Iron deficiency often begins with declining iron stores (ferritin) and may progress to iron-deficiency anemia when hemoglobin production is affected. Symptoms can include easy fatigue, exertional shortness of breath, palpitations, dizziness, poor concentration, and pallor. The underlying cause is as important as treatment—heavy menstrual bleeding, gastrointestinal blood loss, inadequate intake, malabsorption, and pregnancy should be considered. In men and post-menopausal women, iron deficiency may warrant careful evaluation for occult blood loss. Supplementation aims not only to raise hemoglobin but also to safely restore iron stores, while avoiding unnecessary prolonged use.\n\nSource note: NIH ODS iron fact sheet (deficiency, anemia, evaluation, safety).