Red Blood Cell Indices Interpretations

What blood sample is needed for Red Blood cell Indices?

1. For Blood indices, the best sample is EDTA blood.
2. Collect the blood in the lavender top tubes.
3. Transport the blood to the lab and run in the hematology analyzer to calculate blood indices.
4. Blood is stable for 6 hours at 25 °C and for 24 hours at 4 °C.
5. Fetal blood is collected percutaneously from the umbilical area.

What are the indications for Red Blood cell Indices?

• These tests help diagnose various types of anemia.

What are the precautions for Red Blood Cell Indices?

1. The abnormal size of RBC may affect indices.
2. An increased count of WBC will affect the indices.
3. Increased reticulocyte count leads to abnormally high MCV.
4. Cold agglutinins give false increased values of MCH, MCHC, and MCV.

What is the definition of Red Blood cell Indices?

• Red cell indices define the size and contents of hemoglobin in Red blood cells.

Mean corpuscular volume (MCV):

How will you define MCV?

1. This is the average volume of red blood cells measured in cubic micrometers (µ³, femtoliter fL).
2. This indicates the cell size of RBCs.
3. This is the best index for classifying anemia.

What are the indications of MCV?

1. It helps in the classification and differential diagnosis of anemia.
2. It is a helpful screening test for occult alcoholism.

What are the factors interfering with MCV?

1. In the case of leucocytosis, there is increased MCV.
2. Marked hyperglycemia increases MCV.
3. Cold antibodies increase MCV.
4. Methanol poisoning increases MCV.
5. In the case of increased reticulocytes, there is increased MCV.
6. Hemolysis leads to a decrease in MCV.

How will you calculate MCV?

• MCV is calculated by dividing hematocrit by the total RBC count.

What is the normal MCV?

• Adult (all ages) = 80 to 95 fL
• Newborn = 96 to 108 fL

How are RBCs classified based on MCV?

1. Macrocytes are present when the MCV value is high, e.g., in megaloblastic anemia due to vitamin B and folic acid deficiency.
   1. In macrocytic anemia, MCV is 100 to 150 fL (>100 fL).
2. Microcytes, when the MCV is decreased, are seen in iron deficiency anemia and thalassemia.
   1. In microcytic anemia, MCV is 50 to 82 fL.
3. Normochromic normocytic anemia, MCV is 82 to 98 fL.
4. Normocytic anemia = MCV 80 to 94 fL  MCHC >30 g/dL.

What are the causes of increased MCV?

1. Pernicious anemia (vit B12 deficiency or folate deficiency).
2. Folic acid deficiency.
3. Antimetabolite treatment.
4. Chronic liver disease.
5. Alcoholism.
6. Sprue likes steatorrhea, celiac disease, and intestinal resection or fistula.
7. Fish tapeworm infestation.
8. Carcinoma of the stomach following total gastrectomy.
9. Drugs like oral contraceptives, anticonvulsants, anti-tumor agents, and antimicrobial agents.
10. Anemia of hypothyroidism.
11. Postspenectomy.
12. Myelodysplastic syndrome.

What are the causes of decreased MCV?

1. Microcytic anemia where MCV <80 fL and MCHC <30 g/dL).
2. Iron deficiency anemia.
3. Thalassemia.
4. Chronic diseases.
5. Iron deficiency anemia is usually seen in inadequate iron intake, poor absorption, and chronic blood loss.
6. Sideroblastic anemia.
7. Anemia of chronic diseases.
8. Lead poisoning.
9. Disorders of porphyrin synthesis.

What are the causes of normal MCV?

1. Normocytic anemia.
2. Some hemolytic anemia.
3. In some hemoglobinopathies.
4. Hypoplastic and aplastic marrow.

Mean corpuscular hemoglobin (MCH):

How will you define MCH?

1. This is the mean of the average amount of hemoglobin in red blood cells or the average weight of hemoglobin in absolute units in the RBCs.
2. The result gives the average hemoglobin content per RBC in picograms (pg).
3. The MCH value is usually higher in newborns and infants because their MCV is higher than that of adults.

What are the Indications of MCH?

1. It has limited value in the differential diagnosis of anemia.
2. It is instrument calibration.

How will you calculate MCH?

• MCH is calculated by multiplying Hb g/dl x 10 and dividing by the RBC count.

• Generally, macrocytes have more hemoglobin, and microcytes have less, so the values resemble those of MCV.

What factors interfere with the estimation of MCH?

1. Increased white cell count increases the MCH value.
2. Cold agglutinins increase the MCH value.
3. Lipemia increases the MCH value.
4. High concentrations of heparin increase the MCH value.
5. Monoclonal immunoglobulin increases the MCH value.
6. In vivo, hemolysis increases the MCH value.

What is the normal MCH value?

• Adult (all ages) = 27 to 31 pg
• Newborn = 32 to 34 pg

What are the causes of increased MCH?

1. Macrocytic anemias.
2. Newborn.

What are the causes of decreased MCH?

1. Microcytic anemias.
2. Hypochromic anemia.

Mean corpuscular hemoglobin concentration (MCHC):

How will you define MCHC?

1. This is the average concentration or percentage of hemoglobin in each red blood cell.
   1. It is the ratio of the weight of hemoglobin to the volume of the RBCs.
2. MCHC is the most useful for monitoring the treatment of anemia.

What are the indications of the MCHC?

1. It is better than MCH to identify hypochromasia.
2. Changes in the MCHC appear late in iron deficiency anemia (severe cases).
3. It is instrument calibration.

How will you calculate MCHC?

1. This is calculated by hemoglobin x 100 divided by hematocrit.
2. It is the average amount of Hemoglobin per RBcs (33 to 37 g/dL).

What is normal MCHC?

• Adults of all ages = 32 to 36 g /dl (32 to 36%)
• Newborn = 32 to 33 g /dl (32 to 33%)

How are Red Blood Cells classified based on MCHC?

1. Hypochromic When MCHC is decreased, hemoglobin deficiency occurs, e.g., in iron deficiency anemia and thalassemia.
2. Normochromic when the values are normal (In hemolytic anemia).
3. Hyperchromic when MCHC value is increased, and RBC cannot accommodate more than 37 g/dl (seen in spherocytosis, newborns, and infants).

What are the causes of increased MCHC?

1. Spherocytosis.
2. Newborns and infants.

What are the causes of decreased MCHC?

1. Iron deficiency anemia.
2. Thalassemia.
3. Microcytic anemia with chronic blood loss.

Red blood cell distribution width (RDW):

How will you define RDW?

1. RDW is the quantitative measure of anisocytosis.
2. This is the coefficient of the RBC volume distribution.
3. This indicates variation in the size of RBC.
4. The machine calculates this using MCV and RBC values.
5. This is helpful for the diagnosis of hematological disorders and monitoring the response to therapy.
6. This is also helpful in distinguishing iron-deficiency anemia (RDW increased) from hemoglobinopathies (RDW normal).

What are the Indications for RDW?

1. RDW is used to classify the anemias based on MCv and RDW.
2. RDW is more sensitive in microcytic than macrocytic RBC conditions.
3. RDW is not helpful in cases without anemia.

How will you calculate RDW?

Red Blood cell Indices: RDW formula and calculation

What is normal RDW?

• Adult = 11.5% to 14.5%

Classify Anemias based on cell size (MCV), and (MCH)?

How will you classify anemias based on MCV and MCHC?

Questions and answers: