Health

Health check: What is Anemia?

Anemia can be described as a reduction in the oxygen-carrying capacity of the blood. This is usually caused by a decrease in the levels of red blood cells. This causes a reduction in the ratio of the volume of RBC and a general decrease in hemoglobin.  Hemoglobin is a protein that is responsible for transporting oxygen in the blood. It is a molecule that is comprised of four subunits, each containing an iron atom bound to a haem group. The most common cause of anemia is due to iron deficiency. The body needs iron to make hemoglobin, if there is not enough iron, hemoglobin cannot be made. Anemia has three main causes, these include; blood loss, lack of red blood cell production and high rates of red blood cell destruction. Blood loss can lead to a condition called erythroid hyperplasia, which is a condition of excessive immature red blood cells. Erythroid hyperplasia is usually a compensatory condition which can be due to hemolytic anemia, iron deficiency anemia, thalassemia, thrombotic thrombocytopenic purpura (TTP) and erythromyeloid.  Loss of blood can be acute or chronic, in acute blood loss, if the person survives, the marrow replaces the RBC. Chronic is long-term anemia that happens when the Iron levels are depleted. This can happen as a result of GI bleeds (Anemia, 2019).


    Individuals can also develop anemias from the reduced production of RBC (erythropoiesis). These types of anemias arise as a result of a deficiency in substrates necessary for RBC production. For example, Megaloblastic anemias, arise from folate and vitamin B12 deficiency. They are characterized by the presence of megaloblasts in the bone marrow and macrocytes in the blood.  Megaloblastic anemia can also result from rare inborn errors of metabolism of folate and vitamin B12.  Symptoms include; muscle weakness, abnormal pale skin, swollen tongue, loss of appetite and a fast heart rate. Another example is pernicious anemia. Pernicious anemia results from lack of intrinsic factors that are normally produced by the parietal cells in the stomach. Intrinsic factors are important for the body’s synthesis of B12. Lack of Intrinsic factors is probably due to the autoimmune response to parietal cells.  Vitamin B12 is a water-soluble substance that is present naturally in some food and available as dietary supplements and prescription medication. Vitamin B12 exists in several forms and contains the mineral cobalt. B12 is required for proper RBC formation, neurological function and DNA synthesis. Vitamin B12 that is bound to protein is released by the action of hydrochloric acid and gastric protease in the stomach. When Vitamin B12 is added to fortified foods and dietary supplements, it is already in free form and does not require this separation step.  The main causes of vitamin B12 deficiency include; vitamin B12 malabsorption from food, postsurgical malabsorption and pernicious anemia (Office of Dietary Supplements – Vitamin B12, 2020).  


Types of Anemia

Hemolytic Anemia

    This type of anemia is caused by the destruction of the RBC prematurely. There are several types of hemolytic anemias, diagnosis is based on the underlying cause. Conditions that can lead to fast destruction of RBC include; sickle cell anemias, thalassemia and bone marrow failure. Also, it can be as a side effect of blood transfusion and medications such as cephalosporins, levodopa, levofloxacin and non-steroidal anti-inflammatory can cause hemolytic anemia.  Hemolytic anemia can develop suddenly or slowly, it can range from mild to severe. Signs and symptoms include; fatigue, dizziness, heart palpitation, pale skin, headaches, confusion, jaundice and enlargement of the spleen or liver (Drug-Induced Immune Hemolytic Anemia, 2019).  


Hereditary Spherocytosis

This is an autosomal dominant disorder, resulting in membrane defects or reduction in protein that codes for spectrin. Spectrin is a cytoskeletal protein that lines the intracellular side in eukaryotic cells. RBCs become spherical, less deformable and are more prone to destruction in the spleen. The cells lose their membranes spontaneously which results in them becoming spherical. They appear as small cells with small central areas missing when the cells are stained. There are four forms of hereditary spherocytosis, which are distinguished by the severity of symptoms. They are known as mild form, moderate form, moderate/severe form and the severe form (Hereditary Spherocytosis, 2019).


Sickle Cell Anemia

   This is a hereditary disease due to point mutation; the RBCs appear sickle shaped. This results in the chronic hemolytic state. The cell membrane is rigid and non-deformable. Results in the sickle cells being destroyed in the spleen. The average survival days of the sickle cells is 20 days, normal RBC lifespan is 115 days.   Microvascular occlusions also happen because the membrane is not elastic. This increases the chances of the RBC’s adherence to the endothelium of the capillaries which then cause blockage of the small vessels.

    The severity of symptoms will vary from person to person. Sickle cell anemia can lead to various serious acute and chronic conditions. For example, hemolytic crisis happens when there is an accelerated drop in the levels of hemoglobin, this is particularly common in people with coexisting G6PD deficiency. G6PD is an enzyme designed to produce reduced glutathione in the RBC monophosphate hexose pathway. Glutathione aids in the prevention of oxidative damage to the hemoglobin and other intracellular structures. Sickle cell anemia is most common in black people (Pernicious Anemia | National Heart, Lung, and Blood Institute (NHLBI), 2019).


Aplastic Anemia 

Happens because of damage to the stem cells inside the bone marrow, aplastic anemia can happen suddenly or slowly and can be mild or severe. Risk factors include; genetics, some medications and certain environmental toxins. The low levels of blood cells increase the likelihood of developing complications such as arrhythmias and heart failure. Other symptoms include; fatigue, easy bruising and infections that last for along time.  Treatment depends on the underlying cause, it may include; immunosuppressants, blood transfusion and bone marrow transplants (Aplastic Anemia | National Heart, Lung, and Blood Institute (NHLBI), 2019).  


References

Hanna, J., Wernig, M., Markoulaki, S., Sun, C.-W., Meissner, A., Cassady, J. P., . . . Jaenisch, R. (2007). Treatment of Sickle Cell Anemia Mouse Model with iPS Cells Generated from Autologous Skin. Science, 318(5858), 1920-1923. doi:10.1126/science.1152092

Fitzsimons, E. J., & Brock, J. H. (2001). The anaemia of chronic disease: Remains hard to distinguish from iron deficiency anaemia in some cases. BMJ: British Medical Journal322(7290), 811.

Beutler, E., & West, C. (2005). Hematologic differences between African-Americans and whites: the roles of iron deficiency and α-thalassemia on haemoglobin levels and mean corpuscular volume. Blood106(2), 740–745. http://doi.org/10.1182/blood-2005-02-0713

Anemia. (2019). [Text]. National Library of Medicine. Retrieved June 11, 2020, from https://medlineplus.gov/anemia.html

Aplastic Anemia | National Heart, Lung, and Blood Institute (NHLBI). (n.d.). Retrieved June 11, 2020, from https://www.nhlbi.nih.gov/health-topics/aplastic-anemia

Drug-induced immune hemolytic anemia: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved June 11, 2020, from https://medlineplus.gov/ency/article/000578.htm

Office of Dietary Supplements—Vitamin B12. (n.d.). Retrieved June 11, 2020, from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

Pernicious Anemia | National Heart, Lung, and Blood Institute (NHLBI). (n.d.). Retrieved June 11, 2020, from https://www.nhlbi.nih.gov/health-topics/pernicious-anemia

Reference, G. H. (2019.). Hereditary spherocytosis. Genetics Home Reference. Retrieved June 11, 2020, from https://ghr.nlm.nih.gov/condition/hereditary-spherocytosis


Part one

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