Calculate MCV, MCH, and MCHC from CBC values, classify anemia as microcytic/normocytic/macrocytic, compute Mentzer index for thalassemia screening, and assess reticulocyte production index.
Red blood cell indices — MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Hemoglobin), and MCHC (Mean Corpuscular Hemoglobin Concentration) — are calculated from the basic complete blood count (CBC) parameters and provide the standard framework for classifying anemia patterns. These indices turn raw CBC data into morphology categories that help narrow the differential before additional tests are reviewed.
This calculator computes all three RBC indices from hemoglobin, hematocrit, and RBC count, classifies the anemia morphologically (microcytic/normocytic/macrocytic and hypochromic/normochromic/hyperchromic), calculates the Mentzer index for differentiating iron deficiency from thalassemia trait in microcytic anemias, and computes the corrected reticulocyte count and Reticulocyte Production Index (RPI) to assess bone marrow response adequacy.
The morphological classification of anemia by MCV is the usual first sorting step: microcytic patterns (MCV <80 fL) raise iron deficiency, thalassemia, or chronic disease; normocytic patterns (80–100 fL) can appear with blood loss, chronic disease, or marrow disorders; and macrocytic patterns (MCV >100 fL) raise B12/folate deficiency, liver disease, hypothyroidism, or myelodysplastic syndromes. Reticulocyte assessment then helps separate underproduction from destruction or blood loss.
RBC indices are the quickest way to sort anemia into a useful first pass before ordering more specialized tests. This calculator keeps the CBC-derived indices, morphology, Mentzer index, and reticulocyte response together so microcytic, normocytic, and macrocytic patterns can be interpreted from the same panel.
MCV = (Hct% / RBC) × 10 fL. MCH = (Hb / RBC) × 10 pg. MCHC = (Hb / Hct) × 100 g/dL. Mentzer Index = MCV / RBC (<13 favors thalassemia, >13 favors iron deficiency). Corrected Retic = Retic% × (Hct/45). RPI = Corrected Retic / Maturation Factor.
Result: MCV 71.4 fL (microcytic), MCH 22.6 pg, MCHC 31.7 g/dL (hypochromic), Mentzer 17.0 → iron deficiency
Low MCV (71.4) indicates microcytic anemia. Low MCHC (31.7) confirms hypochromia. Mentzer index 17.0 (>13) favors iron deficiency over thalassemia. Low RPI would confirm inadequate marrow response consistent with iron deficiency.
MCV is the simplest classification step because it separates small-cell, normal-cell, and large-cell anemia patterns. That first split guides the rest of the workup toward iron deficiency, chronic disease, blood loss, marrow failure, or B12/folate deficiency.
The Mentzer index is a screening clue, not a diagnosis, but it helps distinguish iron deficiency from thalassemia trait in microcytic anemia. Reticulocyte response then answers a different question: whether the marrow is responding appropriately or underproducing.
No single RBC index is enough by itself. MCV, MCH, MCHC, RDW, and reticulocytes are most useful when interpreted as a pattern, especially when the CBC is mixed or the patient has more than one cause of anemia.
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This page calculates MCV, MCH, and MCHC directly from hemoglobin, hematocrit, and RBC count, then uses the standard morphology bands to describe microcytic, normocytic, or macrocytic patterns and hypochromic versus normochromic patterns. When reticulocytes are entered, it also calculates the corrected reticulocyte percentage and reticulocyte production index. When anemia is microcytic, it reports the Mentzer index as a screening clue for iron deficiency versus thalassemia trait.
The output is intended as CBC interpretation support, not as a stand-alone diagnosis. RBC indices are most useful when read with the full CBC, smear findings, iron studies, B12/folate data, and the clinical context.
MCV measures the average red blood cell volume in femtoliters (fL). Low MCV (<80 fL) means small cells (microcytic), normal (80-100) means normal-sized, and high (>100) means large cells (macrocytic). It is the primary index for classifying anemias.
The Mentzer index (MCV ÷ RBC count) helps distinguish iron deficiency from thalassemia trait in microcytic anemia. Values <13 suggest thalassemia trait (many small cells), while >13 suggests iron deficiency (fewer normal-sized or small cells). Sensitivity is ~80%.
MCHC >36 g/dL suggests hereditary spherocytosis (densely packed spherical RBCs), dehydrated cells, or laboratory artifact. True hyperchromia is uncommon and warrants peripheral smear review.
RPI corrects the reticulocyte count for both anemia severity and reticulocyte maturation time. An RPI ≥2 in an anemic patient indicates adequate marrow response (hemolysis or blood loss). RPI <2 indicates hypoproliferation (iron/B12 deficiency, marrow suppression).
Yes. Combined iron and B12/folate deficiency can produce a normal MCV because the opposing effects (microcytosis + macrocytosis) cancel out. RDW will be elevated (anisocytosis), and peripheral smear will show a dimorphic picture.
RDW measures RBC size variation (anisocytosis). Elevated RDW (>14.5%) with microcytic anemia strongly suggests iron deficiency over thalassemia trait (which typically has normal RDW). RDW is also elevated in mixed deficiencies and myelodysplastic syndromes.