Dosage

L-thyroxine fulfils the same functions as the body’s own thyroid hormones. Consequently, L-thyroxine is used when the thyroid gland no longer produces enough hormones on its own. The amount of hormones that is not produced enough must therefore be replaced by the corresponding amount of L-thyroxine.

For this reason, the dosage of L-thyroxine must be adjusted individually according to the type and severity of the disease. In addition, the amount of hormones required by the body and thus the dose of L-thyroxine varies according to the age, height and weight of the patient. To find out the amount of L-thyroxine needed, a blood test by a doctor is necessary.

This must be repeated as a control examination during the course of therapy. In this way, the doctor can always determine and adjust the dosage exactly for the respective patient. Once this is done, the full dose should be taken one day on an empty stomach, at least half an hour before the first meal.

Generally, a dose of 25-50 micrograms per day is started. This dose is then increased step by step, increasing each 25 – 50 micrograms within a month. This is done until the appropriate dosage is reached.

If the thyroid gland is congenitally underactive, the average dose is 100 – 200 micrograms. The same amount is also used for Hashimoto’s thyroiditis and must be taken mostly until the end of life. An underfunction can also result from thyroid surgery or treatment.

If the thyroid gland has been completely removed, for example due to a tumor, no thyroid hormones can be produced by the body. In this case, the entire amount of the hormones required by the body must be replaced by L-thyroxine. A dosage of up to 300 micrograms per day is used for this purpose.

This is usually administered for life. If only part of the thyroid gland is affected, for example by a benign lump, the maximum dosage required is 200 micrograms per day. If this recedes, the drug can be discontinued in some cases after six months to a few years.

There are also drugs that reduce the function of the thyroid gland. They are called thyrostatics and are used to treat hyperthyroidism. Although it may seem paradoxical at first, a small amount of L-thyroxine can also be used in this therapy.

In this way, the optimal hormone level in the blood can be precisely adjusted, even if the thyroid gland is severely slowed down. A dose of 50 – 100 micrograms per day is usually prescribed here. This is taken for the same period of time as the thyrostatics.

When taking L-thyroxine during sports, the dosage does not need to be adjusted. It should be noted that taking L-thyroxine increases the drive of metabolism and heart. As a result, the training can be perceived as easier.

However, it should be noted that L-thyroxine can only increase the body’s performance if there is a lack of thyroid hormones. If a normal hormone level is present, the metabolism is set in motion so strongly by the intake of further medication that proteins in muscles are broken down and heart rhythm disturbances can occur. Furthermore, the correct dosage of L-thyroxine during pregnancy is very important.

When dosed correctly, there are no known side effects that could harm the child. During pregnancy, the increased amount of hormones, such as estrogen in the mother’s blood, may also increase the amount of thyroid hormones needed. For this reason, an even tighter control of the hormones in the blood should be carried out by the doctor during pregnancy.

In this way, the dosage can always be adjusted precisely and the child protected. The effect of L-thyroxine influences the body in many ways and has a particular influence on the metabolism and heart rhythm. The body adapts to the new thyroid hormone level during treatment.

Therefore, a sudden withdrawal of L-thyroxine can be very dangerous. A reduction of the dose should therefore not be made without consulting the doctor.If serious side effects occur, an adjustment of the dosage should be discussed with the doctor before the next time the medication is taken. In addition, the medication must be taken regularly to keep the amount of thyroid hormones in the blood constant and thus achieve the desired effect by treating with L-thyroxine.

Therefore L-thyroxine should not be discontinued even if symptoms improve. When taking L-thyroxine, especially if the dose is increased too quickly at the beginning of treatment, typical symptoms of hyperthyroidism may occur, which manifest themselves with the following symptoms: Fever and vomiting may also occur as atypical symptoms. Hypersensitivity to L-thyroxine may also occur, leading to allergic reactions on the skin and in the respiratory tract.

Palpitations
Cardiac arrhythmias
Tightness and pain in the chest
Blood pressure increase
Heat sensation
Trembling (Tremor)
Inner restlessness
Diarrhea, weight loss, increased appetite
Headaches

L-thyroxine has the same effect in the body as the body’s own thyroid hormones. Among other things, these activate the work of the digestive tract. This promotes the movement of the intestines and thus the movement of food.

If the thyroid hormones are present in too high a quantity or in quantities that are unusual for the body, the drive of the intestine can be increased so much that diarrhoea occurs. For this reason, this side effect can occur even if the correct dosage is taken at the beginning of the intake of L-thyroxine. A significant effect of the thyroid hormones and thus also of L-thyroxine is the increase in the body’s willingness to be active and the associated increase in body temperature.

In doing so, the entire metabolism is set in motion to provide energy. Therefore the body burns more calories and reduces reserves. For this reason, taking L-thyroxine can result in weight loss.

Nevertheless, the drug should not be misused for this purpose, especially in people with healthy thyroid glands. The reason for this is that the increase in activity mainly affects the heart and can lead to consequences ranging from heart stumbling to sudden cardiac death. L-thyroxine increases the body’s willingness to be active and promotes metabolic processes.

In order to provide enough energy, carbohydrates and fats are burned more often. In order to give the body additional strength to become active, low doses of L-thyroxine lead to the building of muscle. However, if the dose of L-thyroxine is very high, the body has to provide even more energy.

Energy reserves in the muscle can then be used for this purpose. This is broken down and the released muscle proteins can now be used as energy suppliers. This can manifest itself in the form of muscle pain as a side effect of L-thyroxine.

For this reason, muscle pain that occurs without an obvious cause such as excessive exercise should be discussed with a doctor. The doctor may adjust the dosage of L-thyroxine if necessary. Loss of libido is not a known side effect of L-thyroxine.

However, there may be a correlation between the amount of thyroid hormones in the blood and the desire for sex. With hypothyroidism, the drive of the body is severely restricted and affected persons often feel slowed down. This can sometimes be accompanied by a loss of libido, which can be improved by the right hormone level. In addition, excessive doses of L-thyroxine should also be avoided. This can lead to restlessness, cardiac arrhythmia and circulatory problems and can also influence sexual desire.