Hypothyroidism is a lack of thyroid hormones, which slows down the metabolism and can lead to various complaints such as fatigue, sensitivity to cold, constipation and muscle weakness. An underactive thyroid is usually treated by the targeted administration of thyroid hormones in order to stabilise the hormone balance.
The thyroid at a glance
The thyroid is a small, butterfly-shaped organ located in the neck area, and is responsible for the production of vital hormones. Among other things, these hormones control the body’s metabolism and influence growth and development. If the thyroid does not produce enough thyroid hormones, this is known as an underactive thyroid (hypothyroidism). This hormone deficiency can affect the metabolism and lead to various symptoms such as fatigue, sensitivity to cold and constipation.
However, if the thyroid gland produces too many hormones, this is known as an overactive thyroid (hyperthyroidism), which speeds up the metabolism and can cause symptoms such as nervousness, rapid heartbeat and unwanted weight loss.
What is the thyroid important for?
The thyroid hormones regulate heart rate, digestion, mental state and body temperature. The balance of these hormones is essential for health and everyday wellbeing. A stable hormone level is crucial for the functioning of these systems. Thyroid dysfunction can affect the cardiovascular system, metabolism and mental health. Therefore, the thyroid gland is essential for physical and mental well being.
Definition and explanation of hypothyroidism
An underactive thyroid is one of the most common hormonal illnesses. About one in 3 000 to 4 000 newborns is affected by congenital hypothyroidism. However, the disease occurs more frequently later in life (acquired hypothyroidism) and the incidence increases with age. In addition, women are more often affected by an underactive thyroid than men.
The thyroid produces three critical hormones that are essential for the regulation of various bodily functions: An underactive thyroid occurs when the thyroid does not produce enough of these hormones:
Thyroxine (T4)
The main product of the thyroid gland, which is produced in large quantities. It plays a central role in regulating metabolism and influences growth and development.
Triiodothyronine (T3)
This hormone is more active than T4 and has a faster impact on the body. It is mainly produced by converting T4 into T3 in peripheral tissues.
Calcitonin
Is involved in regulating calcium and phosphate levels in the blood and therefore plays an important role in bone health.
Causes of hypothyroidism
Hypothyroidism can occur in different forms, each of which is caused by differing factors. Some forms are caused directly by disorders of the thyroid gland itself, while others are caused by problems in higher control centres, such as the pituitary gland or the hypothalamus. The distinction between the cause is crucial, as it influences the diagnosis and treatment. Medicine classifies three main types of hypothyroidism: primary, secondary and tertiary hypothyroidism.
Primary hypothyroidism
Primary hypothyroidism results directly from problems with the thyroid gland itself and can be caused by various factors that directly affect thyroid function. One common cause is autoimmune thyroid inflammation, also known as Hashimoto’s thyroiditis, in which the immune system mistakenly attacks and damages thyroid cells. Other causes include a low-iodine diet, thyroid surgery, radiation in the neck area or congenital thyroid abnormalities and disorders.
Secondary hypothyroidism
Secondary hypothyroidism is often the result of a dysfunction of the pituitary gland, which stimulates the thyroid gland, and occurs when the pituitary does not produce enough thyrotropin (TSH) for the thyroid gland to produce hormones. Secondary hyperthyroidism can be caused by tumours of the pituitary gland or hypothalamus, head injuries, serious illnesses, radiotherapy to the head area, genetic factors and certain medications that affect pituitary function.
Tertiary hypothyroidism
Tertiary hypothyroidism is a rare illness that starts from a disorder in the hypothalamus and can be caused by tumour, trauma or inflammation in the hypothalamus. Genetic diseases or defects in the signalling pathways between the hypothalamus, pituitary gland and thyroid can also trigger this form of hypothyroidism. It often occurs when the hypothalamus does not produce enough TRH, leading to reduced TSH levels by the pituitary gland and as a result, reduced hormone production.
Symptoms of hypothyroidism
The symptoms of hypothyroidism differ significantly between children, adolescents and adults, as the effects of thyroid hormone deficiency vary depending on the stage of life.
Symptoms in adults
An underactive thyroid in adults is manifested by fatigue, cold intolerance, weight gain despite unchanged eating habits, dry skin, hair loss, slowing heart rate, cognitive impairment such as memory problems or reduced ability to concentrate.
Symptoms in adolescents
Symptoms of an underactive thyroid function in adolescents include slow puberty development, irregular menstrual cycles in girls and general exhaustion.
Symptoms in children
Typical signs of an underactive thyroid in children are delays in physical development, restricted growth rate, late puberty, intellectual impairment or learning difficulties.
If left untreated, hypothyroidism can lead to serious health problems. It can initially manifest itself in the symptoms described, which significantly affect quality of life. In the long term, however, untreated hypothyroidism can lead to more serious complications such as heart disease, peripheral neuropathy and, in rare cases, life-threatening myxoedema coma. A slower heart rate can increase the risk of heart disease, while low metabolism can lead to a build-up of LDL cholesterol in the blood. It is therefore extremely important to diagnose and treat hypothyroidism early on to avoid more serious health problems.
Myxoedema and myxoedema coma
Hypothyroidism can lead to myxoedema, a condition characterised by swelling in the tissue. This often occurs on the face, in particular around the eyes, and sometimes on other parts of the body. It is caused by pathological deposits of carbohydrate compounds in the subcutaneous tissue.
A rare but life-threatening complication of severe hypothyroidism is myxoedema coma, which occurs mainly in older people whose disease has remained untreated for a long time. It can be triggered by additional stress, such as infection, hypothermia, heart attack or surgery. Typical symptoms of myxoedema coma are myxoedema, extreme weakness, low body temperature, slow heartbeat, shallow breathing, delayed reflexes and sleepiness to coma. A myxoedema coma is a life-threatening condition that requires immediate medical treatment.
Diagnosis of hypothyroidism
A diagnosis of an underactive thyroid requires careful evaluation to determine the exact cause and severity of the disease. Various examination methods are combined to obtain a comprehensive picture of thyroid function and possible structural changes.
History and physical examination
The doctor will ask about symptoms and perform a physical examination. They will pay particular attention to thyroid enlargement or dry, rough skin, as well as checking reflexes and heart sounds.
Blood tests (TSH, T4, T3)
Blood tests are crucial for measuring thyroid function. TSH, the hormone released by the pituitary gland, provides information on thyroid activity. If a subfunction is present, this value is elevated. The values for T4 and T3 are also measured as they directly indicate the function of the thyroid.
Ultrasound of the thyroid
An ultrasound examination (sonography) can help to better identify the cause of hypothyroidism. It allows any changes such as inflammation, cysts or nodes to be seen.
Treatment
Standard treatment usually consists of replacement therapy with synthetic thyroid hormones such as levothyroxine.
The treatment of hypothyroidism aims to compensate for the deficiency of the thyroid hormones and in doing so, to restore the body’s normal metabolic activities. This is usually done through lifelong hormone replacement therapy with levothyroxine, a synthetic thyroid hormone that is identical to the thyroxine (T4) produced by the body. Levothyroxine dosage is adjusted individually based on the patient’s age, weight, symptoms and blood values from thyroid function tests. Regular monitoring is necessary in order to adjust the dose if necessary. In some cases, and especially in secondary or tertiary hypothyroidism, treatment of the underlying cause may also be necessary.
Information on alternative and complementary treatments
Some patients may also benefit from alternative or complementary treatments. These often include a combination of lifestyle changes, such as a healthy diet and regular exercise, along with supplements containing certain nutrients that are important for optimal thyroid function. It is important to note that these methods should not be seen as a substitute for hormone replacement therapy, but rather as supportive measures.