1. Introduction To Medical Technology
- Lab 17 -
Red Blood Cell Indices

2. Introduction
Red blood cell indices are measurements that describe the size and oxygen-carrying protein (hemoglobin) content of red blood cells. The indices are used to help in the differential diagnosis of anemia.
The relationships between the hematocrit, the hemoglobin level, and the RBC are converted to red blood cell indices through mathematical formulas.
The indices include these measurements:
Mean corpuscular volume (MCV);
Mean corpuscular hemoglobin (MCH);
Mean corpuscular hemoglobin concentration (MCHC).

3. Purpose
Anemia includes a variety of conditions with the same outcome: a person's blood cannot carry as much oxygen as it should.
A healthy person has an adequate number of correctly sized red blood cells that contain enough hemoglobin to carry sufficient oxygen to all the body's tissues.
An anemic person has red blood cells that are either too small or too few in number. As a result, the heart and lungs must work harder to make up for the lack of oxygen delivered to the tissues by the blood. 
Anemia is caused by many different diseases or disorders. The first step in finding the cause is to determine what type of anemia the person has. Red blood cell indices help to classify the anemia's.

4. Mean Corpuscular Volume

5. These size categories are used to classify anemia.
Normocytic anemia have normal-sized cells and a normal MCV.
Microcytic anemia have small cells and a decreased MCV.
Macrocytic anemia have large cells and an increased MCV.
Microcytic cells are found in:
Patients with iron deficiency anemia.
Thalassemia.
Macrocytic cells are found in:
Patients with liver disease or hypothyroidism
When there is asynchrony in RBC maturation (termed Megaloblastic anemia's).
Folate and vitamin B12 deficiencies.

6. Mean Corpuscular Hemoglobin (MCH)

7. Mean Corpuscular Hemoglobin Concentration (MCHC)

8. Values of normochromic cells range from 32 to 37g/dL.
Hypochromic cells are less than 32g/dL, and those of hyperchromic cells are greater than 37g/dL.
Hypochromic erythrocytes occur in thalassemia and iron deficiency.
Because there is a physical limit to the amount of hemoglobin that can fit in a cell, there is no hyperchromic category, a cell does not really contain more than 37g/dL of Hb, but its shape may have become spherocytic, making the cell appear full.
An MCHC > 37g/dL should be scrutinized carefully for an error in Hb value.

9. Summary of red cell indices in common anemia's
Type of Anemia
MCV
MCH
MCHC
Normocytic Normochromic N
Microcytic Hypochromic D
Macrocytic Normochromic I
N= Normal D= Decreased I= Increased

10. Key Terms Anemia Hypochromic Macrocytic
A variety of conditions in which a person's blood can't carry as much oxygen as it should due to a decreased number or size of red blood cells.
Hypochromic
A descriptive term applied to a red blood cell with a decreased concentration of hemoglobin.
Macrocytic
A descriptive term applied to a larger than normal red blood cell.
Mean corpuscular hemoglobin (MCH)
A measurement of the average weight of hemoglobin in a red blood cell.
Mean corpuscular hemoglobin concentration (MCHC)
The measurement of the average concentration of hemoglobin in a red blood cell.

11. Mean corpuscular volume (MCV) Microcytic
A measure of the average volume of a red blood cell.
Microcytic
A descriptive term applied to a smaller than normal red blood cell.
Normochromic
A descriptive term applied to a red blood cell with a normal concentration of hemoglobin.
Normocytic
A descriptive term applied to a red blood cell of normal size.
Red blood cell indices
Measurements that describe the size and hemoglobin content of red blood cells.