Measures of red blood cell size and hemoglobin content
20 of 22 providers
Complete Blood Count (CBC)
MCV:80-100 fL, MCH:27-33 pg, MCHC:32-36 g/dL
MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Hemoglobin), and MCHC (Mean Corpuscular Hemoglobin Concentration) are red blood cell indices that describe the size and hemoglobin content of your RBCs. MCV measures average RBC volume (80-100 femtoliters or fL), MCH measures average hemoglobin per RBC (27-33 picograms), and MCHC measures hemoglobin concentration within RBCs (32-36 g/dL).
These indices are critical for classifying anemia types:Microcytic (low MCV <80 fL) suggests iron deficiency or thalassemia. Macrocytic (high MCV >100 fL) suggests B12/folate deficiency or alcohol use. Normocytic (normal MCV) suggests anemia of chronic disease or blood loss. MCH generally mirrors MCV, while MCHC is most useful for detecting hereditary spherocytosis (elevated MCHC) or iron deficiency (low MCHC).
MCV is the most clinically useful index, guiding targeted testing:low MCV → check iron studies and hemoglobin electrophoresis (thalassemia). High MCV → check B12, folate, thyroid function, liver function. Normal MCV with anemia → check reticulocyte count, kidney function, inflammatory markers. The Mentzer index (MCV/RBC) helps distinguish iron deficiency (>13) from thalassemia trait (<13) when MCV is low.
| Range Type | Level | Significance |
|---|---|---|
| Optimal | MCV:85-95 fL, MCH:28-32 pg, MCHC:33-35 g/dL | Ideal RBC size and hemoglobin content. Indicates adequate iron, B12, and folate stores with efficient hemoglobin packaging. These values support optimal oxygen delivery and cellular function. |
| Borderline | MCV:78-85 or 95-102 fL | Low-normal MCV suggests early iron deficiency or thalassemia trait. High-normal may indicate early B12/folate deficiency, hypothyroidism, or alcohol use. Check ferritin, B12, folate, thyroid function. Retest in 3 months. |
| Microcytic (Small RBCs) | MCV <80 fL | Small RBCs indicate iron deficiency (most common), thalassemia, anemia of chronic disease, lead poisoning, or sideroblastic anemia. Check iron studies (ferritin, TIBC, iron saturation). If iron normal, consider hemoglobin electrophoresis for thalassemia. Mentzer index (MCV/RBC):>13 suggests iron deficiency, <13 suggests thalassemia. |
| Macrocytic (Large RBCs) | MCV >100 fL | Large RBCs indicate B12 deficiency, folate deficiency, hypothyroidism, liver disease, alcohol use, or medications (methotrexate, hydroxyurea, antiretrovirals). MCV >110 suggests megaloblastic anemia (B12/folate deficiency). Check B12, folate, TSH, liver enzymes, alcohol history. If B12/folate normal, consider bone marrow evaluation. |
Iron deficiency:Ferrous sulfate 325 mg 2-3x daily. MCV normalizes in 2-4 months as new RBCs with adequate iron are produced
Thalassemia trait:No treatment needed. Genetic counseling if planning pregnancy. Avoid iron supplementation unless truly deficient
Anemia of chronic disease:Treat underlying condition. Iron supplementation often ineffective due to hepcidin block
Lead poisoning:Chelation therapy if blood lead >45 mcg/dL. Remove exposure source
B12 deficiency:B12 1000 mcg IM weekly x 4-8 weeks, then monthly. MCV normalizes in 2-4 months
Folate deficiency:Folic acid 1-5 mg daily. MCV normalizes in 6-8 weeks. Always check B12 first—folate can mask B12 deficiency
Hypothyroidism:Levothyroxine replacement. MCV normalizes with thyroid correction
Alcohol-related:Abstinence. MCV decreases 1-2 fL per month after stopping alcohol. May take 2-4 months to normalize
Medication-induced:If from methotrexate, add leucovorin rescue. If from antivirals, may need dose reduction
When MCV <80 fL (microcytic), calculate Mentzer Index=MCV / RBC count:
>13:Suggests iron deficiency. Check ferritin, iron studies
<13:Suggests thalassemia trait. Order hemoglobin electrophoresis
This simple calculation has 90% accuracy in distinguishing these two common causes of microcytosis
Caution:Doesn't work if both conditions coexist or if severe anemia present
If anemia with normal MCV (80-100 fL), check:
Reticulocyte count:High suggests hemolysis or bleeding (bone marrow responding appropriately). Low suggests bone marrow suppression or chronic disease
Kidney function:Chronic kidney disease causes normocytic anemia from reduced EPO
Inflammatory markers:CRP, ESR elevated in anemia of chronic disease
Bone marrow:If cause unclear, may need bone marrow biopsy to evaluate production
MCV changes slowly:Takes 3-4 months for significant change (120-day RBC lifespan). Don't expect rapid MCV normalization
Early iron deficiency:Ferritin drops first, then MCV falls. MCV can be normal early in iron deficiency
Mixed deficiencies:Iron + B12 deficiency can give normal MCV (microcytic + macrocytic=normocytic). Check both if anemia present
Alcohol marker:MCV useful for monitoring abstinence. Decreases with sobriety, suggesting compliance
Medication monitoring:Check MCV every 3-6 months on hydroxyurea, methotrexate, or other medications affecting folate metabolism
MCV is the primary method for classifying anemias. Microcytic anemia (MCV <80) is 95% due to iron deficiency or thalassemia. Macrocytic anemia (MCV >100) is 80% due to B12/folate deficiency, alcohol, or liver disease. This classification narrows differential diagnosis and guides targeted testing, dramatically improving diagnostic efficiency.
Source:Hoffbrand AV, et al. Essential Haematology. 7th edition. Wiley-Blackwell. 2016.
The Mentzer Index (MCV/RBC) distinguishes iron deficiency from thalassemia trait with 90% accuracy when MCV <80. Index >13 suggests iron deficiency (low RBC count, low MCV). Index <13 suggests thalassemia trait (near-normal RBC count despite low MCV). This simple calculation prevents unnecessary iron therapy in thalassemia carriers.
Source:Mentzer WC Jr. Differentiation of iron deficiency from thalassaemia trait. Lancet. 1973;1(7808):882.
In B12 deficiency, MCV >110 fL has 95% specificity for megaloblastic anemia. However, 30% of B12-deficient patients have MCV <100 (normocytic) due to concurrent iron deficiency or thalassemia trait masking macrocytosis. Always check B12 if unexplained anemia, regardless of MCV.
Source:Carmel R. How I treat cobalamin (vitamin B12) deficiency. Blood. 2008;112(6):2214-2221.
Chronic alcohol consumption elevates MCV by 3-10 fL, often in the 100-110 range. This occurs even with normal B12 and folate due to direct marrow toxicity. MCV returns to normal 2-4 months after abstinence, making it useful for monitoring sobriety. However, MCV alone is insufficiently sensitive to screen for alcohol use disorder.
Source:Savage D, et al. Sensitivity of serum methylmalonic acid and total homocysteine determinations for diagnosing cobalamin and folate deficiencies. Am J Med. 1994;96(3):239-246.
Iron deficiency initially affects MCV before causing anemia. Falling MCV with normal hemoglobin indicates early iron depletion. This "iron deficiency without anemia"affects 15-20% of menstruating women and benefits from iron supplementation to improve fatigue and cognitive function, even without overt anemia.
Source:Camaschella C. Iron deficiency. Blood. 2019;133(1):30-39.
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $349 | 100+ | |
 InsideTracker | ✓ | $680 | 54 |
 Function Health | ✓ | $365 | 100+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| — | $399 | 100+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| — | $125 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 129 |
20 providers include this biomarker in their panels
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
