Sehgal index calculator: below 972 vs above 972
Short answer: The Sehgal index has no normal range in the usual sense. It is a cut-off of 972, used when red cells are small (MCV below 80 fL): below 972 suggests thalassaemia trait, and a high result, 972 or above, suggests iron deficiency. Ferritin and haemoglobin electrophoresis confirm which it is.
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Sehgal index calculator
Sehgal index = MCV × MCV ÷ red cell count
Source: Sehgal K, Mansukhani P, Dadu T, Irani M, Khodaiji S. Sehgal index: a new index and its comparison with other complete blood count-based indices for screening of beta thalassemia trait. Indian J Pathol Microbiol 2015;58(3):310-315.
In fL, from your full blood count
In millions per µL, the same number as ×10¹²/L. For example 4.8
Your result
Enter the numbers from your lab report to see your result.
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A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.
Another red-cell index used in anaemia screening.
How to read it
Adult reference range.
- Thalassaemia trait likely< 972 index
- Iron deficiency likely≥ 972 index
What it measures
Another discriminant index for small red cells, squaring MCV and dividing by red cell count. It is read alongside Mentzer rather than instead of it.
What moves it
Another calculated screening index for small red cells, used the same way and with the same caveat.
What to do next
Useful in populations where thalassaemia trait is common, which includes much of the Mediterranean and the Gulf. Confirm properly before concluding anything.
How fast it responds
It follows the underlying cause.
Also reported as: sehgal
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Common questions
- What does a high Sehgal index mean?
- A high Sehgal index, 972 or above, suggests iron deficiency rather than thalassaemia trait, if your red cells are small (MCV below 80 fL). A ferritin test confirms it. If your MCV is normal, the index does not apply.
- What does a Sehgal index below 972 mean?
- When red cells are small, a result below 972 points towards thalassaemia trait. It is a screening pointer, not a diagnosis. Haemoglobin electrophoresis or an HbA2 test confirms it.
- How do you calculate the Sehgal index?
- Multiply the MCV (in fL) by itself and divide by the red blood cell count (in millions per µL). For example, an MCV of 66 fL with a red cell count of 5.5 gives 66 × 66 ÷ 5.5 = 792.
- Sehgal or Mentzer index: which should I use?
- Both use the same two numbers and usually agree, so read them together. When they disagree the answer is uncertain, and ferritin plus haemoglobin electrophoresis settle it.
More in Complete Blood Count
Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.