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Blood Indices – Definition, Calculation Methods & Types

Presentation Notes of Mean Corpuscular Hemoglobin Volume Concentration & red Blood Cell Indices Calculation with interpretation in word/ .ppt/ .pdf Format

BLOOD INDICES
Blood indices are specifically meant for erythrocytes. The number, shape, volume and the colour of the red blood cells indicate the quality of blood. So, these features are named as blood indices.

IMPORTANCE OF BLOOD INDICES
Blood indices have got diagnostic value in determining the type of anemia.

DIFFERENT BLOOD INDICES
Following are the various blood indices:
1.   Mean Corpuscular Volume (MCV) .
2.   Mean Corpuscular Hemoglobin (MCH)
3.   Mean Corpuscular Hemoglobin Concentration (MCHC)
4.   Colour Index (Cl).

CALCULATION OF BLOOD INDICES
Blood indices are calculated by using different formula. These calculations require the values of RBC count, hemoglobin content and PCV. For example, the values from the blood of a male subject are:
RBC count                     = 4 millions/cu mm.
Hemoglobin content   = 8 g%
PCV                               = 30%
Colour index, MCV, MCH and MCHC are calculated as follows:

1. Mean Corpuscular Volume (MCV)
MCV is the average volume of a single red blood cells. it is expressed in cubic microns (cu.μ)The normal is 90 cu.μ(78 to 90 cu.μ. When MCV is increased, the cell is known as a macrocyte and when it is decreased, the cell is called microcyte. MCV is more in pernicious anemia and megaloblastic anemia in which the red blood cells are macrocytic in nature. MCV is less in microcytic anemia.

2. Mean Corpuscular Hemoglobin (MCH)
This is the quantity or amount of hemoglobin present in one red blood cell. It is expressed in micro micro gram or Pico gram (pg). The normal value of MCH is 30 pg (27 to 32 pg.). It decreases or remains normal in pernicious anemia and megaloblastic anemia, in which red blood cells are macrocytic and normochromic or hypochromic. It decreases in hypochromic anemia. When MCH is normal, it is called normochromic state.

 3. Mean Corpuscular Hemoglobin Concentration (MCHC)
This is the concentration of hemoglobin in one red blood cell. It is the amount of hemoglobin expressed in relation to the volume of one red blood cell. So, the unit of expression is percentage. This is the most important absolute value in the diagnosis of anemia. The normal value of MCHC is 30% (30 to 38%). It is decreased in iron deficiency anemia in which, red blood cells are microcytic and hypochromic.

4. Colour Index (Cl)
This is the ratio between the percentage of hemoglobin and the percentage of red blood cells in the blood. Actually, this is the average hemoglobin content in one cell of a patient compared to the average hemoglobin content in j one cell of a normal person. The normal colour index is 1.0 (0.8 to 1.2). This was widely used in olden days. However, it is useful in determining the type of anemia. It is raised in pernicious anemia and megaloblastic anemia. It is reduced in iron deficiency anemia. And, it is normal in normocytic normochromic anemia.

CALCULATION OF BLOOD INDICES
Blood indices are calculated by using different formula. These calculations require the values of RBC count, hemoglobin content and PCV. For example, the values from the blood of a male subject are:
RBC count                     = 4 millions/cu mm.
Hemoglobin content   = 8 g%
PCV                               = 30%
Colour index, MCV, MCH and MCHC are calculated as follows:

Colour Index
This is calculated by dividing the hemoglobin percentage by the red blood cell count percentage.                  
Thus, the Colour Index    =   Hemoglobin%    /   RBC %
 Hemoglobin % =      Hemoglobin content in the subject                                                                          
                                    Normal hemoglobin content  = 53.3%
RBC %       =   RBC count in the subject× 100
Normal RBC count :-          
                        (4 millions/cu mm) / 5 millions/cu mm   x 100 = 80%                        
By using these two, Cl is calculated                                                               
Colour Index     = Hemoglobin%  53.3% /  RBC%  80%
Colour Index    =        0.67  

Mean Corpuscular Volume
MCV   = Volume of packed cells in ml per 1,000 ml of blood / Red blood cells in millions per cu mm of blood
PCV in 1000 ml or in 100 ml x 10
RBC count in millions/cu mm
30 x 10 M.CV  / 4   = 75 cu μ

Mean Corpuscular Hemoglobin                     
MCH   = Hemoglobin in grams per 1000 ml of blood / RBC count in millions/cu mm
             = 80 pg / 4
Thus, MCH = 20 pg. or micro micro gram.

Mean Corpuscular Hemoglobin Concentration
 MCHC    =  Hemoglobin in grams/ 100 ml of blood  × 100
PCV in 100 ml of blood   =  800 / 30 %
Thus, MCHC = 26.67%.
Results                                    
Cl = 0.67                    (Normal = 0.8 to 1.2)
MCV = 75 cuμ            (Normal = 78 to 90 cu. n
MCH =20pg               (Normal = 27 to 32 pg.)
MCHC =26.67            (Normal = 30 to 38%)     

The results of these indices indicate that the persor is suffering from microcytic hypochromic anemia, commonly occurs during the deficiency of iron.

Download Presentation of Blood Indices

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