welche blutwerte bei müdigkeit — when to see a doctor?

Fatigue is a common, non-specific symptom. Which blood tests are appropriate depends on accompanying symptoms, pre-existing conditions, and medications. In primary care, basic labs include: complete blood count (anemia?), ferritin (iron deficiency), vitamin B12, folate, vitamin D, TSH (thyroid), fasting glucose, and CRP (inflammation). If sleep apnea, depression, or chronic fatigue syndrome is suspected, further evaluation is needed. See a doctor if fatigue persists >2 weeks, or is accompanied by weight loss, fever, night sweats, or significant functional decline. Direct-to-consumer tests (e.g., from pharmacies) cannot replace medical diagnosis – they may yield false positives/negatives and cause unnecessary worry. Evidence for individual biomarkers varies: ferritin and B12 are well-supported, while so-called 'burnout markers' or 'fatigue panels' often rely on weak data. Always consult a physician before purchasing expensive self-tests.