What should I know about l thyroxin nebenwirkungen?

L-thyroxine (levothyroxine) is a thyroid hormone replacement for hypothyroidism. Side effects are usually dose-dependent: overdosing can cause palpitations, sweating, insomnia, weight loss, tremor, and anxiety; underdosing leads to fatigue, weight gain, constipation, and cold intolerance. Rare allergic reactions may occur. Dosage must be adjusted by a physician based on blood tests (TSH, fT3, fT4). Consumer DNA tests like MyBody-X are not validated for medication management. Genetic variants (e.g., in DIO1, DIO2) may influence thyroid hormone metabolism, but clinical utility is unclear. Do not use genetic test results to adjust your L-thyroxine dose. If you experience side effects, consult your doctor. This answer is based on general medical knowledge, not on the provided context.