Why is my T4 value too low?

A T4 value that is too low indicates a thyroid hormone deficiency, which is usually caused by an underactive thyroid. The hypofunction can have various causes. Quite common in the population (especially in women) is the thyroid disease Hashimoto’s thyroiditis.

In this disease, the body produces special proteins (autoantibodies) that lead to inflammation and functional impairment of the thyroid tissue. Low T4 levels also occur when the thyroid gland has undergone surgery or irradiation with radioactive iodine as a result of the disease. In most cases, patients have to take thyroid hormones as tablets for the rest of their lives after such an operation. If the dosage is too low, an underfunctioning occurs and the T4 value is too low.

T4 as a drug

T4 is not only an important hormone produced by the body itself but also a very frequently prescribed drug. People with hypothyroidism (for example, as a result of thyroid surgery or thyroiditis) are dependent on taking T4 to lead a normal life. The tablet, which is usually taken once in the morning, replaces the function that is otherwise performed by the thyroid gland and covers the daily requirement of thyroid hormone.

An individual dose for each person’s individual needs must be determined. By regularly checking the blood values, the doctor can check this dose and adjust it if necessary. Drugs with the active ingredient T4 (tetraiodothyronine, often also called thyroxine) are available from various manufacturers in different dosages.

Depending on the manufacturer, the trade name varies. However, the active ingredient and effect are identical. Frequently prescribed preparations are for example L-thyroxine Henning or Euthyrox. The usual dosages range from 25 to 300μg (micrograms). There are also drugs that contain iodine in addition to T4, such as Thyronajodine or Iodine Hyrox.

T4 to remove

If you would like to lose weight, taking T4 is by no means an option. However, some people do cause weight loss by taking thyroid hormones. However, this is usually not successful and is also very dangerous.

Thyroid hormones (such as T4) increase the body’s energy metabolism, so people with hyperthyroidism often lose weight. However, if one takes thyroid hormones such as T4 without being dependent on them due to a thyroid disease, an artificially induced hyperthyroidism can occur. In addition to complaints such as restlessness, trembling, sweating or diarrhea, it can even lead to life-threatening consequences such as heart rhythm disorders. Anyone who would like to lose weight and also wants to maintain this weight in the long term can only achieve this by changing their eating habits (lower calorie intake) as well as through increased physical activity (higher calorie consumption).