GLOSSARY

Ferritin is a cellular iron-storage protein; its blood measurement is a context-dependent marker influenced by inflammation.

Serum iron varies and alone does not diagnose stores; ferritin, hemoglobin and transferrin saturation provide complementary information with clinical context. Ferritin rises with inflammation, so a high value is not always overload. Record sampling time, recent illness and hard training. Diagnostic criteria and treatment targets differ by setting; there is no single ideal value for every athlete regardless of symptoms and methods.

Absorbed iron exits intestinal cells through ferroportin and circulates bound to transferrin; ferritin supports cellular storage. Hepcidin limits export from intestinal cells and some stores by acting on ferroportin, changing with inflammation and iron status. Strenuous activity can transiently influence this regulation. More intake therefore does not always produce a proportional rise in uptake or iron available for physiological use.

Stores can decline before overt anemia, and iron deficiency without anemia differs from iron-deficiency anemia. Iron-restricted red-cell production is a functional problem; not every anemia is caused by iron. In athletes, investigate heavy menstrual bleeding, gastrointestinal bleeding, low intake and malabsorption. Treatment addresses the underlying cause as well as laboratory improvement, rather than treating the test number as the entire problem.