this case for diagnosis. 

2- Anti-thyroid antibodies test

This test can determine the kind of antibodies that attack the thyroid tissue  which can help diagnose Graves' disease and autoimmune thyroid disorders. 

3- Erythrocyte sedimentation rate (ESR)

Inflammation in body is detected through an erythrocyte sedimentation rate (ESR) test . Signs of inflammation indicate that the cause of the increase in thyroid hormones is due to thyroiditis. 

 

  • Radio iodine uptake test

This test uses radioactive iodine (radioiodine)to be taken asa small oral dose of radioactive iodine  and later on,  the thyroid gland is checked on time intervals of two, six or 24 hours to measure the amount of radioactive iodine absorbed by the thyroid gland. Iodine is used by the thyroid gland to  produce hormones When a high amount of   radioactive iodine is absorbed, this means that the thyroid gland is producing too much thyroxine (T4) which is mainly caused by either Graves' disease or hyperfunctional  nodules. Hyperthyroidism  that is accompanied by a low uptake of radioactive iodine indicates that the thyroxine stored in the gland is leaking into the bloodstream and probably thyroiditis. It is worth mentioning that the amount of radiation that patient is subjected to in this test is small.

 

 

  • Thyroid scan

A radioactive iodine tracer is used in this test to examine the structure and function of the thyroid gland. and includes the injection of a small amount of a slightly radioactive substance that is absorbed by  the thyroid gland. Following that, a scan is conducted to check the amount of the radioactive substance absorbed, in addition to examinning the size and shape of the thyroid. 

Treatment

Hyperthyroidism can be treated easily and in several ways. Without treatment, hyperthyroidism may lead to serious problems. Age, physical condition, the underlying cause of the hyperthyroidism, and the severity of disorder define the treatment used. Treatments of hyperthyroidism include:

  1. Radioactive iodine

The absorption of the radioactive iodine by the thyroid gland leads to the shrinkage of the  gland and  for symptoms to subside, in addition to causing hypothyroidism by slowing the activity of the thyroid gland which  may eventually require taking medication every day to replace thyroxine. Radioactive iodine has been used over the past60 years to treat hyperthyroidism and is considered generally safe. 

  1. Anti-thyroid medications.

These medications  stop the thyroid gland from producing excess amounts of hormones which causes gradual reduction of hyperthyroidism symptoms. . These drugs are propylthiouracil and methimazole, and both can  cause serious liver damage, and sometimes leadi to death. Propylthiouracil  should be used when methimazole intolerance exists and is responsible for causing  far more cases of liver damage. . Skin rashes, hives, fever or joint pain  may occur in a small number of people who are allergic to these drugs . 

 

  1. Beta blockers.

These drugs reduce some symptoms of hyperthyroidism like a rapid heart rate and help prevent palpitations, and are commonly used to treat high blood pressure. . Side effects may include fatigue, headache, an upset stomach, constipation, diarrhea and dizziness.

  1. Surgery (thyroidectomy).

Surgery is used in cases of pregnancy, intolerance for anti-thyroid drugs  , and in the case where radioactive iodine therapy  is not possible or not available.. Thyroidectomy involves the partial or whole removal of the thyroid gland which poses risks of damaging the vocal cords and the parathyroid glands. Furthermore, the need for a lifetime treatment with levothyroxine is required in order to supply the body with sufficient amounts of the thyroid hormone. In the case where the parathyroid glands are removed, medications that maintain the blood –calcium levels are required.

 

  1. Lifestyle and home remedies  
  •  Once treatment begins,  symptoms subside. Reducing these symptoms is achieved by:Asking doctor about supplementing your diet.

Excessive weight gain can be observed upon treatment of hyperthyroidism which requires  nutritional  food that is balanced and does not contain extra calories. Sodium and calcium in the appropriate amounts are important for people with hyperthyroidism. 

 

  • Getting enough calcium and vitamin D.

Bones become thinner because of hyperthyroidism which makes it important to  get enough calcium and vitamin D to help prevent osteoporosis. 

Complications

Untreated hyperthyroidism can lead to serious complications which are:

 

1-Heart problems

It is considered the most severe complication of hyperthyroidism that involves the heart. Reversible complications with appropriate treatment include heart problems such as rapid heart rate, a heart rhythm disorder called atrial fibrillation and congestive heart failure. 

2-Brittle bones

It is known as osteoporosis which means that it is a weak or fragile bone. The bone is strong when it has the appropriate amount of calcium and other minerals . Untreated hyperthyroidism can also lead to Brittle bones.. When there are high levels of the thyroid hormone, the body’s  ability to  absorb calcium into the bones is obstructed. 

 

3-Eye problems

 In this case , they areknown as thyroid eye disease or Graves' ophthalmopathy. One in three people are affected by an overactive thyroid caused by Graves' disease. 

 Symptoms include eye problems;  bulging eyes, red or swollen eyelids , eyes feeling dry, sensitivity to light, and blurring or double vision. Most cases are considered mild but do get better when the overactive thyroid is treated. Severe eye problems can lead to vision loss, when untreated. 

Referral to an eye specialist(ophthalmologist) in this case is needed for treatment.  Treatment includes eye drops, steroid medication or possibly surgery. 

 

4-Underactive thyroid

This happens when treatment of an overactive thyroid leads to an underactive thyroid (hypothyroidism).. The symptoms of an underactive thyroid, include sensitivity to cold , tiredness , weight gain , constipation, and depression. An underactive thyroid requires long-term treatment with thyroid hormone medication and in most cases it is permanent but in some cases it is temporary.

 

5-Pregnancy problems

The chances of miscarriages, preeclampsia, preterm birth or low birthweight of baby are increased by  hyperthyroidism. .

Using contraception is advised when there is no planning for a pregnancy, since. some treatments for an overactive thyroid can harm an unborn baby. 

 

6-Thyroid storm

This happens when there is little control over an overactive thyroid which can lead to a serious, life-threatening reaction. The incidence of a thyroid storm is increased in these cases, an individual with aserious health problem along with hyperthyroidism especially people with an infection, an incorrect way of taking medication, damage to the thyroid gland, and pregnancy in women.

The common symptoms of a thyroid storm are:

  • Rapid heartbeat.
  • High temperature (fever) over 38 °C (100.4  °F).
  • Diarrhoea and vomiting.
  • Yellowing of the skin and eyes (jaundice).
  • Severe agitation and confusion.
  • Loss of consciousness. 

 

7-Red, swollen skin

People with Graves' dermopathy which affects the skin by causing redness and swelling mostly on the shins and feet. 

8-Thyrotoxic crisis

The thyrotoxic crisis leads to fever, rapid pulse and even delirium. 

Prevention

Mainly, hyperthyroidism  caused by a genetic disease known as Graves' disease cannot be prevented.

A few measures that may help reduce the chances of having hyperthyroidism may include:

1-  Avoiding  high consumption  of iodine that is found in high amounts in salt water fish.

2- Applying the doctor’s recommendations in using thyroid medications in order to avoid overdoses.

3- When there is a family history of hyperthyroidism, regular screening may help detect problems early and prevent complications. 

Prognosis

Some causes of hyperthyroidism may disappear without treatment. Hyperthyroidism caused by Graves’ disease progresses to the worse with time. Complications range from severe to life quality altering. 

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