Anemia is associated with a decrease in red blood cells, or hemoglobin concentration. Ways of classifying anemia depend on the size and hemoglobin content of the red blood cells (morphological) or the mechanism (pathophysiological).
If you have ever uttered the phrase, ‘I’m so tired!’ to a friend or coworker, I am sure your comment was met with a sympathetic pat on the back.
We all live hectic lives and very few of us escape the occasional bout with fatigue. However, utter this same phrase to your doctor and you might be met with the prick of a needle as your doctor performs a blood test to determine if you have one of the most common causes of fatigue, known as anemia.Anemia results when there is a deficiency of red blood cells or a decreased amount of hemoglobin. This diminishes the blood’s ability to carry oxygen and leads to symptoms like fatigue, lightheadedness, and shortness of breath.In this lesson we will look at how disorders associated with anemia are classified, but classification of anemia is a pretty broad topic, so it will be helpful for us to take a moment to understand a couple of terms.
We just learned that anemia has to do with your red blood cells.
In physiology, we use the term ‘cyte’ when referring to a cell. In fact, ‘erythrocyte’ is the fancy term for a red blood cell.We also mentioned that anemia has a lot to do with the oxygen-carrying pigment of the red blood cell known as hemoglobin. In physiology, the term ‘chroma’ is often used in association with hemoglobin. Chroma is the Greek word for color, and it is associated with hemoglobin because hemoglobin bound to oxygen is what gives your blood its bright red color.Okay, great! Let’s look at a few more terms that will come in handy. Some classifications of anemia deal with the size or volume of the red blood cell, so we use prefixes such as ‘normo’ to mean normal, ‘micro’ to mean small and ‘macro’ to mean large.
The hemoglobin content of the red blood cell can also be a factor with anemia. We already learned that the prefix ‘normo’ means normal, so that’s easy. We also use the prefix ‘hypo’ when referring to a quantity that is low and the prefix ‘hyper’ when the quantity is high. That simple little terminology lesson can now help us with our understanding of the classifications of anemia.
Anemia is classified in two ways, either morphological classification or pathophysiological classification. The morphological classification is based on the size or volume of the red blood cell and may also be classified by the hemoglobin content of the red blood cell. A red blood cell of a normal size or volume is said to be normocytic.With our earlier terminology lesson this term becomes easy to recall. With this understanding it is easy to see that if the cell volume is decreased, then we will have an abnormally small cell, or it is said to be microcytic, and if the volume is increased, we will have an abnormally large cell, and we can use the term macrocytic.
A morphological classification of anemia can also be normochromic, which we know from our terminology lesson means red blood cells with normal hemoglobin content. Or they could be hypochromic, meaning low hemoglobin content, or hyperchromic, meaning high hemoglobin content.At this point you might be wondering why we would go to so much trouble to try and classify anemias.
The reason is because categorizing an anemia is useful in determining what is going on in the body and, therefore, defining the underlying condition. For example, if tests reveal small red blood cells (microcytic) and low hemoglobin content (hypochromic), then the physician would have a good indication that this patient might be dealing with iron-deficiency anemia and could prescribe an appropriate treatment plan. It might help you to recall this fact by remembering that iron helps make blood cells, so if iron is deficient, then the cell volume and hemoglobin will be deficient, giving us microcytic, hypochromic cells.
On the other hand, if the tests reveal large red blood cells (macrocytic) along with a normal hemoglobin concentration (normochromic), then the physician might suspect a deficiency of B12 or folic acid as the underlying condition.
Anemia is also classified through pathophysiological classification. This classification is based on anemia due either to increased loss or destruction of red blood cells or a decreased production of red blood cells.
Now we know that pathophysiology is the study of changes associated with a disease. So for this classification system, looking at what has changed in the patient’s recent clinical history is very helpful.For example, if a person has a recent history of hemorrhaging, or acute blood loss, then the pathophysiological classification would be due to increased loss of red blood cells. On the other hand, if the person was recently exposed to a toxin, like benzene, which is known to result in bone marrow failure, then it would be suspected that the anemia would be due to a decreased production of red blood cells, since red blood cells are made in the bone marrow.
Let’s review…Anemia is classified by morphology or pathophysiology. The morphological classification is based partly on the size or volume of the red blood cell. Normocytic would indicate a red blood cell of a normal size or volume.
Microcytic indicates an abnormally small cell, and macrocytic indicates an abnormally large cell. Morphological classification is also based on the hemoglobin content of the red blood cell. Normochromic means a red blood cell with normal hemoglobin content, hypochromic means low hemoglobin content and hyperchromic means high hemoglobin content.
Categorizing an anemia based on morphology is useful in determining the underlying condition. For example, microcytic, hypochromic cells are seen in iron-deficiency anemia, and macrocytic, normochromic cells are characteristic of a deficiency of B12 or folic acid.Pathophysiological classification is based on either anemia due to increased loss or destruction of red blood cells as would be expected in a person with a recent history of hemorrhaging, or a decreased production of red blood cells as would be expected in a person experiencing bone marrow failure.
Upon completing this video lesson, you might be able to define anemia and understand its causes.
You could have the ability to classify different types of anemia and determine what might occur in the body in each instance.