Conditions Underactive thyroid

An underactive thyroid (hypothyroidism) occurs when the thyroid gland does not produce enough hormones. The thyroid gland (thyreoidea) is a vital organ. It produces hormones that regulate metabolic processes and keep them in balance. The thyroid hormones control a large number of processes in the human body.

An underactive thyroid slows down the metabolism. As a result, it can cause general symptoms such as fatigue, listlessness, skin changes, or constipation.

Most cases of underactive thyroid are caused by a chronically inflamed thyroid gland. The symptoms usually disappear through the daily intake of tablets containing thyroid hormones.

A lack of thyroid hormones slows down the metabolism. This can affect many parts of the body and cause a wide range of symptoms.

General symptoms include:

• weakness and tiredness
• low heart rate
• shortness of breath

psychological problems may also occur, such as:

• concentration and memory problems
• lethargy
• depression or other mental health issues

Physical changes may also occur, such as:

• dry skin and puffiness, especially on the face
• dry hair, hair loss
• mild to moderate weight gain
• enlarged thyroid, also referred to as goiter or struma
• a low-pitched, hoarse voice
• an enlarged tongue
• constipation
• severe or irregular menstrual bleeding or menstrual cycle disorders, reduced fertility
• erectile dysfunction
• impaired hearing

There are also symptoms that affect the body as a whole, such as:

• feeling cold and sensitivity to cold
• muscle pain or joint pain
• tingling and numbness
• slower reflexes

Many of these symptoms may have other causes too. In older people in particular, an underactive thyroid may be mistaken for age-related changes. This may happen, for example, with people in the initial stages of dementia.

An underactive thyroid may have a range of causes. Conditions and factors that can lead to a deficiency in thyroid hormones include:

• inflammation of the thyroid gland
• thyroid gland removal or radiotherapy
• severe iodine deficiency
• medication
• congenital hypothyroidism

Inflammation of the thyroid gland

In people with Hashimoto’s thyroiditis, the thyroid gland is chronically inflamed. This auto-immune disease is the most common cause of an underactive thyroid in this country. An infection can also trigger an inflammation. Sometimes the cause remains unclear.

Thyroid gland removal or radiotherapy

Treatment of some conditions, such as an overactive thyroid or thyroid cancer, involves exposing the thyroid gland to radiation or surgery to remove it entirely or in part. This means that not enough thyroid hormones are produced, or sometimes none at all.

Severe iodine deficiency

Iodine is an important trace element. The body needs it to produce the thyroid hormones. As the body cannot produce iodine itself, it must absorb it from food, e.g via saltwater fish, milk, dairy products and eggs as well as through the use of iodized table salt. An underactive thyroid may develop if the body consistently fails to get enough iodine. However, this is very rarely the case in industrialized countries today.

Medication

Certain medications, such as antidepressants containing the active substance lithium, can inhibit the production of thyroid hormones. Some drugs used to treat an overactive thyroid can also inhibit the production of thyroid hormones. If the dosage is too high, this can cause an underactive thyroid.

Congenital hypothyroidism

In rare cases, an underactive thyroid is genetically determined, i.e. present at birth. However, it can also be triggered if a pregnant woman does not consume very much iodine or her immune system forms antibodies against thyroid tissue.

In each of the cases described above, the thyroid gland itself is affected. This is known as primary hypothyroidism. However, in rare cases, an underactive thyroid can also be caused by abnormal function of the pituitary gland or the hypothalamus. The pituitary gland and hypothalamus produce hormones that control hormone production in the thyroid gland. This means that a thyroid gland may itself be healthy but may no longer be controlled correctly so that it fails to produce enough hormones. Doctors refer to this as central hypothyroidism.

In countries like Germany, around 5 percent of people have an underactive thyroid. It more commonly affects women and older people. An underactive thyroid is congenital in approximately 1 out of 3,400 newborns.

How an underactive thyroid progresses varies depending on what causes it. Most adults affected have an inflamed thyroid gland. This normally causes a gradual decomposition of the thyroid tissue. An underactive thyroid often develops insidiously and can remain undetected for a long time. This is because for a certain period of time, the remaining thyroid tissue can compensate for the tissue that is lost by increasing its production of hormones so that the body still has an adequate supply.

However, as the condition progresses, more and more tissue is lost, until the gland can no longer produce enough hormones. Symptoms then appear. If the underactive thyroid is left untreated, this may cause circulatory problems, for instance.

The missing thyroid hormones can easily be replaced by taking tablets. This restores normal metabolism and the symptoms disappear. Sometimes, the thyroid heals by itself – for example, when the inflammation clears up.

You cannot prevent an underactive thyroid, with one exception: adequate iodine intake prevents an underactive thyroid caused by iodine deficiency. This can be done by consuming milk or dairy products daily and by regularly eating salt-water fish and using iodized salt. There are also certain food supplements that contain iodine.

A normally functioning thyroid gland is particularly important for babies and children. An underactive thyroid can have very adverse effects on physical and mental development.

This is why the TSH level of newborns is routinely determined as part of screening tests. TSH stands for thyroid-stimulating hormone. This hormone is produced in the pituitary gland and stimulates the thyroid gland to produce hormones. An elevated TSH reading is an indicator of an underactive thyroid gland. If there is an abnormal result, the thyroid hormone levels are also measured.

To diagnose underactive thyroid, the doctor begins by asking about the symptoms. This is followed by a physical exam (palpation) of the thyroid gland. If there are any indications of underactive thyroid, a blood test is required because many of the symptoms can also have alternative causes. The blood test measures thyroid hormone and TSH levels.

TSH is a hormone produced in the pituitary gland to stimulate the production of thyroid hormones. Slightly elevated TSH levels may be the first sign of an incipient underactive thyroid. If the thyroid gland becomes weaker, the body produces more TSH to boost its activity. At a certain point, however, this is no longer sufficient and the thyroid gland no longer releases enough hormones into the bloodstream. This can also be detected in a blood test.

The treatment of underactive thyroid seeks to compensate for the hormone deficit. To this end, the missing thyroid hormone thyroxine is replaced by a medication that is converted into the hormone within the body. The active ingredient is also referred to as levothyroxine or L-thyroxine. The drug restores hormone levels to normal so that symptoms usually clear up entirely. Depending on the cause, treatment of an underactive thyroid is either temporary or lifelong.

There are virtually no side effects provided the right dose is given. The dosage is based on body weight. A dose that is too high can lead to heart problems. The dose is therefore regularly reviewed in the first few weeks and adjusted if necessary. Later, it is usually sufficient to check the levels once a year.

L-thyroxine is taken once a day. It is often recommended to take the tablet with a glass of water in the morning, half an hour before breakfast.

Experts disagree on whether or not a subclinical underactive thyroid should be treated.

For more detailed information about whether and when a subclinical underactive thyroid should be treated, visit gesundheitsinformation.de.