Myths vs facts: Ferritin and Müdigkeit

Myths vs facts: Ferritin and fatigue. Ferritin is an iron-storage protein; low ferritin indicates iron deficiency, which can cause fatigue. Fact: Ferritin below 30 ng/mL is considered iron deficiency and is associated with fatigue (evidence: human-strong). Myth: A normal ferritin level rules out iron deficiency as a cause of fatigue. In reality, functional iron deficiency (e.g., due to inflammation) can occur where ferritin is falsely elevated by acute-phase response. Other common causes of fatigue include sleep deprivation, thyroid disorders, and depression. Another myth: High ferritin always means iron overload. Ferritin can rise due to inflammation, liver disease, or metabolic syndrome without iron overload. Measuring transferrin saturation and CRP helps differentiate. Caveat: Ferritin alone is insufficient for diagnosis; medical evaluation is needed. Supplementation without indication can be harmful (iron overload).