en آسيب شناسي Pathology تحقيقي Original Paper <div style="text-align: justify;"><span style="font-size:12px;"><span style="font-family:Times New Roman;"><b>Background:</b> Anaemia is a common clinical condition with diverse etiologies and is traditionally classified using red cell indices such as mean corpuscular volume (MCV) and red cell distribution width (RDW). However, these parameters provide only static morphological information. Newer reticulocyte-derived indices-Mean Reticulocyte Volume (MRV), Immature Reticulocyte Fraction (IRF), and Red Cell Size Factor (RSF)-offer dynamic insights into erythropoietic activity and iron availability. This study aimed to evaluate the diagnostic and interpretive utility of these parameters across different anaemia types.<br> <b>Methods:</b> A prospective cross-sectional study was conducted in a tertiary care hospital over 24 months. A total of 357 adult patients with anaemia were classified morphologically as microcytic (n=162), normocytic (n=124), or macrocytic (n=71) based on MCV. Complete blood counts and reticulocyte indices were measured using the Beckman Coulter DxH 900 analyzer. Continuous variables were compared using the t-test or Mann-Whitney U test, categorical variables were compared using the chi-square test, and correlations were assessed using Spearman&rsquo;s coefficient. Diagnostic cut-offs were determined by receiver operating characteristic (ROC) analysis.<br> <b>Results:</b> Microcytic anaemia showed the lowest MRV (109.0 &plusmn; 17.6 fL) and RSF (92.6 &plusmn; 13.0), while macrocytic anaemia showed the highest MRV (125.9 &plusmn; 25.2 fL) and RSF (103.4 &plusmn; 28.8). IRF was comparable across groups (0.43-0.46) but reflected marrow activity in regenerative versus suppressed states. RSF emerged as the most discriminative index for differentiating iron deficiency anaemia from thalassemia trait (AUC = 0.89, p < 0.001). MRV refined morphological classification, and IRF indicated marrow responsiveness.<br> <b>Conclusion</b>: Reticulocyte parameters add functional depth to conventional red cell indices, bridging morphology with erythropoietic dynamics. RSF is the most robust discriminator of anaemia type, MRV enhances size-based classification, and IRF serves as a real-time marker of marrow regeneration. Incorporation of these indices into routine haematology reporting can improve diagnostic accuracy and therapeutic monitoring without additional cost.</span></span></div> Anaemia, Reticulocytes, Mean Reticulocyte Volume, Immature Reticulocyte Fraction, Red Cell Size Factor, Diagnostic Haematology 8 14 http://mlj.goums.ac.ir/browse.php?a_code=A-10-2154-1&slc_lang=en&sid=1 Anjali Kelkar kelkar.anjali.jaydeep@gmail.com 0000-0003-3431-1491 Yes Ruby Hall Clinic, 40 Sassoon Road, Pune 411001, Maharashtra, India Shamli Joshi dr.shamlijoshi@gmail.com 0009-0002-9689-5875 No Ruby Hall Clinic, 40 Sassoon Road, Pune 411001, Maharashtra, India Vaishali Patil drvaishali.patil@rubyhall.com 0009-0000-7467-0013 No Ruby Hall Clinic, 40 Sassoon Road, Pune 411001, Maharashtra, India Harshal Patil drharshal.patil@rubyhall.com 0000-0001-8010-1263 No Ruby Hall Clinic, 40 Sassoon Road, Pune 411001, Maharashtra, India