Red blood cell indices, MCV,MCH,MCHC,RDW and CI

1. RED BLOOD CELL
INDICES
Dr. JILSHA

2. CONTENTS
• Introduction
• Mean corpuscular volume
• Mean corpuscular haemoglobin
• Mean corpuscular haemoglobin
concentration.
• Red Cell Distribution width
• Colour Index

3. INTRODUCTION
• The values of Hemoglobin, Packed Cell
Volume (PCV) and Total RBC count are used to
calculate red cell volume and red cell
hemoglobin content and concentration. These
are called Red Blood Cell indices.

4. INTRODUCTION
• The commonly estimated indices are :
o Mean Cell Volume (MCV)
o Mean Cell Hemoglobin (MCH)
o Mean Cell Hemoglobin Concentration (MCHC)
oRed Cell Distribution Width (RDW)
• Determination of these indices are is of
considerable clinical importance and is
widely used in the classification of
anemia.

5. MEAN CORPUSCULAR VOLUME
(MCV)
• MCV is the average volume of an RBC
expressed in femtoliters (1 fL= 10-15 L).
• If the PCV and number of red cells per liter
are known, MCV is calculated as follows :
𝑀𝐶𝑉 𝑓𝐿 =
𝐻𝑒𝑚𝑎𝑡𝑜𝑐𝑟𝑖𝑡(%)×10
𝑅𝐵𝐶 𝑐𝑜𝑢𝑛𝑡 𝑖𝑛 𝑚𝑖𝑙𝑙𝑖𝑜𝑛𝑠/𝑐𝑢.𝑚𝑚

6. MCV
• The factor 10 is introduced to convert the
hematocrit reading in % from volume of
packed red cells per 100 mL to volume per
liter.
• For example if the hematocrit is 40% and the
red cell count is 5 million, then MCV is :
𝑀𝐶𝑉 =
40×10
5
= 80 fL

7. MCV
• Normal value : MCV in adults in between
78 fL to 96 fL.
APPLIED ASPECT
MCV is the index of the size of red cells. It depicts whether
the red cells are Microcytic, Normocytic or Macrocytic.
If the MCV is less than 78 FL, the cells are microcytic. If it is
greater than 96 FL, the cells are macrocytic.

8. MEAN CORPUSCULAR
HEMOGLOBIN (MCH)
• MCH is the average weight of hemoglobin
content in an RBC.
• It is expressed in picograms (1pg = 10 – 12 g)
• It is calculated as follows :
𝑀𝐶𝐻 =
𝐻𝑏(
𝑔
𝑑𝑙
) × 10
𝑅𝐵𝐶 𝑐𝑜𝑢𝑛𝑡 𝑖𝑛 𝑚𝑖𝑙𝑙𝑖𝑜𝑛𝑠 𝑝𝑒𝑟 𝑐𝑢. 𝑚𝑚

9. MCH
• For example, if the hemoglobin content is 14 g/dl
and the RBC count is 5 million:
𝑀𝐶𝐻 =
14×10
5
= 28 pg.
• Normal value : Normal range is 27 – 33 pg
APPLIED ASPECT
MCH will be as high as 50 pg in macrocytic anemia or as low
as 20 pg or less in microcytic hypochromic anemia

10. MEAN CORPUSCULAR HEMOGLOBIN
CONCENTRATION (MCHC)
• It is the average hemoglobin concentration
per unit volume of packed red cells.
• It is expressed as g/dl or percent.
𝑴𝑪𝑯𝑪 =
𝑯𝒃(
𝒈
𝟏𝟎𝟎𝒎𝒍
)
𝑷𝑪𝑽/𝟏𝟎𝟎𝒎𝒍
× 𝟏𝟎𝟎

11. MCHC
• For example, if the Hb concentration is 15 g/dl and
PCV is 45 %
𝑀𝐶𝐻𝐶 =
15
45
× 100 = 33.3 %
• Normal value : between 33-37 g/dl or %
APPLIED ASPECT
MCHC above 40% indicates error in instrument or manual
method as 37% is the limit for hemoglobin solubility .
In hypochromic anemias, the Hb concentration is reduced and
values as low as 20 – 25% are present.

12. RED CELL DISTRIBUTION WIDTH
(RDW)
• It is a measurement derived from the RBC
distribution curve generated on automated
hematology analyser and is an indicator of
variation in RBC size within a blood sample.
• It is used along with other indices to describe
the population of RBCs.

13. RDW
• It is calculated as follows :
𝑆𝐷 𝑜𝑓 𝑚𝑒𝑎𝑛 𝑐𝑒𝑙𝑙 𝑠𝑖𝑧𝑒
𝑀𝐶𝑉
× 100
• It is expressed in percentage.
• Normal range is 11-15%

14. COLOUR INDEX (CI)
• It refers to the ratio of Hb to RBC.
• For calculating CI, Hb of 14.8 g/dl is taken as
100% and RBC count of 5 million/mm3 is taken
as 100 %
𝐶𝐼 =
𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑜𝑓 𝑛𝑜𝑟𝑚𝑎𝑙 𝐻𝑏
𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑜𝑓 𝑛𝑜𝑟𝑚𝑎𝑙 𝑅𝐵𝐶 𝑐𝑜𝑢𝑛𝑡
• For eg., if Hb is 14.8 g/dl and RBC count is 4.5
million/mm3 then 4.5*100 = 90%, so,
CI = 100/90 = 1.11