Mentzer index
Mentzer Index is a hematological tool used to help differentiate between iron deficiency anemia (IDA) and thalassemia trait (TT) when a patient presents with microcytic hypochromic anemia.
๐ Formula
Mentzer Index=MCV (fL)RBC count (millions/ยตL)\text{Mentzer Index} = \frac{\text{MCV (fL)}}{\text{RBC count (millions/ยตL)}}Mentzer Index=RBC count (millions/ยตL)MCV (fL)โ
๐ Interpretation
| Mentzer Index | Suggests | Explanation |
|---|---|---|
| > 13 | Iron Deficiency Anemia (IDA) | Low MCV with reduced RBC count โ ratio rises |
| < 13 | Thalassemia Trait (TT) | Low MCV with relatively preserved/high RBC count โ ratio falls |
| โ 13 | Indeterminate | May need further evaluation |
๐งช Example
- Patient MCV = 70 fL, RBC count = 5.5 million/ยตL
Mentzer Index=705.5โ12.7\text{Mentzer Index} = \frac{70}{5.5} \approx 12.7Mentzer Index=5.570โโ12.7
โก Suggests Thalassemia trait.
โ๏ธ Limitations
- Only a screening tool, not diagnostic.
- Accuracy reduced if both IDA and thalassemia coexist.
- Other indices (Srivastava, Shine & Lal, Green & King, etc.) may also aid differentiation.
- Confirmatory tests: Iron studies, Hb electrophoresis, genetic testing.
๐ Do you want me to make MCQs on Mentzer Index (with WordPress-compatible quiz code like before), or a summary table comparing all RBC indices (Mentzer, Srivastava, Shine & Lal, etc.)?
MCV divided by the RBC count.
Helpful in differentiating iron deficiency anemia from beta thalassemia

Mentzer index
Quotient of the mean corpuscular volume (MCV, in fL) divided by the red blood cell count (RBC, in Millions per microLiter)
Mentzer index
Less than 13 Suggests thalassemia more likely
Greater than 13 Suggests iron-deficiency anemia more likely
Principle of Mentzer index
Iron deficiency
Marrow cannot produce as many RBCs
Small (microcytic),
RBC count and the MCV will both be low, and as a result, the index will be greater than 13.
Iron deficiency
Thalassemia
Disorder of globin synthesis
Number of RBCs produced is normal
Cells are smaller and more fragile.
RBC count is normal, but the MCV is low,
so the index will be less than 13
Thalassemia
| Index | Formula | Cut-off | IDA | Thalassemia Trait |
|---|---|---|---|---|
| Mentzer Index | MCV รท RBC | >13 โ IDA <13 โ TT |
>13 | <13 |
| Srivastava Index | MCH รท RBC | >3.8 โ IDA <3.8 โ TT |
>3.8 | <3.8 |
| Shine & Lal Index | MCVยฒ ร MCH ร 0.01 | >1530 โ IDA <1530 โ TT |
>1530 | <1530 |
| Green & King Index | (MCVยฒ ร RDW) รท (Hb ร 100) | >65 โ IDA <65 โ TT |
>65 | <65 |
| England & Fraser Index | MCV โ RBC โ (5 ร Hb) โ 3.4 | >0 โ IDA <0 โ TT |
>0 | <0 |


