was tun bei eisenmangel — which blood markers matter?

The question about iron deficiency and relevant blood markers is not addressed in the provided context. The available information covers IgG food intolerance tests, DNA variants (BDNF, COMT, SLC6A4), and prolonged fasting – none of which relate to iron metabolism. Therefore, I can only offer general medical knowledge: key blood markers for iron deficiency include ferritin (iron stores), hemoglobin, transferrin saturation, serum iron, and possibly soluble transferrin receptor. Ferritin is the most sensitive marker, but as an acute-phase reactant it can be falsely elevated during inflammation – so concurrent CRP measurement is essential. Treatment depends on the underlying cause and severity: oral iron supplements (e.g., ferrous sulfate) are first-line; intravenous iron is used for intolerance or malabsorption. Self-diagnosis and treatment without medical supervision are risky because iron overload is harmful. The evidence for these statements is well-established in clinical practice, but the context provides no specific sources. If you experience symptoms such as fatigue, pallor, or poor concentration, consult a healthcare professional.