was macht l thyroxin im körper — when to see a doctor?

L-thyroxine (levothyroxine) is a synthetic form of the thyroid hormone thyroxine (T4). In the body, it is converted to triiodothyronine (T3), the active hormone that regulates basal metabolic rate, heart rate, digestion, and numerous metabolic processes. It is prescribed for hypothyroidism (underactive thyroid) or after thyroid removal to restore normal hormone levels. You should see a doctor if you experience new symptoms such as fatigue, weight gain, cold intolerance, constipation, or low mood (possible underdose); or if you have palpitations, insomnia, tremors, or weight loss (possible overdose). Dose adjustments are also needed after pregnancy, significant weight changes, or when starting new medications. Regular blood tests (TSH, free T4) are essential. MyBody-X does not offer thyroid diagnostics; its tests are for wellness screening, not medical decisions. If you suspect a thyroid disorder, consult an endocrinologist or primary care physician.