What is the Difference Between Hemoglobin and Hematocrit

The main difference between hemoglobin and hematocrit is that hemoglobin is the iron-containing protein responsible for carrying oxygen in red blood cells whereas hematocrit is the volume of red blood cells compared to the total blood volume. Furthermore, hemoglobin level for males is 14 to 18 g/dl; that for females is 12 to 16 g/dl while the normal hematocrit for men should be 40 to 54%; for women it should be 36 to 48%. 

Hemoglobin and hematocrit are two important measurements of the oxygen-carrying capacity of the blood. Hematocrit (%) is equal to three times value of hemoglobin (g/dl).

Key Areas Covered

1. What is Hemoglobin
     – Definition, Measurement, Reference Values
2. What is Hematocrit
     – Definition, Measurement, Reference Values
3. What are the Similarities Between Hemoglobin and Hematocrit
     – Outline of Common Features
4. What is the Difference Between Hemoglobin and Hematocrit
     – Comparison of Key Differences

Key Terms

Anemia, Hematocrit, Hemoglobin, Red Blood Cells, Tissue Oxygenation

Difference Between Hemoglobin and Hematocrit - Comparison Summary

What is Hemoglobin

Hemoglobin (Hb) is the iron-containing protein that occurs in red blood cells. Therefore, the main function of hemoglobin is to carry oxygen throughout the body, supplying it to the metabolizing tissues. Thus, sufficient hemoglobin levels should be in the blood for adequate tissue oxygenation. The reference value of hemoglobin is 14 to 18 g/dl in males while 12 to 16 g/dl in females. However, low hemoglobin levels in the blood indicate anemic conditions. On the contrary, high hemoglobin levels can be identified with erythrocytosis, which is a consequence of excessive amounts of red blood cells in the blood.

What is the Difference Between Hemoglobin and Hematocrit

Figure 1: Hemoglobin Structure

Well-mixed EDTA-anticoagulated whole blood is the specimen for measuring the hemoglobin levels in the blood. First, all the hemoglobin in the blood is converted into cyanomethemoglobin, which is then measured by a colorimeter. Also, hemoglobin electrophoresis is another method which measures the mobility of hemoglobin in an electric field.

What is Hematocrit

Hematocrit (Hct) (Ht) is the measurement of the volume of red blood cells with respect to the total volume of blood. Several methods are responsible for measuring hematocrit. The two main methods are the direct measurement of the hematocrit by microhematocrit centrifugation and the calculation of the hematocrit indirectly. Also, automated cell counters can calculate it by multiplying the red cell count (millions/mm3) by the mean corpuscular volume (MCV). Here, MCV is the average volume of a red blood cell.

Difference Between Hemoglobin and Hematocrit

Figure 2: Hematocrit

However, the measurement of hematocrit, as well as the hemoglobin levels, depends on the plasma volume. Both values appear high in severely dehydrated individuals while they become low in individuals overloaded with fluids. In both conditions, in order to assume the normal values, independent radionuclide evaluation of the red cells and plasma has to be performed.

Similarities Between Hemoglobin and Hematocrit

  • Hemoglobin and hematocrit are two measurements of the oxygen-carrying capacity of red blood cells.
  • Whole blood is taken for measuring both hemoglobin levels and the hematocrit. Therefore, both measurements depend on the plasma volume.
  • Furthermore, hematocrit (%) is equal to the three times value of hemoglobin (g/dl).
  • Besides, abnormally low measurements of hemoglobin and hematocrit indicate anemic conditions.

Difference Between Hemoglobin and Hematocrit

Definition

Hemoglobin refers to a red protein responsible for transporting oxygen in the blood of vertebrates while hematocrit refers to the ratio of the volume of red blood cells to the total volume of blood. This is the main difference between hemoglobin and hematocrit.

Measurement

Moreover, hemoglobin tests measure the amount of hemoglobin per unit volume of blood while hematocrit measures the volume of red blood cells with respect to the total blood volume.

Reference Values

Hemoglobin level for males is 14 to 18 g/dl; that for females is 12 to 16 g/dl while the normal hematocrit for men should be 40 to 54%; for women it should be 36 to 48%. This is another difference between hemoglobin and hematocrit.

Anemia

Furthermore, low hemoglobin levels indicate anemia while hematocrit is the quick method to diagnose anemia.

Conclusion

Hemoglobin is the iron-containing protein found in red blood cells. Hemoglobin levels indicate the amount of hemoglobin present per unit volume of blood of a particular individual. In comparison, hematocrit is the volume of red blood cells with respect to the volume of the blood. Therefore, both hemoglobin levels and hematocrit measure the capacity of blood to carry oxygen. However, the main difference between hemoglobin and hematocrit is the type of parameters measured.

References:

1. Billett HH. Hemoglobin and Hematocrit. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 151. Available Here

Image Courtesy:

1. “1904 Hemoglobin” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia  
2. “1901 Composition of Blood” By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia  

About the Author: Lakna

Lakna, a graduate in Molecular Biology and Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things. She has a keen interest in writing articles regarding science.

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