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Things You Should Know About Anemia

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Anemia results in lack of energy

In our blood, there are basically three different types of cells: red blood cells (RBC), white blood cells (WBC), and platelets.  Among them, red blood cells are the ones that contain a protein called hemoglobin that carries oxygen to tissues. Anemia is defined as a decrease in the amount of hemoglobin below the reference range appropriate for a particular age and gender. Anemia itself is not a disease but is an indicator of any underlying health problems.

Causes and Risk Factors of Anemia

Some causes of decreased production of RBCs are as follows:
  1. Lack of iron, vitamin B12, or folate in the diet
  2. Chronic diseases such as rheumatoid arthritis, infection, or cancer
  3. Invasion of bone marrow by cancer
  4. Kidney failure

Iron deficiency is the most common cause of anemia worldwide. 

Causes of anemia due to loss of RBCs are:
1. Decreased circulating blood volume due to trauma, heavy menstrual bleeding in premenopausal women, ingestion of drugs causing blood loss from the gut (e.g. aspirin and NSAIDs). 

2. Destruction of RBCs: Destruction of RBCs results in a condition known as hemolytic anemia. This destruction of RBCs may occur either inside or outside the blood vessels. The cause of hemolysis may be mechanical from trauma to RBCs as they pass through narrow blood vessels, from antibodies attacking RBCs, or due to destruction of RBCs as they pass through narrow spaces in the spleen.

3. Inherited Blood Disorders: Some genetic conditions causing anemia are sickle cell anemia, thalassemia, hereditary spherocytosis, Fanconi anemia, etc. These types of anemia are highly prevalent in certain ethnic groups due to incestuous marriage. 

4. Physiological anemia: In pregnancy, anemia may be seen even in normal conditions due to dilution of RBCs because of increased plasma expansion.

Clinical Features of Anemia

The development of symptoms depends on the rapidity of onset of anemia. Rapid blood loss from the body for instance in trauma causes more profound symptoms than a gradually developing anemia from a chronic illness. Patients may report shortness of breath on exertion, easy fatigue, and lack of energy. If anemia is associated with an underlying heart or lung disease, then symptoms may be elicited even with a mild fall in hemoglobin level. Patients with long-standing B12 deficiency may demonstrate features of nerve damage like tingling sensation and sensory or motor problems in limbs.

Diagnosis of Anemia

For diagnosis of anemia, physicians obtain a detailed patient history inquiring them about their diet, alcohol intake, family history of anemia, and whether they are taking any drug. 
  • Complete blood count (CBC): It is done to evaluate the degree of anemia and it also gives clues to the underlying cause. For e.g. In a disease called aplastic anemia, production of all types of blood cells is decreased. 
  • Peripheral blood smear (PBS): Examining the shape and size of blood cells under a microscope is called peripheral blood smear. It is done to evaluate the underlying etiology.
  • Reticulocytes: Immature or just born RBCs are called reticulocytes. It gives physicians an idea of whether the underlying defect is in bone marrow or elsewhere. The level of reticulocytes is decreased if the bone marrow is not functioning properly.
  • Iron level: The level of iron in the blood is evaluated using several tests such as serum ferritin, transferrin saturation, and total iron-binding capacity
  • Vitamin B12 level in the blood
  • Bone marrow biopsy: Bone marrow is aspirated with a needle and examined under the microscope to evaluate any defect. This investigation is a must if any type of blood cancer is suspected.
  • Hemoglobin electrophoresis: This is a test to evaluate defects in hemoglobin like sickle cell anemia, hemoglobin C disease, etc. 
 

Management for Anemia

Management of Anemia chiefly entails treating the underlying cause of anemia in addition to symptomatic treatment. If anemia is due to iron deficiency, then supplemental iron may be prescribed by the physician and if the cause is a deficiency of vitamin 12 or folate, then those vitamins may be supplemented as per the physician's advice. If a person has recently traveled to developing countries, then investigations to rule out a parasitic disease like hookworm may be done as the causative agent for anemia. 

In cases of anemia resulting from genetic diseases such as sickle cell anemia or thalassemia, a blood transfusion may be needed if significant symptoms are present or if hemoglobin is less than 7g/dl. Chelation therapy may also be done for these cases to reduce iron overload from frequent blood transfusion. Hematopoietic stem cell transplantation (HSCT) is an alternative treatment option for some inherited blood disorders. HSCT is the transplantation of blood-producing stem cells, which may be derived from bone marrow, peripheral blood, or umbilical cord.

Ongoing Research on Novel Treatments for Anemia

  • Effect of Vitamin C on anemia in pregnancy: When used in addition to iron, vitamin C has been known to improve outcomes in anemia; however few studies have been done to examine the benefits of Vitamin C in pregnancy. A clinical trial is currently ongoing to evaluate the effect of vitamin C on anemia in pregnancy.
  • Intravenous infusion of Ferumoxytol compared to oral ferrous sulphate for the treatment of anemia in pregnancy: Researchers are currently studying whether intravenous administration of Ferumoxytol is superior to oral ferrous sulphate for the treatment of iron deficiency anemia in pregnancy.
  • A clinical trial is currently underway to assess the efficacy and safety of Ferric carboxymaltose in pediatric patients with iron deficiency anemia and unsatisfactory response to oral iron.
  • Gene therapy in adults with sickle cell disease: This is a phase 1 pilot study in adult subjects with severe sickle cell disease. The chief objective of this trial is to evaluate the safety and feasibility of gene therapy in adult subjects with severe sickle cell disease.
  • Acalarutinib for the treatment of relapsed or refractory autoimmune hemolytic anemia (AIHA) in patients with chronic lymphocytic leukemia: This trial is in phase 2 and aims to evaluate the effect of acalarutinib for the treatment of relapsed or refractory AIHA.
  • Roxadustat for the treatment of chemotherapy-induced anemia: Roxadustat is a drug that increases the production of a hormone called erythropoietin which in turn increases the production of RBCs.  The objective of this clinical trial is to assess if roxadustat is safe and effective for the treatment of anemia in people receiving chemotherapy for the treatment of cancer.
 
References
Hillman RS et al: Hematology in Clinical Practice, 5th ed. New York,
McGraw-Hill, 2010

Sankaran VG, Weiss MJ: Anemia: Progress in molecular mechanisms
and therapies. Nat Med 21:221, 2015.

     

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