What to watch with Ferritin and Müdigkeit?

Ferritin is the key marker for iron stores. Low ferritin (e.g., <30 µg/L) can cause fatigue, brain fog, and reduced exercise capacity even without full anemia—this is called 'functional iron deficiency.' High ferritin may indicate inflammation, infection, liver disease, or iron overload (hemochromatosis). When evaluating fatigue, ferritin should be interpreted together with hemoglobin, transferrin saturation, and CRP to distinguish true iron deficiency from inflammation-driven elevation. A consumer test like MyBody-X can provide a useful snapshot but cannot diagnose the cause of fatigue. Caveats: ferritin is an acute-phase reactant; it can be falsely elevated during illness. Also, fatigue is multifactorial—thyroid, vitamin D, sleep, and stress are common contributors. Evidence for the ferritin-fatigue link is moderate (observational studies, limited RCTs). For persistent fatigue, consult a physician for a complete workup including iron panel, CBC, and inflammatory markers.