was macht l thyroxin im körper — what does this mean exactly?

L-thyroxine (levothyroxine) is the synthetic form of the thyroid hormone thyroxine (T4). It is taken orally and converted in the body to triiodothyronine (T3), the active form that regulates metabolism. Its main functions: increase basal metabolic rate, promote growth and development, regulate heart rate, body temperature, and fat/carbohydrate metabolism. In hypothyroidism (underactive thyroid), L-thyroxine is used as replacement therapy to restore normal hormone levels. Dosage is individualized based on TSH levels. Excessive doses can cause hyperthyroidism symptoms such as palpitations, weight loss, and nervousness. Evidence for efficacy in overt hypothyroidism is strong (human-strong). For subclinical hypothyroidism or weight loss without medical indication, evidence is weaker. Important: L-thyroxine is not a dietary supplement and should only be taken under medical supervision. Interactions with calcium, iron, or fiber can impair absorption. Caveat: No self-medication; regular monitoring required.