L-thyroxine

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L-thyroxine (levothyroxine) is an artificially produced thyroid hormone. It is mainly prescribed when the thyroid gland does not produce enough thyroxine itself, for example in the case of an underactive thyroid. When dosed correctly, L-thyroxine is usually very well tolerated. However, it is important to avoid interactions with certain foods or other drugs. Read everything you need to know about L-thyroxine here.

This is how L-thyroxine works

The thyroid produces the hormones triiodothyronine (T3) and thyroxine (T4), which primarily regulate metabolic processes. If there is a hormone deficiency, these processes can no longer run smoothly. This leads to complaints such as exhaustion, tiredness or depressive moods.

L-thyroxine: effect

Artificially produced L-thyroxine closes the gap if the thyroid gland produces too little thyroxine due to illness. During the treatment, the body replenishes its thyroxine stores in order to release the active ingredient L-thyroxine as needed.

When is L-thyroxine used?

L-thyroxine is mainly used in the following cases:

• if you have an underactive thyroid (hypothyroidism)
• in the case of an enlarged thyroid gland (goiter)
• after thyroid surgery
• with overactive thyroid gland (hyperthyroidism) in combination with anti-thyroid drugs (thyroid blockers)

L-thyroxine for hypothyroidism

If the thyroid gland is underactive (hypothyroidism), the thyroid gland does not produce enough thyroxine (and triiodothyronine). This can lead to tiredness, poor performance and concentration, depressive mood, constipation, weight gain and hair loss.

The lack of hormone production in the thyroid gland can be congenital or acquired. Very often, an underactive thyroid only develops in adults in the course of life. Usually the reason is an inflammation of the organ (thyroiditis such as Hashimoto's thyroiditis). An operation or radioiodine therapy can also be the cause of hypothyroidism.

L-thyroxine for thyroid enlargement (goiter)

An enlarged thyroid gland ("goiter") usually results from a lack of iodine. Then the pituitary gland produces more of the hormone TSH, which stimulates the thyroid gland to grow. Without treatment, it can develop into a goiter.

L-thyroxine interrupts this growth process. The hormone is often prescribed together with iodine in order to treat an iodine-deficient goiter particularly effectively. This therapy can sometimes prevent the enlarged thyroid from having to be reduced in size in an operation.

L-thyroxine after thyroid surgery

If the goiter is already well advanced, surgery is often the only solution. The doctors take tissue from the thyroid gland, which can then produce correspondingly less thyroxine. In order to prevent a goiter from forming again, those affected have to regulate their hormonal balance by taking L-thyroxine.

Sometimes it is even necessary to completely remove the thyroid gland. Then the lifelong intake of artificial thyroxine is absolutely necessary, as the body can no longer produce the important active ingredient itself.

L-thyroxine is also used after surgical removal of a thyroid tumor. After the procedure, the hormone production is also often reduced, which must be compensated for by taking L-thyroxine.

L-thyroxine for hyperthyroidism

If the thyroid produces an excessive amount of hormones, it is called an overactive thyroid (hyperthyroidism). Those affected suffer, for example, from restlessness, nervousness, high blood pressure or cardiac arrhythmias. Around 90 percent of patients also develop an enlarged thyroid gland (goiter).

Hyperthyroidism is treated with so-called thyreostatics (thyroid blockers). Sometimes L-thyroxine is also prescribed.

L-thyroxine for weight loss?

People with an underactive thyroid often gain weight unintentionally without changing their eating habits. L-thyroxine compensates for the hormone deficiency and thus combats the symptoms of hypothyroidism, including weight gain.

The artificial thyroid hormone is by no means suitable as a diet product! Because if there is no disease, the thyroid produces enough thyroxine itself. If you then add L-thyroxine to the body, symptoms of an overactive thyroid can develop, such as palpitations, high blood pressure, restlessness and anxiety.

Never take L-thyroxine without a doctor's recommendation. In particular, L-thyroxine is not suitable for preventing weight gain.

L-thyroxine: alternative forms of treatment?

When dosed correctly, L-thyroxine is very well tolerated. Some patients still look for an alternative, for example because of possible interactions with other drugs.

Basically, this request should be discussed with the attending physician. Because alternatives to hormone replacement therapy with L-thyroxine are only conceivable - if at all - for very mild thyroid diseases. Then it is sometimes enough to take iodine tablets instead of L-thyroxine.

Naturopaths see other treatment options such as Schuessler salts or homeopathic substances. However, their effect has not been scientifically proven.

A deficiency of vital thyroid hormones must be treated by conventional medicine. Alternative healing methods such as homeopathy should only be used accompanying.

This is how L-thyroxine is used

L-thyroxine is usually taken in tablet form, but there are also L-thyroxine drops. Discuss with your doctor which dosage form is best for you.

L-thyroxine: dosage

The optimal hormone level varies from person to person. Therefore, the required L-thyroxine dose is also individual. The attending physician determines the dose and also the duration of treatment.

Therapy usually begins with a low dose of L-thyroxine - 25 micrograms are common initially. If this is not enough, the dose can be increased gradually to L-thyroxine 50, 75, 100 or L-thyroxine 125 micrograms. The maximum dose is 200 micrograms per day.

Treatment with L-thyroxine requires patience from the patient, because the thyroid hormone is only absorbed very slowly through the intestines. Therapy successes are therefore not apparent immediately, but only after a certain period of treatment.

During the therapy, the doctor regularly checks the blood values ​​in order to follow the thyroxine level in the blood. In this way he can see whether the current dosage is sufficient or too high or too low and must therefore be adjusted. This dose setting phase can take up to several months. However, once those affected are properly adjusted, the symptoms usually improve quickly.

Sometimes the L-thyroxine dosage needs to be readjusted over time. The individual hormone requirement depends on various factors such as age or pregnancy.

L-thyroxine: ingestion

Doctors usually recommend taking L-thyroxine once a day in the morning, about 30 minutes before breakfast, on an empty stomach. Swallow the medicine only with water. In particular, L-thyroxine intake with coffee or calcium-containing foods such as milk or yoghurt should be avoided! Because these foods bind the active ingredient and thus delay its absorption in the intestine.

The latest study results suggest that the body can utilize L-thyroxine better if it is taken in the evening instead of in the morning. Taking L-thyroxine in the evening reduces typical side effects of the therapy such as difficulty falling asleep, morning tiredness or internal restlessness in the morning. A final scientific assessment is pending, however.

If you forget to take L-thyroxine, you do not have to take it. Then just swallow - according to your treatment plan - the next regular dose at the scheduled time.

Discontinue L-thryroxine

Patients with an underactive thyroid or goiter usually have to take L-thyroxine for life. Because if you stop taking L-thyroxine or tapering it off (slowly reducing the dose), the symptoms of the underlying thyroid disease will return over time.

This also applies to thyroid inflammation: stopping L-thyroxine is usually not an option in Hashimoto's thyroiditis. Because the autoimmune disease destroys thyroid tissue in stages and irretrievably. The rest of the tissue can only produce L-thyroxine to a limited extent, so the hormone must be supplied permanently.

Stopping L-thyroxine can be dangerous. Therefore, you should never stop treatment with L-thyroxine yourself or reduce your dose, but always talk to your doctor first!

What side effects does L-thyroxine have?

Once the dosage has been set correctly, L-thyroxine is usually well tolerated. Nevertheless, as with any drug, side effects can occur with L-thyroxine, especially in the initial phase of therapy. Possible side effects include, for example:

• Palpitations / racing heart
• insomnia
• headache
• Nervousness, inner restlessness
• increased intracranial pressure (mainly in children)
• Cardiac arrhythmias
• increased sweating
• skin rash
• Muscle weakness
• Gastrointestinal complaints
• Tremble
• Menstrual cramps
• Weight loss

Another side effect of L-thyroxine affects women going through menopause: L-thyroxine increases their risk of osteoporosis. L-thyroxine can also cause water retention. However, this happens relatively rarely.

L-thyroxine: overdose

If too high a dose of L-thyroxine is used, there is a risk of side effects. The typical symptoms of an overactive thyroid such as racing heart, high blood pressure, diarrhea, vomiting and / or abdominal pain, anxiety and restlessness, profuse sweating or fever usually appear.

In the event of an acute, significant overdose of L-thyroxine, you should observe the following recommendations:

• do not force vomiting
• do not drink water
• Contact the poison control center, outpatient clinic or attending physician

L-thyroxine: underdose

The correct dosage depends, among other things, on the type and severity of the thyroid disease to be treated, the absorption capacity of the intestine and possible interactions with other substances. Against this background, an underdose can occur, especially at the beginning of L-thyroxine therapy, as the doctor approaches the right dose step by step.

If the L-thyroxine is underdosed, the symptoms of thyroxine deficiency such as tiredness and fatigue remain at least in a weakened form.

If you notice that your symptoms do not (completely) disappear despite taking L-thyroxine, you should inform your doctor about this. He will then increase the dose if necessary.

When should I not take L-thyroxine?

Patients who are allergic to the active ingredient should not use L-thyroxine. Other contraindications are:

• untreated hyperthyroidism or adrenal weakness
• acute myocardial infarction, acute inflammation of the myocardium, acute inflammation of the wall of the heart (pancarditis)
• untreated pituitary gland dysfunction

Pregnant women can and must continue to take the prescribed L-thyroxine. However, the dose may need to be adjusted as the need for hormones may increase during pregnancy. It is not allowed to take L-thyroxine and thyroid blockers at the same time during pregnancy.

L-thyroxine: interactions

Certain drugs can affect the way L-thyroxine works, including:

• Phenytoin (medicine for epilepsy, cardiac arrhythmias and nerve pain)
• Salicylates (pain relievers and fever killers)
• Dicumarol (anticoagulant)
• Furosemide (dehydrating agent = diuretic)
• Sertraline (antidepressant)
• Chloroquine and proguanil (anti-malarial agents)
• Barbiturates (sleeping pills and sedatives)
• Amiodarone (used to treat irregular heartbeat)

In addition, the pill can increase the need for L-thyroxine.

Certain foods and dietary supplements also influence the effect by delaying the absorption of L-thyroxine through the intestines. This applies above all to milk, foods containing soy, high-fat foods, calcium and iron supplements and antacids (acid binders, for example for heartburn).

Conversely, L-thyroxine can also slow down the effects of other drugs. The artificial hormone can, for example:

• decrease the blood sugar lowering effects of metformin, insulin or glibenclamide
• increase the anticoagulant effects of certain drugs such as phenprocoumon

By the way: some people worry about a possible interaction between L-thyroxine and vitamin D - presumably because an underactive thyroid is often associated with a vitamin D deficiency. Then it may be indicated to take vitamin D supplements in addition to L-thyroxine. This is usually not a problem because the two active ingredients don't seem to affect each other.

In general, the following applies: Discuss the simultaneous use of L-thyroxine and other drugs or food supplements with a doctor or pharmacist first.

Where can you get medicines containing L-thyroxine?

L-thyroxine supplements require a prescription. On presentation of a doctor's prescription, you can get the medication at the pharmacy.

How long has L-thyroxine been known?

On Christmas Eve 1914, the researcher Edward C. Kendall succeeded for the first time in isolating the long-sought thyroid hormones. This laid the foundation for the artificial production of thyroxine - in the form of L-thyroxine.

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