Objective To evaluate the value of mean reticulated hemoglobin content (Mchr) in diagnosing iron deficiency anemia (IDA) and assessing its severity. Methods This study included 302 patients with IDA from January 2021 to December 2021, recruited from Ruijin Hospital, Shanghai Jiao Tong University School of Medicine (North), Xinhua Hospital, and Ruijin Hospital. The cohort comprised 118 patients with mild anemia, 159 with moderate anemia, and 25 with severe anemia. In addition, 365 non-IDA patients (encompassing those with thalassemia, megaloblastic anemia, pure red cell aplastic anemia, hemolytic anemia, and aplastic anemia) and 138 healthy controls were included. Venous blood samples were collected from all participants for analysis of hemoglobin (Hb), hematocrit (HCT), Mchr, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), serum iron (Fe), transferrin saturation (TS), ferritin, and total iron-binding capacity (TIBC). Mchr levels were compared between the IDA and non-IDA patient groups and between different degrees of IDA severity. Receiver operating characteristic (ROC) curves were plotted to evaluate the diagnostic value of Mchr in IDA. Results Compared with the non-IDA group, the IDA cohort exhibited significantly reduced levels of Mchr, Hb, MCV, MCH, MCHC, HCT, Fe, TS, and ferritin, while TIBC was markedly elevated, with all differences being statistically significant (P<0.05). Mchr demonstrated positive correlations with Hb, MCV, MCH, MCHC, HCT, Fe, TS, and Ferritin, and a negative correlation with TIBC in the IDA group. Mchr levels decreased sequentially with increasing severity of IDA, with significant differences observed among the three groups (P<0.05). The ROC curve analysis revealed that the cut-off value of Mchr for diagnosing IDA was <26.7 pg, with a sensitivity of 80.00% and specificity of 93.38%, yielding an area under the curve (AUC) of 0.9338(95%CI: 0.9157-0.9518). The sensitivity and the specificity of Mchr+Fe+Ferrit+TIBC in diagnosing IDA (Fe<5.7 μmol/L, Ferritin<7.1 ng/mL, TIBC>65.8 μmol/L) were 90.76% and 94.70% respectively, and the AUC was 0.9839(95%CI: 0.9772-0.9905). Conclusions Mchr can serve as a potential clinical marker for screening IDA and its severity. Its combination with iron metabolism indicators adds diagnostic value for IDA, providing a strong basis for whether further invasive diagnosis is needed.