NUTRITION: Edited by Eamonn M.M. QuigleyIron deficiency: a modern primer to diagnosis and managementAlexandre, Leoa,b; Chan, Simon S.M.a,bAuthor Information aDepartment of Gastroenterology, Norfolk and Norwich University Hospital NHS Trust bDepartment of Medicine, Norwich Medical School, University of East Anglia, Norwich, UK Correspondence to Simon S.M. Chan, Department of Medicine, Norwich Medical School, University of East Anglia, Norwich, UK. E-mail: [email protected] Current Opinion in Gastroenterology: March 2021 - Volume 37 - Issue 2 - p 121-127 doi: 10.1097/MOG.0000000000000702 Buy Metrics Abstract Purpose of review Iron deficiency with anemia (IDA) and without anemia remain a diagnostic and management challenge. Iron deficiency has a broad spectrum of causes, including gastrointestinal malignancy. The purpose of this review is to summarize the value and limitations of current methods to diagnose iron deficiency and underline the relevance of contemporaneous evidence to guide the pretest probability of gastrointestinal disease. Recent findings A number of biomarkers for iron deficiency exist, and all have their caveats. Serum ferritin remains the most pragmatic means of diagnosing iron deficiency. Hepcidin holds future promise as a marker of iron status during inflammatory states. Men and postmenopausal women with IDA have the highest overall prevalence of gastrointestinal malignancy (∼11%), while premenopausal women with IDA (<1.5%) and those with iron deficiency without anemia (<0.5%) have a very low risk. Noninvasive investigation with fecal immunochemical test and fecal calprotectin hold promise to guide further investigations in lower risk groups. Summary Confirmation of iron deficiency remains a challenge. Appropriate risk stratification is the key to guiding judicious gastrointestinal investigation. Use of noninvasive tests may play an important role in lower risk groups. Risk prediction tools applicable to relevant populations are required. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.