Anemia

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anemia

What anemia is:

Anemia is a medical term for low hemoglobin content in the blood. Hemoglobin is a protein molecule in red blood cells  (RBCs) that carry oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs.

Human beings can suffer from many different types of anemia. The most common type of anemia is iron deficiency anemia.

Anemia can be caused by one of three mechanisms (described in detail below).

  1. Deficiency in red cell production
  2. Increase in red cell destruction
  3. Blood loss

Symptoms:

Individuals who suffer from anemia may complain about feeling weak, tired, or having headaches or vertigo. They may experience shortness of breath on exertion, heart pain, muscle weakness and skin problems like loss of elasticity.

Various types of anemias cause different symptoms and certain signs are specific to certain anemias.

Spoon shaped nails and smooth glossy tongue are signs of severe iron deficiency anemia. Severe bone/muscle pain may be due to sickle cell anemia. Dark brown urine in the morning may be due to paroxysmal nocturnal hemoglobinuria.

Causes and risk factors:

Anemia can be divided into three categories.

  1. Deficiency in red cell production: In this category, the human body lacks the building blocks to make blood cells. Examples include:
  • Iron deficiency anemia: low iron availability
  • Aplastic anemia: damage occurs to your bone marrow, slowing or shutting down the production of new blood cells
  • Sideroblastic anemia: bone marrow produces ringed sideroblasts rather than healthy biconcaved red blood cells. The body has iron available but cannot incorporate it into hemoglobin, which red blood cells need to transport oxygen efficiently.
  • Anemia of chronic disease: a form of anemia seen in chronic infection, chronic auto immune disease, and malignancy. The body has iron in storage but prevents its release.
  • Megaloblastic anemia: Lack of vitamin B12 or folate.
  1. Increase in red cell destruction. In this category, the human body makes red cells, however the cells are being destroyed. This may happen inside the blood vessel (intrinsic) or outside the blood vessel (extrinsic). Examples include:
  • Intrinsic causes
    Hereditary spherocytosis or hereditary elliptocytosis: Defects in cell membrane production. The cell doesn’t develop into a normal biconcave disc and the body destroys it because of its abnormality.

    Thalassemia, Sickle cell disease: defects in hemoglobin production due to genetic defects. For example sickle cell patients have mutations in the haemoglobin beta (HBB) gene on chromosome 11. Creating abnormal versions of beta-globin which distort red blood cells into a sickle shape. The sickle-shaped red blood cells die prematurely, which can lead to anemia.

    Glucose-6-phosphate dehydrogenase deficiency (G6PD) and pyruvate kinase deficiency: a defect in enzymes called glucose-6-phosphate dehydrogenase or pyruvate kinase, which causes red blood cells to break down prematurely.

  • Extrinsic causes
    Autoimmune diseases: may cause the production of antibodies which attack the red blood cells

    Paroxysmal nocturnal hemoglobinuria: Red blood cells lack the main proteins that protect blood cells from destruction, decay-accelerating factor (DAF/CD55), and without this protection are prone to destruction.

    Drugs or toxins: There are many drugs or toxins which can damage blood cells. Well-known examples include penicillin, anti-malarial drugs and snake bites. Note: that the list of drugs and toxins is too large to discuss here.

    Spleen: The spleen helps filter old and damaged cells from your bloodstream. If your spleen is overactive, it removes the blood cells too early and too quickly.

    Low-grade hemolytic anemia occurs in 70% of prosthetic heart valve recipients, and severe hemolytic anemia occurs in 3%. The RBCs shear against the prosthetic valves, causing destruction.

  1. Blood loss: Acute (fast) or Chronic (slow)
  • Acute: anemia can develop rapidly from a sudden loss of blood, such as from bodily injury, surgery, childbirth, or a ruptured blood vessel. Losing large amounts of blood suddenly can create two problems; adrop in blood pressure because the amount of fluid left in the blood vessels is insufficient, and secondly, the body’s oxygen supply is drastically reduced because the number of oxygen-carrying red blood cells has decreased so quickly. Either problem may lead to a heart attack, stroke, or death.
  • Chronic: If a small amount of bleeding continues for a long time, a significant amount of blood may be lost over time. Such gradual bleeding may occur with common disorders, such as ulcers in the stomach or small intestine, polyps, diverticulosis or cancers in the gastrointestinal tract. Other sources of chronic bleeding include kidney or bladder tumours, which may cause blood to be lost in the urine, and heavy menstrual bleeding due to fibroids or endometrial carcinomas.

How it is diagnosed:

To diagnose anemia, your doctor may ask you about your medical and family history, perform a physical exam, and run the following tests:

  1. Complete blood count (CBC). A CBC is used to count the number of blood cells in a sample of your blood. According to the Canadian Blood Services, normal hemoglobin for a male is 140 g/L to 180 g/L, and for a non pregnant female, 120 g/L to 160 g/L.
  2. A test to determine the size and shape of your red blood cells.
  3. Hemoglobin electrophoresis to identify the different types of hemoglobin in your bloodstream. This is usually for suspected genetic blood abnormalities.

Complications:

A treatment plan should be discussed with your family doctor or hematologist to determine the best plan of action to eradicate and/or control the anemia. Mild anemia may be manageable however if your body’s organs do not get enough oxygen, there might be severe consequences. In some cases, the underlying cause of the anemia may be deadly and painful.

Treatments:

Treatments vary depending on the type of anemia being treated. Treatments may include, drinking more fluids, iron supplementation for iron deficiency anemia, blood transfusions for blood loss and prescription medications.

Written by: Vanora D’Sa MD

 

References

  1. Raw, Isaias. (1975). Anemia: From Molecule to Medicine. New York, New York: Little, Brown and Company (Inc).
  2. Irwin, Weinstein., Beutler, Ernest. (1962). Mechanisms of Anemia. New York, New York: McGraw-Hill Book Company, Inc.
  3. Website: http://www.webmd.com/a-to-z-guides/understanding-anemia-basics#1
  4. Website: https://en.wikipedia.org/wiki/Anemia
  5. Website: http://emedicine.medscape.com/article/207468-overview
  6. Website: http://www.medicinenet.com/hemoglobin/article.htm
  7. Website: http://www.mayoclinic.org/diseases-conditions/aplastic-anemia/symptoms-causes/dxc-20266535
  8. Website: https://blood.ca/en/blood/hemoglobin