Red blood cells

1. RED BLOOD CELLS
RBC COUNTING,VARIOUS INDICES
- Dr. Aman Kumar

2. RBC COUNT
• It is total number of RBC per μL or a liter of blood.
• The test can help to diagnose anemia with low number of RBCs
and other conditions affecting red blood cells.
• Conditions require RBC count are:
Kidney diseases
Anemia
Bonemarrow disorder like mylofibrosis

3. • Mature RBC is a biconcave disc about 7-8 μ in diameter.
• Normal volume is 80-100 fl, normal haemoglobin content is 28-34
pg/dl.
• Normal RBC count
Male: 4.3 – 5.9 (x 10 12/l or 106/μl)
Female: 3.5 – 5.0 (x10 12/l or 106/μl)

4. • Higher numbers of RBCs may be due to:
Cigarette smoking
Failure of the right side of the heart (cor pulmonale)
Dehydration (for example, from severe diarrhea)
Kidney tumor (renal cell carcinoma)
Low blood oxygen level (hypoxia)
Bone marrow disease that causes abnormal increase in RBCs (polycythemia vera)
Drugs like gentamycin / methyldopa

5. • Low number of RBC may be due to:
Anemia
Bleeding
Bone marrow failure (for example, from radiation, toxins, or tumor)
Deficiency of a hormone called erythropoietin (due to kidney disease)
RBC destruction (hemolysis) due to transfusion, blood vessel injury, or other
cause
Malnutrition
Multiple myeloma
Deficiency of iron, copper, folic acid, vit B6, or vit B12 in the diet
Pregnancy

6. HEMATOCRIT
• Hematocrit measures the volume that the RBC occupy within
whole blood.
• It is expressed in percentage or L/L.
• In automated analyzer, the hematocrit is usually calculated by the
measured MCV and RBC count by using formula
• Hematocrit = MCV (fl) x RBC count (x10 12/l) /1000

7. • One should interprets accuracy of RBC count, hematocrit and hemoglobin value
using quick formula
• called the “RULE OF THREE”.
• RBC Count x 3 = hemoglobin x 3 = hematocrit(%)
• If error > 3% of the measured value, a measurement error or instrument
malfunction suspected.
DIURNAL VARIATION
RBC Count, hematocrit and hemoglobin concentration shows diurnal variation
These values are higher in the morning

8. Red Blood Cell Indices
• Red blood cell indices : Are measurement that describe the size
and oxygen carrying protein (HB) content of red blood cells .
• The indices are used to help in the differential diagnosis of
anemia.
• They were first introduced by Wintrobe in 1929 to define the size
(MCV) and hemoglobin content (MCH & MCHC) of red blood cells.

9. DEFINITIONS:
Mean cell volume (MCV)
It is the measure of average volume of RBCs
Mean cell Hemoglobin (MCH)
It is a measurement of the average weight of hemoglobin in individual
erythrocytes.
Mean Cell Hemoglobin Concentration (MCHC)
It is the average concentration of hemoglobin in erythrocytes
Red cell distribution width (RDW)
It is a measure of variability of erythrocyte size

10. WHY RBC INDICES REQUIRED ?
• To classify the erythrocytes by their volume and Hemoglobin
content.
• This indices suggest how the RBC’s appear microscopically and
provide significant information (most commonly for Anemia
diagnosis)
• Laboratory professionals correlate the indices with Hct, Hb and
RBC count to ensure that technical problems are identified when
they occur.

11. MEAN CELL VOLUME
• MCV = Hct (L/L) x 1000 / RBC count ( x 10 12 /L)
• Normocytic: 80-100 fL
• Microcytic: Red cells with reduced volume
• Macrocytic: Red cells with an increased volume
• Remember MCV is a measurement of volume whereas estimation
of size of flattened cells is a measurement of cell diameter. Cell
diameter and cell volume are not same

12. MEAN CELL HEMOGLOBIN CONCENTRATION
• It is the average concentration of hemoglobin in a deciliter of
erythrocytes and expressed in g/dl
• It is the ratio of hemoglobin mass to volume in which it is
contained
• MCHC = Hb (g/dl) x 100 / Hct (L/L)
• Normochromic: 32-36g/dl
• Hypochromic: 32g/dl
• Hyperchromic: >36g/dl

13. MEAN CELL HEMOGLOBIN CONCENTRATION
• Hypochromic: If the area of central pallor is >1/3rd of the cell size
• Hyperchromic: The only erythrocyte that is hyperchromic with an
MCHC of > 36g/dl is the spherocyte
• Apparent hyperchromasia ( high MCHC) is usually due to an
artifactual increase in the haemoglobin result, due to haemolysis,
lipaemia, or large numbers of Heinz bodies

14. MEAN CELL HEMOGLOBIN
• It is a measurement of the average weight (in picograms 10 -12 g)
of hemoglobin in individual erythrocytes.
• It is calculated by:
• MCH = Hb (g/dl) x 10 / RBC( x 10 12/L)
• MCH varies in direct linear relationship with the MCV. Cells with
less volume contain less Hb and vice versa.
• Normal value for the MCH : 28 to 34 pg

15. MEAN CELL HEMOGLOBIN
MCH Increase
• B12 deficiency
• Folic acid deficiency
• Reticulocyte
• Hemolytic anemia
• alcoholism
MCH Decreases
• Iron deficiency anemia Thalassemia Anemia of chronic disorder

16. RED CELL DISTRIBUTION WIDTH
• RDW is used because MCV is less reliable in describing the
erythrocyte population when considerable variation in erythrocyte
size occurs.
• RDW is a coefficient of variation in size distribution of RBCs
• Measured as : RDW = Standard deviation of MCV × 100 / MCV
• Normal value:11.5-14.5%
• Increased value indicates ANISOCYTOSIS.

17. • RDW is increased in Iron deficiency anemia.
• While RDW is normal in Thalassaemia minor.
• Combination of low MCV and high RDW is one of the best screening
test for the Iron deficiency anemia.

18. RDW and MCV

19. RETCULOCYTES
• Premature RBC
• They contain remnants of Ribosomal RNA
• Number of reticulocytes in PBS is a fairly accurate reflaction of
erythropoietic activity
• It is most useful and cost effective test in monitoring and response
to iron therapy

20. RETCULOCYTES COUNT
• It can be done by two methods:
Manual method
Automated method
• Manual method-
Romanowsky stain can not stain reticulocytes effectively.
Suspect reticulocyte when Polychromatophilic cells on PBS with
Romanowsky stain seen (erythocyte with bluish tinge)
A supravital stain such as NEW METHYLENE BLUE, BRILLIANT
CRESYL BLUE must be used to identify reticulocytes.

21. LIMITATIONS OF RBC INDICES
• Though the test for RBC INDICES is cost effective and simple, it has its
own limitations. Such as,
It is a screening test not a diagnostic test
MCV is not reliable when Anisocytosis is present
In combine or dimorphic anemia again MCV is not reliable
MCV does not reflect the diameter of the RBC, It is a volume of RBC
False high or false low value, which should be evaluated further
Automated Reticulocyte count is not standardized yet. And manual
method has inter-observer bias.

22. SUMMARY
• RBC index (MCV, MCH, MCHC) and RBC count helps in diagnosis of
anemia
• Combination of various RBC indices (MCV, MCH, MCHC) especially
with RDW is useful in differential diagnosis of anemia
• Reticulocyte count is a important indicator of bone marrow
activity and it can also be useful in monitoring and response to
iron therapy

23. THANK YOU