welche blutwerte sind wichtig bei müdigkeit — what does this mean exactly?

When evaluating fatigue, blood tests are a standard first step to identify common medical causes. Key parameters often include: iron and ferritin (to detect iron deficiency anemia), vitamin B12 and folate (for megaloblastic anemia), vitamin D (deficiency linked to fatigue), thyroid function (TSH, fT3, fT4), and a complete blood count (hemoglobin, red blood cells). Inflammatory markers like CRP may also be relevant. However, no single lab value is diagnostic on its own; results must be interpreted by a physician in the context of symptoms and history. Direct-to-consumer DNA tests (e.g., from MyBody-X) can indicate genetic predispositions for certain metabolic pathways (e.g., vitamin D receptor variants), but they do not measure actual blood levels and have limited predictive power. The evidence for such genetic tests is mixed or weak, as lifestyle and environment play a much larger role. Caveat: fatigue can stem from non-medical causes (poor sleep, stress, depression) that no blood test can capture. Always consult a doctor before taking supplements based on test results.