Color index is the ratio between the percentage of haemoglobin and the percentage of red blood cells in the blood. Actually it is the average haemoglobin content in one cell of a patient compared to the average haemoglobin content in one cell of a normal person.
Normal colour index is 1.0. It is useful in determining the type of anaemia.
Increases due to macrocytic anaemia and megaloblastic anaemia. Decreases due to iron deficiency anaemia. Normal in normocytic normochromic anaemia.
Colour index is calculated by dividing the hemoglobin percentage by the RBC count percentage