Evidence check: TSH in the context of Müdigkeit

TSH is the standard screening marker for thyroid function and is often used as a first test in fatigue. The evidence is clinically established: hypothyroidism can cause fatigue, and TSH is the most sensitive indicator. However, fatigue is non-specific – many other causes (iron deficiency, vitamin D deficiency, sleep disorders, psychological stress) are possible. A normal TSH does not completely rule out thyroid dysfunction, especially if symptoms persist; then fT4 and fT3 may be useful. The evidence for TSH as a sole test in fatigue is strong for detecting primary hypothyroidism but weak for covering all fatigue causes. Home tests can provide a first hint but do not replace a clinical workup. Interpretation is limited by individual reference ranges and diurnal variation. Overall: TSH is a reasonable first step, not a comprehensive diagnosis.