Introduction:Iron deficiency is the most common nutritional disorder in humans, accounting for more than half of the estimated 1.76 billion cases of anemia worldwide (https://www.healthdata.org/). Anemia is a serious health problem, but, even without anemia, people with iron deficiency may experience fatigue, headaches, restless legs, and other physical and cognitive impairments, severely limiting their daily activities and quality of life. Patients may require long-term iron replacement therapy to replenish iron stores. Traditional oral iron salts are often associated with intolerable gastrointestinal toxicity and poor absorption. Ferric maltol is a European Medicines Agency- and U.S. Food and Drug Administration-approved oral iron formulation that was uniquely designed to improve gastrointestinal absorption, resulting in increased iron uptake while minimizing the risk of intestinal damage or dysbiosis. In a Phase 1 study in adults with inflammatory bowel disease and iron deficiency, ferric maltol increased iron uptake and storage over time at twice-daily doses of 30-90 mg (Bokemeyer B et al. Eur J Drug Metab Pharmacokinet2017;42:229-238). We assessed iron measures following ferric maltol treatment in patients with iron deficiency with or without anemia.