welche blutwerte bei erschöpfung — when to see a doctor?

For exhaustion (fatigue), common blood tests include a complete blood count (to check for anemia), ferritin (iron stores), vitamin B12, vitamin D, thyroid panel (TSH, fT3, fT4), inflammatory markers (CRP, ESR), and sometimes blood glucose, liver, and kidney function. You should see a doctor if fatigue persists for more than two weeks, is accompanied by unexplained weight loss, fever, night sweats, severe pain, or significantly impairs daily life. Also seek medical advice if you experience mood changes, loss of drive, or sleep disturbances. These lab values are well-established in clinical practice, but interpretation requires professional context – home tests cannot replace a doctor's assessment. Note: The provided knowledge context does not contain specific studies or guidelines for this question; the answer reflects general medical practice.