In the case of thyroid hormone resistance, enough thyroid hormones are produced, but they cannot adequately affect the pituitary gland or the peripheral organs. The cause is a genetic defect in thyroid hormone receptors. The clinical picture of thyroid hormone resistance is very variable.
What is thyroid hormone resistance?
In the case of thyroid hormone resistance, the two thyroid hormones thyroxine (T4) and triiodothyroxine (T3) are not sufficiently effective. There are two forms of thyroid hormone resistance. On the one hand there is the general peripheral thyroid hormone resistance and on the other hand the isolated thyroid hormone resistance on the pituitary gland or the other organs. Thyroid hormones are produced in the follicular epithelial cells of the thyroid gland. See bittranslators for About Intervertebral Disc Degeneration.
They are represented by two hormones such as thyroxine (T4) or the more effective triiodothyroxine (T3). Both hormones regulate energy metabolism and cell growth. Therefore they are essential to life. They act via receptors on the pituitary gland and other peripheral organs. They have no effect on the brain, spleen and testicles, but increase the metabolism in all other organs and tissues.
They also influence the activity of the endocrine glands. They exercise this influence via the pituitary gland. They regulate the sugar metabolism by increasing insulin production and stimulating the activity of the adrenal glands. It is also known to have an effect on sex hormones.
Causes
So-called receptors are necessary for the activity of the thyroid hormones. The molecules dock onto these receptors and can thus develop their effectiveness. However, if the receptors are defective or insufficiently effective due to a mutation, there is thyroid hormone resistance despite sufficient hormone concentration. The mutation is usually inherited in an autosomal dominant manner.
Since the thyroid hormones cannot sufficiently bind to the receptors, their effectiveness is limited. Due to this low effectiveness, the body produces even more thyroid hormones. Therefore, with thyroid hormone resistance, the concentration of thyroid hormones is increased. Effectively, the function can be normal, increased or even decreased with the increased hormone concentration.
This results in a variable clinical picture, which can only be treated individually. The hormone thyrotropin (TSH) is normal or slightly elevated. TSH is also known as thyroid stimulating hormone. It is produced in the anterior pituitary gland and is responsible for regulating thyroid hormone production. When thyroid hormone concentrations are low, the concentration of thyrotropin, which stimulates the thyroid gland to produce hormones, increases.
If the thyroid hormone concentration increases, the concentration of TSH decreases. Subsequently, the concentration of thyroid hormones also decreases. This regulatory mechanism no longer works properly in thyroid hormone resistance. Even with the additional administration of thyroid hormones, the concentration of TSH does not decrease, since their effectiveness does not increase further despite hormone administration.
Two different genes encode the thyroid receptors. One is the THRA gene from chromosome 17 and the other is the THRB gene from chromosome 3. Mutations in one of the two genes or in both genes can lead to a defect in the thyroid hormone receptors, which leads to thyroid hormone resistance.
Symptoms, Ailments & Signs
The manifestation of thyroid hormone resistance varies. It depends on whether the thyroid gland is underactive, overactive or even normal. The effectiveness of the thyroid hormones also depends on the severity of the defect in the receptors. Patients usually develop goiter.
Hyperactivity, learning and hearing disorders, cardiac arrhythmias or developmental disorders of the central nervous system and the skeleton are often present. Even within families, the symptoms of the disease can vary. A general resistance and a pituitary resistance can be distinguished. In the case of general resistance, the thyroid function can be normal despite increased hormone levels.
However, hypothyroidism is also found. In the case of pituitary thyroid hormone resistance, TSH production increases because the control circuit does not function despite increased thyroid values. Elevated TSH levels, however, produce even more elevated thyroid hormone levels, which can then affect the other organs and cause hyperthyroidism.
Diagnosis & course of disease
To diagnose thyroid hormone resistance, the thyroid hormones and TSH levels are examined. Both thyroid hormone levels are elevated. TSH is either normal or moderately elevated. When T4 is administered, there is no reduction in TSH levels. With a normal thyroid hormone effect, the administration of thyroid hormones should immediately lead to a decrease in the TSH concentration.
Complications
The symptoms and complications of thyroid hormone resistance depend relatively heavily on whether the thyroid gland is underactive or overactive. However, both malfunctions have a very negative effect on everyday life and the quality of life of those affected, so that treatment is necessary. In most cases, this leads to the development of a goiter.
Furthermore, most of those affected also suffer from hyperactivity and thus from concentration disorders. This can have a very negative effect on learning behavior, especially in children, and may lead to impaired development. Heart disorders can also occur due to thyroid hormone resistance and must be examined.
The malfunctioning of the thyroid usually has a negative effect on the internal organs, so that these can also be damaged. Thyroid hormone resistance is usually treated without complications. Those affected depend on the intake of hormones.
In this way, the symptoms can be completely limited and alleviated. In most cases, however, patients are dependent on lifelong therapy. With early diagnosis and successful treatment, the patient’s life expectancy is not negatively affected by this disease.
When should you go to the doctor?
The symptoms of thyroid hormone resistance are individual and cannot be precisely defined. Basically, a doctor is needed as soon as the person concerned experiences suffering in everyday life, feels unwell for a long time or changes appear that trigger a deterioration in the quality of life.
If you have problems coping with everyday life, a decrease in mental performance, restlessness or hyperactivity, a doctor should clarify the cause of the symptoms. If there are learning deficits, if the usual requirements can no longer be met or if there are changes in mood, the person concerned needs help. Weight fluctuations, libido disorders or mental irregularities indicate hormonal imbalances in the organism. Impure skin, brittle nails and hair growth disorders are further signs of health problems.
Swelling in the area of the thyroid indicates an enlargement of the organ and should be clarified. If the affected person can perceive changes through their own touch, a doctor should be consulted. If you have a feeling of tightness in your throat or chest, if you have problems swallowing or if you have problems breathing, you should be examined and treated. Enlargement of the thyroid gland can cause shortness of breath, which can lead to anxiety. In addition, the oxygen supply of the organism is reduced, which results in increased cardiac activity. A doctor should therefore also be consulted in the event of heart palpitations.
Treatment & Therapy
Therapy for thyroid hormone resistance depends on the symptoms that occur. If there is general thyroid hormone resistance, thyroid function may be normal. Then no therapy is necessary. If the value is too low, T4 must be given in a concentration that is necessary for normal thyroid function. This is different in each individual case.
In the case of pituitary thyroid hormone resistance, only the pituitary gland is affected by the resistance. All other organs react normally to the thyroid hormones. Since the TSH value is increased here due to the pituitary disruption of the hormone control circuit, the thyroid hormone values are also increased.
All of the organs affected by the thyroid hormones, apart from the pituitary gland, react to the increased levels in the form of hyperthyroidism. In these cases, an attempt is first made to reduce the TSH levels. If that doesn’t work, complete removal of the thyroid is often the only alternative. Subsequent substitution therapy is influenced by the clinical picture.
Prevention
Since the inheritance of thyroid hormone resistance is usually autosomal dominant, people who are affected should seek human genetic counseling if they wish to have children. With this form of inheritance, 50 percent of the disease is transmitted to the offspring. However, autosomal recessive inheritance was also discovered, which should be uncovered by human genetic studies.
Aftercare
Thyroid hormone resistance is usually congenital. The problems can vary, as the target cells do not respond adequately to the thyroid hormones that are actually present. Since thyroid hormone resistance is not generally regarded as a disease that heals after acute treatment, it cannot be assumed that this is purely aftercare.
Follow-up care combined with treatment is usually lifelong. However, the effects may change or alternate. Regular visits to a specialist, in this case an endocrinologist, are therefore essential. Depending on the course of the disease, tests of certain blood parameters as well as sonographic imaging of the thyroid itself are essential at specified intervals, as goiter can occur.
Depending on the course of the disease, a certain lifestyle or diet may be indicated for the patient. This can refer in particular to the omission of iodine. The endocrinologist will guide you accordingly and, if necessary, refer you to nutritional advice. As regular lifelong treatment can be assumed, no follow-up care can be provided after healing has taken place. This would only be conceivable in isolated cases of later-onset pituitary diseases. Then the aftercare refers to the control of the hormone levels and the necessary medication to support a normal metabolism.
You can do that yourself
In the case of thyroid hormone resistance, there are no self-help options for curing the disease. The symptoms of this disorder are manifold, but can be partially alleviated by targeted training or exercise sessions.
In the case of an existing learning disorder, there is the possibility of continuously working on an improvement through therapies tailored to the needs of the patient, even without a doctor. An individual training plan is created together with a therapist, which can be expanded and continued independently at home.
If the patient is a child, legal guardians and relatives should help to complete the learning training. This improves the patient’s quality of life and social cohesion. Since concentration disorders can occur, the exercise units must be tailored to the patient’s abilities and needs. Overwhelmed situations should be avoided. In addition, achieved goals and successes are to be praised and valued accordingly.
In order to prevent psychological stress, the patient should be informed sufficiently and early on about their physical and mental abnormalities. Open discussions and the clarification of existing questions can help to better cope with the disease in everyday life. In addition, a comprehensive explanation of the further development over the lifespan is advisable.
