was ist ein normaler schilddrüsenwert — what are common causes?

The question 'what is a normal thyroid value' cannot be answered with a single number because thyroid function is assessed by multiple markers (TSH, fT3, fT4) with lab-specific reference ranges. Typically, TSH between 0.5 and 4.5 mIU/L is considered normal, though some guidelines suggest a narrower target (0.5–2.5). The provided context does not contain specific reference values or a comprehensive list of common causes. It only mentions Hashimoto's thyroiditis as one autoimmune cause. Common causes of abnormal thyroid values include: Hashimoto's (autoimmune hypothyroidism), Graves' disease (hyperthyroidism), iodine deficiency, thyroid nodules, medications (e.g., amiodarone, lithium), and thyroiditis. A single abnormal reading does not confirm disease – stress, time of day, and diet can affect results. The evidence for these statements is based on general medical practice, not on the given context. If values are abnormal, an endocrinologist should perform repeated measurements and ultrasound.