was kann man im blut alles feststellen — when to see a doctor?

Blood tests can assess many health markers: complete blood count (RBC, WBC, platelets), lipids (cholesterol, triglycerides), liver and kidney function, blood glucose, electrolytes, vitamins, hormones (e.g., thyroid), and inflammatory markers (CRP). Direct-to-consumer tests (like MyBody-X) often provide only partial panels and are not diagnostic. You should see a doctor if you have persistent symptoms (fatigue, weight changes, pain), abnormal self-test results, or for routine preventive screening (e.g., health check-up from age 35). Crucially, no blood test replaces a clinical evaluation. Interpretation depends on age, sex, medications, and individual factors. Always have abnormal values medically clarified.