_1773586406 20260315145326000 Editor editor.jddt@gmail.com Universal Journal of Pharmaceutical Research Universal Journal of Pharmaceutical Research Univ J Pharm Res 2456-8058 2831-5235 03 15 2026 Emmanuel Ifeanyi Obeagu Salma Abdi Mahmoud Anemia continues to be one of the most common and overlooked complications in early breast cancer, caused by inflammation related to tumors, iron storage, and treatment-induced suppression of the bone marrow. Determining the root cause of anemia is essential for enhancing treatment and improving patient results. This review examines the potential diagnostic significance of the Mentzer index a ratio of mean corpuscular volume to red blood cell count as a straightforward, affordable method for distinguishing anemia patterns in early breast cancer. Historically utilized to differentiate iron deficiency anemia from thalassemia trait, recent findings indicate that MI might also represent the erythropoietic and inflammatory changes linked to malignancy. A narrative review method was utilized, consolidating existing literature (2015–2024) regarding the mechanisms of anemia in breast cancer, red blood cell indices, and biomarkers for iron metabolism. Research from PubMed, Scopus, and Google Scholar was evaluated to investigate the diagnostic and pathophysiological connections between the Mentzer index and anemia associated with cancer. Results show that increased MI values in early breast cancer frequently relate to functional iron deficiency due to hepcidin-induced iron blockage and inflammation-related suppression of erythropoiesis. On the other hand, low or normal MI levels might indicate mixed or nutritional anemia conditions. Incorporating MI with biomarkers like ferritin, transferrin saturation, and red cell distribution width improves diagnostic accuracy, especially in resource-constrained environments. The Mentzer index, while rooted in tradition, could offer a significant hematologic insight into anemia types in early breast cancer, enabling personalized interventions and enhanced treatment preparedness.                   Peer Review History: Received 4 December 2025;   Reviewed 11 January 2026; Accepted  13 February; Available online 15 March 2026 Academic Editor: Dr. Tamer Elhabibi, Suez Canal University, Egypt, tamer_hassan@pharm.suez.edu.eg Reviewers: Dr. Taiwo O Elufioye, University of Ibadan, Nigeria, toonitaiwo@yahoo.com Dr. Tanveer Ahmed Khan, Hajvery University, Lahore, Pakistan, tanveerahmedkhan754@gmail.com 03 15 2026 http://creativecommons.org/licenses/by-nc/4.0 10.22270/ujpr.v11i1.1492 https://ujpronline.com/index.php/journal/article/view/1492 https://ujpronline.com/index.php/journal/article/download/1492/2094 https://ujpronline.com/index.php/journal/article/download/1492/2094 https://ujpronline.com/index.php/journal/article/download/1492/2095 https://ujpronline.com/index.php/journal/article/download/1492/2112