What is the Difference Between PCV and ESR

The main difference between PCV and ESR is that PCV is the measurement of the proportion of blood that is made up of cells, whereas ESR is the rate of sedimentation of red blood cells in anticoagulant blood.

PCV and ESR are two types of hematology tests that are important for the study of the cause, prognosis, treatment, and prevention of diseases. Both tests involve measuring the red blood cells in the blood.

Key Areas Covered

1. What is PCV
     – Definition, Features, Importance
2. What is ESR
     – Definition, Features, Importance
3. Similarities Between PCV and ESR
     – Outline of Common Features
4. Difference Between PCV and ESR
     – Comparison of Key Differences

Key Terms

ESR, Erythrocyte Sedimentation Rate, PCV, Packed Cell Volume

What is PCV

PCV, or packed cell volume, is the proportion of blood made up of blood cells. Generally, the value comes as a percentage or fraction of cells. Red blood cells account for nearly all of the blood cells in the blood. Therefore, PCV increases with the increase of the number of red blood cells while it decreases with the reduction of the total volume of blood. Moreover, PCV decreases in anemia when the number of red blood cells decreases in comparison to the normal value. The reduction of red blood cell production or the increase of the destruction of red blood cells also causes anemia.

Figure 1: PCV

Furthermore, the number of red blood cells increases in polycythemia. Meanwhile, dehydration results in the reduction of the total volume of the blood. However, hemodilution causes an increase in the total volume of blood, as in pregnancy. On the other hand, PCV is a part of full blood count (FBC), and the test is repeated in many conditions, including anemia, polycythemia, dehydration, monitoring the effectiveness of blood transfusions, and monitoring ongoing bleeding.

What is ESR

ESR or erythrocyte sedimentation rate is the rate at which the red blood cells descend over a period of one hour in anticoagulated whole blood in a standardized tube known as a Westergren tube. Normally, the test measures the distance of red blood cells in the tube, and it comes in millimeters. Additionally, it is important for the non-specific measure of inflammation. ESR especially increases inflammation, anemia, pregnancy, infections, autoimmune disorders, kidney diseases, and in cancers.

Figure 2: ESR

Moreover, when inflammation is present, blood contains a high proportion of fibrinogen. Here, fibrinogen serves as a pro-sedimentation factor that sticks red blood cells to each other. Usually, this results in an increase in the sedimentation rate of red blood cells due to the increase in density. Apart from that, rouleaux refers to the forming of red blood cell stacks. In comparison, ESR decreases in leukemia, polycythemia, sickle cell anemia, hyperviscosity, chronic fatigue syndrome, congestive heart failure, and low plasma protein.  

Similarities Between PCV and ESR

• PCV and ESR are two types of hematology tests used to study the cause, prognosis, treatment, and prevention of diseases.
• They are important for diagnosing diseases related to the production of blood cells, hemoglobin, blood proteins, etc.
• Both PCV and ESR involve in measuring red blood cells in the blood.

Difference Between PCV and ESR

Definition

PCV refers to the proportion of blood occupied by red blood cells, usually expressed as a percentage of the total blood volume, while ESR refers to a blood test that can show if you have inflammation in your body.

Significance

PCV is the proportion of blood made up of blood cells, while ESR is the rate at which red blood cells descend over a period of one hour.

Measurement

Moreover, PCV measures the volume of red blood cells, while ESR measures the density of red blood cells.

Increases in

PCV increases in polycythemia, while ESR increases in inflammation, anemia, pregnancy, infections, autoimmune disorders, kidney diseases, and in cancers.

Decreases in

PCV decreases in anemia, dehydration, and hemodilution, while ESR decreases in leukemia, polycythemia, sickle cell anemia, hyperviscosity, chronic fatigue syndrome, congestive heart failure, and low plasma protein.  

Conclusion                                                                                                                

In brief, PCV and ESR are two types of blood tests that significantly measure red blood cells. Generally, PCV measures the proportion of blood occupied by red blood cells. Therefore, it measures the volume of red blood cells in the blood. Significantly, PCV is important in diagnosing anemia, polycythemia, and dehydration. In comparison, ESR is the rate at which red blood cells descend over a period of one hour. Hence, it measures the density of red blood cells. On the other hand, ESR is important for the non-specific measure of inflammation. On that account, the main difference between PCV and ESR is their type of measurement.      

References:                

1. “PCV.” Understand the Test. Lab Test Online.
2. “Erythrocyte sedimentation rate.” Wikipedia. Wikimedia Foundation.

Image Courtesy:

1. “Anatomy and physiology of animals Packed cell volume of blood” By Adrignola – Own work (CC BY 3.0) via Commons Wikimedia
2. “StaRRsed pipet array” By MechESR – Own Work (CC0) via Commons Wikimedia