Is Ferritin Eisenmangel useful for fatigue?

Ferritin is a storage protein for iron, and low ferritin indicates iron deficiency, a well-known cause of fatigue because iron is critical for oxygen transport and energy metabolism. Clinical evidence supports that iron supplementation in deficient individuals can improve fatigue. However, fatigue has many potential causes—sleep deprivation, stress, thyroid disorders, vitamin D deficiency, and others. A ferritin test alone is insufficient for diagnosis. Home test kits (e.g., from MyBody-X) may lack validated reference ranges and clinical interpretation. While a low ferritin result can be a useful clue, it should be confirmed and interpreted by a healthcare professional. Caution: normal ferritin does not rule out functional iron deficiency. Overall, ferritin testing is useful for fatigue when iron deficiency is suspected, but it is not a standalone screening tool. The evidence for the iron–fatigue link is strong, but the utility of a specific consumer test depends on its accuracy and context.