Mean reticulocyte volume (MRV) as a diagnostic marker for erythropoiesis: results with Mindray BC-6800 Plus

Background: Comprehensive iron status and erythropoiesis evaluation requires a combination of reliable tests and clinical indicators. Current diagnostic tools for these evaluations have key limitations that justify the exploration of mean reticulocyte volume (MRV) alongside or in combination with other reticulocyte indices. Mindray BC-6800 Plus TM counter reports MRV. We study its values in anemia of different underlying causes, the reliability for the diagnosis of iron deficient erythropoiesis (IDE), and its trend in response to therapy. Methods: Precision was assessed by repeated analysis; stability was tested by re-measuring samples after 0, 8, and 24 hours of store. A prospective study was conducted during 4 months. The study group included 553 consecutive patients, 196 non-anemic (105 were considered healthy and 91 latent iron deficiency), the 357 anemic patients (135 microcytic, 145 normocytic and 77 macrocytic). A total of 189 patients at diagnosis of anemia were studied at a second follow-up visit, with MRV reassessed after oral or intravenous (IV) iron supplementation at the specified intervals, to verify the change in MRV after therapy. Differences among groups were assessed using analysis of variance, with significance at P<0.05. Receiver operating characteristic analysis was used to assess the diagnostic performance of MRV for detecting IDE, and the gold standard was soluble transferrin receptor (sTfR) >52 nmol/L. A validation group of 150 consecutive patients, collected in a separate period and with similar inclusion criteria, served to confirm findings. The recruitment period was November 2024–January 2025 (study group) and February 2025 (validation group) in Hospital Galdakao Usansolo. Results: Coefficients of variation (CVs) of MRV measurements were <1.0%, MRV was stable within 8 hours. By using a cut-off of 94.6 fL, IDE can be diagnosed with a sensitivity of 82.9% and a specificity of 97.6%. The area under the curve was 0.929 [95% confidence interval (CI): 0.889–0.949]. Four weeks after oral iron therapy MRV showed an average increase of 4.5%; when the selected therapy was IV iron the average increment was 8.2% within 1 week, P<0.001. Conclusions: MRV is a reliable marker to identify IDE, useful not only for a real-time evaluation of erythropoiesis also to verify the effectiveness of iron replacement. MRV may allow the early detection of iron deficiency, facilitating timely diagnosis and management of the disease.