welche blutwerte bei erschöpfung und müdigkeit — when to see a doctor?

The question about which blood values to check for exhaustion and fatigue is common, but the answer depends on the clinical context. The provided context does not contain specific blood value recommendations; it focuses on DNA tests (e.g., FTO, MC4R, VDR) and a few nutrient tests (vitamin D, ferritin). These are of limited use for fatigue workup. In standard medical practice, persistent fatigue typically warrants: complete blood count (anemia?), ferritin (iron deficiency), vitamin B12, folate, vitamin D, TSH (thyroid), inflammatory markers (CRP), and possibly liver/kidney function. You should see a doctor if fatigue lasts more than two weeks, is accompanied by unexplained weight loss, fever, night sweats, or other concerning symptoms. Important: Direct-to-consumer tests (like MyBody-X) are not a substitute for clinical diagnosis. The evidence for DNA-based fatigue analysis is weak (GWAS/mechanistic). The listed blood markers, however, are well-established (evidence: practice/guidelines).