What is anemia?

We talk about an anemia when the concentration of hemoglobin drops under the normal range for a person with the age, sex and geographic location. At sealevel, the hemoglobin lower limit is considered to be 14 g/dL for an adult man and 12 g/dL for an adult woman. Anemia isn’t a diagnosis in itself, but always indicates an underlying affliction.

What are the causes of anemia?

A low hemoglobin level can be caused by a lower production rate of red blood cells, a higher destruction rate of red blood cells, a lot of blood loss or fluid overload.

1. Impaired production of red blood cells

This happens when the production of red blood cells can’t compensate the normal destruction of red blood cells. Probably the most common cause of impaired red blood cell production is iron deficiency. Hemoglobin contains iron atoms so it seems logical that when there’s not enough iron, there will be a lack of hemoglobin and this will cause anemia. In fact, each deficiency of resources needed for the production of red blood cells can cause anemia. In addition  to iron, they include folic acid (vitamin B9) and vitamin B12.

2. Increased destruction of red blood cells or “hemolytic anemia”

An early destruction of the red blood cells is indicated by the term hemolysis. By hemolytic anemia we then understand the condition in which the destruction rate of red blood cells has increased whereas the red bone marrow cannot compensate the lack of red blood cells. Hemolytic anemia can be classified as congenital/hereditary hemolytic anemia or acquired hemolytic anemia:

• Hereditary hemolytic anemia is an inherited anemia existing at birth or even before birth. It can be due to defects in the production of the red blood cell membrane, defects in hemoglobin production (ex. thalassemia and sickle-cell disease) or defects in the energy production of red blood cells (ex. pyruvate kinase deficiency and G6PD deficiency)
• Acquired hemolytic anemia can occur throughout life and isn’t inherited. It may be caused by immune-mediated causes, drugs and other miscellaneous causes.

3. Blood loss

Blood loss can also cause anemia. This can occur after a trauma or surgery causing acute blood loss, as well as from menstruation.

4. Fluid overload

When the blood volume increases, the blood will be diluted and thus the concentration of hemoglobin will decrease. For example, during pregnancy the blood volume will expand which can lead to a pregnancy anemia.

” When I tell someone I have anemia, people tell me I should take iron supplements. I always have to explain that a lack of iron isn’t the cause of my anemia: I produce enough red blood cells, they just die faster than those of an average person.”
Female, 28 years

Learn more about the hemolytic anemia caused by Pyruvate Kinase deficiency.

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