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According to the World Health Organization (WHO), in the adult population, the prevalence of hypothyroidism ranges between 0.6 and 12 per 1000 women and between 1.3 and 4.0 per 1000 men investigated, although the prevalence is higher in surveys of the elderly for studies conducted in northern Europe, Japan and the USA.
The incidence of congenital hypothyroidism has nearly doubled over the past two decades in several countries studied including the USA, Western Australia, Italy, northern UK, and Greece.
Hypothyroidism is defined as a disorder in the thyroid gland that is manifested as a decreased activity of the gland that may affect the entire body functions.
There are many causes of hypothyroidism such as autoimmune diseases such as rheumatoid arthritis, pituitary disorders such as hypopituitarism, and congenital diseases such as Down’s syndrome.
Hypothyroidism tends to run in families and is more common in women than in men. Some autoimmune diseases and insufficient or excess amounts of dietary iodine increase the risk of developing hypothyroidism. Common signs and symptoms of hypothyroidism are fatigue, weight gain, and a puffy face.
The thyroid gland is an organ located in the front of the neck that releases thyroxine (T4) and triiodothyronine (T3) hormones. These hormones play an important role of how the whole body functions. In hypothyroidism, the thyroid gland does not make enough thyroid hormones.
Most people who are diagnosed with hypothyroidism by physical examination and blood tests are given hormone replacement tablets to restore adequate hormone levels. These tablets are known as levothyroxine. Combination therapy that uses levothyroxine and triiodothyronine (T3) together could also be used.
If it is not treated, hypothyroidism can lead to complications including goiter, heart disease, mental health problems, myxedema, and infertility. However, the prevention of developing hypothyroidism can be done by maintained iodine level within the normal level in the body .
Hypothyroidism, which is also known as an underactive thyroid is a condition by which the thyroid gland is unable to make enough hormones.
Hypothyroidism occurs when not enough amounts of the thyroid hormones needed to control metabolism are produced. Hypothyroidism can be divided into three subtypes:
1-Primary hypothyroidism
It is a problem in the thyroid gland that is represented by the inability of the thyroid gland to produce hormones.
2-Secondary hypothyroidism
In secondary hypothyroidism, the pituitary gland fails to produce enough thyroid stimulating hormone (TSH) which leads to reduced production of the thyroid hormones (T3 and T4) by the thyroid gland.
3-Tertiary hypothyroidism
In tertiary hypothyroidism, problems with the hypothalamus cause insufficient production of thyrotropin release hormone (TRH). When TRH levels are low, the pituitary gland does not produce enough TSH, leading to insufficient stimulation of the thyroid gland to produce T3 and T4.
An improper functioning of the thyroid gland or an improper stimulation of the thyroid gland by the hypothalamus or pituitary gland leads to hypothyroidism. A number of causes are responsible for hypothyroidism including:
1-Autoimmune disease
Thyroid gland cells and their enzymes can be mistaken for invading infections and are attacked by the immune system in some people's bodies. This leads to less thyroid cells and enzymes that may not be sufficient to make enough thyroid hormone. For example, Hashimoto's disease, known also as Hashimoto's thyroiditis, is one of the most common autoimmune reactions that cause hypothyroidism.
2- Treatment for hyperthyroidism
Usually the treatment of hyperthyroidism with radioactive iodine or anti-thyroid medications destroys the cells of the thyroid gland which by its role leads to decreasing the production of T4 and can result in permanent hypothyroidism.
3- Thyroid surgery
When the whole of or a large portion of the thyroid gland is removed, this may decrease hormone production and may lead to hypothyroidism.
4- Radiation therapy
The thyroid gland can be destroyed when radiation is used to treat cancers of the head and neck, and may result in hypothyroidism.
5- Medications
A number of medications can interfere with the production of the thyroid hormones. These include:
It is a medication that is sometimes used to treat certain mental health conditions, including depression and bipolar disorder.
It is a medication sometimes used to treat irregular heartbeats which is also knowns as arrhythmias.
A class of medication that is sometimes used to treat certain types of cancer and hepatitis C.
6- Congenital hypothyroidism
It is uncommon, where some babies are born with a defective thyroid gland or no thyroid gland. Unknown reasons cause the improper development of the thyroid gland in the womb, but some children have an inherited form of this disorder. Routine screening soon after birth reveals infants with congenital hypothyroidism who appear normal at birth .
7- Pituitary or hypothalamus disorders
The pituitary gland is located at the base of the brain and is responsible for regulating the thyroid gland. Disorders of the hypothalamus or the pituitary gland can cause hypothyroidism since they are responsible for changing the levels of the thyroid hormones.
8- Pregnancy
In pregnancy, some women produce antibodies against their own thyroid gland which leads to developing hypothyroidism during or after pregnancy. If left untreated, hypothyroidism increases the risk of miscarriage, premature delivery and preeclampsia, characterized by a high level of protein in urine and a high blood pressure in women who have not had high blood pressure before.
9- Too much or too little iodine
Iodine should be in the correct amount in order to maintain the thyroid hormone production in balance. Taking in too much iodine or low amounts of iodine can lead to hypothyroidism.
Many factors contribute to an increased risk of developing hypothyroidism including:
1-Gender
Hypothyroidism is more common in women than in men, specifically women are 10 times more likely to get hypothyroidism.
2-Age
Although all ages can be affected, hypothyroidism is more common in people aged 50 and increases with age.
3- Medical condition
Having certain medical conditions also increases the risk of developing hypothyroidism. These medical conditions include autoimmune disease such as rheumatoid arthritis, polycystic ovarian syndrome, anorexia or bulimia, gout; a complex form of arthritis, Addison’s disease; where insufficient amounts of certain hormones are produced by the adrenal glands, myasthenia gravis; occurs from the breakdown in the normal communication between nerves and muscles, and Turner syndrome which is a chromosomal disorder that affects females.
4- Family history
People with a family history of hypothyroidism are at a higher risk of developing hypothyroidism. Thyroid diseases often skip generation, for example a person who is sick might have healthy parents. Inherited tendencies of thyroid diseases could vary from one person to another, from never getting a disease to having a severe case.
5- Smoking
Smokers have an increased risk of developing hypothyroidism, in addition smoking can provoke existing symptoms of the thyroid disease especially on the arteries and heart. Autoimmune Hashimoto's thyroiditis and postpartum thyroiditis have a significant increase in the risk of getting thyroid disease.
The thyroid is a small, butterfly-shaped gland situated at the base of the front of the neck, whose hormones regulate the way our bodies use energy, i.e. almost every organ is affected by the thyroid hormones, even the way the heart beats.
The functions of the body are highly governed by the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). 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 protein production.
Signals from the hypothalamus to the pituitary gland makes the latter produce thyroid-stimulating hormone (TSH). The quantity of (TSH) released depends on the quantity of) T4( and) T3( found in the blood. An inverse relation correlates (TSH) to (T3) and (T4), i.e when one is low the other is high. When the thyroid gland receives (TSH), it regulates the production of hormones. When not enough amounts of (T4) and (T3) are produced, hypothyroidism occurs.
The symptoms may vary from one individual to another depending on the severity of the hormones deficiency.
These include:
1- Fatigue.
2- Weight gain.
3- Puffy face.
4-Trouble tolerating cold.
5- Joint pain.
6- Constipation.
7- Dry skin.
8- Dry, thinning hair.
9- Decreased sweating.
10- Irregular menstrual periods.
11- Fertility problems.
12- Depression.
13- Slowed heart rate.
14- Enlarged thyroid (goiter).
15- Impaired memory.
16- Hoarseness.
17- Muscle weakness.
18- Elevated blood cholesterol levels.
19- Muscle aches, tenderness and stiffness.
20- High blood pressure.
21- Shortness of breath when exercising.
22- Yellowish skin.
23- Enlarged tongue.
Signs and symptoms of hypothyroidism in infants
These signs appear in infants with hyperthyroidism:
Severe physical and mental retardation are the possible results of untreated hypothyroidism in infants, even in mild cases.
1-Yellowing of the skin and whites of the eyes (jaundice).
2-Frequent choking.
3- Large, protruding tongue.
4- Puffy face.
Furthermore, symptoms in infants who are likely to have feeding problems and may fail to grow and develop normally as the disease progresses include:
1-Constipation.
2-Poor muscle tone.
3-Excessive sleepiness.
The symptoms in children and teens who have hypothyroidism include:
1-Poor growth, resulting in short stature.
2-Delayed development of permanent teeth.
3-Delayed puberty.
Elderly people with hypothyroidism may develop memory problems and depression.
Symptoms, signs, and several factors are taken into consideration when hypothyroidism is diagnosed. The diagnosis of hypothyroidism includes:
1- Physical Examination
Physical examination is conducted in order to check for signs and symptoms that are associated with hypothyroidism. Many symptoms of hypothyroidism are similar to those of other diseases, so a diagnoses for hypothyroidism based solely on symptoms cannot be done.
2-Blood test
A hormone produced by the pituitary gland that stimulates the thyroid gland to produce hormones.
One of the main thyroid hormones.
A low level of thyroxine (T4) and a high level of (TSH) indicate hypothyroidism.
Other tests may help diagnosis hypothyroidism. They are as the following:
1-Cholesterol level.
2-Complete blood count (CBC).
3-Liver enzymes.
4-Prolactin.
5-Sodium.
6-Cortisol.
Treatment of hypothyroidism includes many ways which are listed below:
1-Hormone replacement tablets
Daily hormone replacement tablets called levothyroxine, which is an oral medication that restores adequate hormone levels, leading to the reversal of the signs and symptoms of hypothyroidism. It is considered the most commonly used medicine and is usually a lifelong treatment. Treatment may start on a very small dose if the patient has a heart disease or is older, and the appropriate dose of hormone replacement tablets should be used to avoid side effects.
2-Combination therapy
Combining both levothyroxine and triiodothyronine (T3) together is not routinely used due to lack of evidence that proves its efficiency rather than using levothyroxine alone.
This treatment is recommended in cases where a person has a history of thyroid cancer and with a high possibility of reoccurring.
When untreated, signs and symptoms can gradually become more severe and may lead to a number of health problems such as:
1-Goiter
A goiter is an abnormal enlargement of the thyroid gland that is mainly caused by Hashimoto's thyroiditis. When the bodies of people with hypothyroidism stimulate the gland to produce more thyroid hormones, they can develop goiters. A large goiter can affect the appearance and may interfere with swallowing or breathing.
2-Heart problems
An increased risk of heart diseases is related to the reason that people with hypothyroidism may have high levels of low-density lipoprotein cholesterol. High cholesterol can cause fatty deposits to build up in arteries, and restrict the flow of the blood. An enlarged heart and heart failure can be a result of hypothyroidism.
3-Mental health issues
Early depression and a slowed mental functioning can be caused by hypothyroidism.
4-Peripheral neuropathy
It is the damage of the nerves that carry information from the brain and spinal cord to the rest of body. Signs and symptoms of peripheral neuropathy may include pain, numbness, tingling in the area affected by the nerve damage, and muscle weakness or loss of muscle control.
5-Myxedema
It is a rare, life-threatening condition that occurs as hypothyroidism progresses to its advanced stages as a result of low levels of thyroid hormones produced. Intense cold intolerance, unconsciousness, and drowsiness followed by profound lethargy are the symptoms of myxedema. Sedatives, infections or other stress on the body can trigger a myxedema coma.
6-Infertility
Low levels of the thyroid hormone can interfere with ovulation and decrease a woman's chances of conceiving.
7-Pregnancy complications
During pregnancy, hypothyroidism should be treated, otherwise a number of pregnancy problems may occur including:
These problems can be avoided with treatment under the guidance of a specialist in hormone disorders (an endocrinologist). However, if this condition is diagnosed within the first few months of life, the chances of normal development are excellent.
The level of iodine in the body should be maintained within the normal level to reduce risk of development of hypothyroidism.
The most common cause of hypothyroidism is Hashimoto’s thyroiditis. A gradual development in adults usually occurs that leads to a slow destruction of the tissue of the thyroid gland. Increasing hormone production by the remaining tissue can compensate for the loss, in order to keep the body’s levels stable. When a large portion of the thyroid tissue has been destroyed, not enough hormones can be produced, which in turn causes the symptoms of hypothyroidism.
Tablets can easily replace the lack of thyroid hormones in the body. This can stabilize the metabolism and make the symptoms disappear. When left untreated, hypothyroidism may cause a number of problems such as goiter and heart problems. In the rarest of cases, it can even lead to a myxedema coma.
According to the World Health Organization (WHO), in the adult population, the prevalence of hypothyroidism ranges between 0.6 and 12 per 1000 women and between 1.3 and 4.0 per 1000 men investigated, although the prevalence is higher in surveys of the elderly for studies conducted in northern Europe, Japan and the USA.
The incidence of congenital hypothyroidism has nearly doubled over the past two decades in several countries studied including the USA, Western Australia, Italy, northern UK, and Greece.
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