was kann man im blut alles feststellen — what does this mean exactly?

The question asks what can be detected in blood – and the answer is quite broad. A complete blood count reveals red and white blood cells, platelets, hemoglobin, and hematocrit. Metabolic panels measure blood glucose (fasting or HbA1c), lipids (cholesterol, triglycerides), liver and kidney function (GOT, GPT, creatinine, urea), electrolytes (sodium, potassium, calcium), vitamins (D, B12, folate), and trace elements (iron, zinc, selenium). Hormones (thyroid, sex hormones, cortisol) and inflammatory markers (CRP) are also assessable. Specialized tests detect infections (antibodies, pathogen DNA) or tumor markers. Modern genetic analyses from blood DNA – as offered by MyBody-X – examine gene variants affecting nutrient, caffeine, or alcohol metabolism. However, blood values are only snapshots and fluctuate. No blood test can diagnose diseases; that remains a physician's task. Direct-to-consumer tests often have small effect sizes and lack clinical validation. For abnormal results or symptoms, always consult a doctor.