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Anemia is a condition in which the number of red blood cells in the body decreases, hence decreasing the amount of total hemoglobin(a pigment in red blood cells responsible for the gas exchange in cells) and affecting the body’s ability to transport oxygen and carbon dioxide to and from cells. Anemia itself is a medical sign of an underlying etiology or disease-causing it, so it should always be investigated further.


The causes of anemia can be multiple, with three basic mechanisms responsible for it:

  1. Blood loss from the body
  2. Increased destruction of red blood cells, which is also called hemolysis
  3. Decreased production of red blood cells in the body

There are genetic disorders, such as thalassemia, hemoglobinopathies, enzyme abnormalities, hereditary xerocytosis, and Fanconi anemia, in which all three mechanisms cause anemia.

  • Nutritional causes such as vitamin B12 deficiency, iron deficiency, folate deficiency, starvation, and malnutrition cause anemia by decreasing the production of red blood cells in the body.
  • Physical causes such as trauma, burns, frostbite, etc., cause blood loss from the body resulting in anemia.
  • Similarly, chronic diseases like kidney and liver disorders, chronic infections, cancers, and infectious diseases also cause anemia.
  • Certain drugs such as anti-cancer (cytotoxic medicines) also cause anemia by causing bone marrow depression.



Following are the main types of anemia:

  • Iron Deficiency Anemia this is caused by deficiency of iron in the body; iron is the main element needed to synthesize hemoglobin in the bone marrow.
  • Vitamin Deficiency Anemia is known as Pernicious Anemia caused by the deficiency of folate and vitamin B12.
  • Anemia of Chronic Diseasesdiseases such as HIV/AIDS, rheumatoid arthritis, Crohn’s disease can interfere with the production of red blood cells.
  • Aplastic Anemiathis is a rare form of life-threatening anemia in which the body does not produce enough blood cells; causes of aplastic anemia are infections, drugs, and exposure to certain chemicals.
  • Anemia Associated with Bone Marrow Disease- this usually occurs in cancerous conditions.
  •  Hemolytic Anemias- this develops when the rate of destruction of red blood cells is greater than the rate of production by the bone marrow, as seen in certain genetic conditions.
  • Sickle Cell Anemiaa type of hemolytic anemia in which red blood cells assume a sickle-shaped cell and die prematurely.


Epidemiology and Risk Factors

Race: Certain genetic disorders such as hemoglobinopathies and thalassemia are more prevalent in some racial groups, such as Sicilians, making them more susceptible to anemia.

Socioeconomic Status: Socioeconomic conditions in developing countries are another factor. The frequency of nutritional deficiencies and even chronic infectious disorders such as tuberculosis, malaria, AIDS, etc., in these countries, is more than in developed countries.

Sex: Overall, the incidence of anemia is twice as high in females compared to males. The prevalence is more during childbearing age because of pregnancy and related complications during childbirth. Acute anemia due to traumatic causes is more prevalent in males.

Age: Genetically acquired anemias are more common in children. Acute anemia is more common in young adults with a higher incidence of trauma in this age group. Women in their childbearing age are more likely to suffer from iron-deficiency anemia. Anemia of chronic illnesses is more common during the older periods. The use of certain drugs such as aspirin and other non-steroidal anti-inflammatory drugs (NSAIDS) also increases with age, making drug-related anemias in that age group more common.


Signs and Symptoms

Following are the signs and symptoms of anemia:

  • Pallor
  • Weakness and fatigue
  • Shortness of breath
  • Cold extremities
  • Chest pain or generalized body pains
  • Increased heartbeat


The World Health Organization (WHO) criteria for anemia in adults is hemoglobin levels less than 13.5 g/dL for males and less than 12.5 g/dL for females.

To differentiate between different types of anemia, specific investigations are done. These include:

  • Complete blood count with peripheral smear
  • Serum iron
  • Total iron-binding capacity (TIBC)
  • Bone marrow iron
  • Vitamin B12 or folic acid levels
  • Electrophoresis of hemoglobin
  • Bone marrow aspiration and biopsy
  • Specific RBC enzyme essay


Differential Diagnosis

Differential diagnosis involves confirming anemia as the signs and symptoms of various types are interchangeable. These include:

  • Aplastic anemia
  • Pernicious anemia
  • Sickle cell disease
  • Thalassemia
  • Iron deficiency anemia
  • Hemolytic anemia
  • Megaloblastic anemia


Treatment pathways are chosen according to the type of anemia.

  • Blood transfusion is done for patients actively bleeding with critically low hemoglobin levels in the blood.
  •  Corticosteroids are given to patients with autoimmune anemia.
  • For patients with hereditary pathology, splenectomy is usually beneficial.
  • Where blood loss is the causing factor, surgery can be done for gastrointestinal bleeding or bleeding during obstetric complications.
  • Iron supplementation is given for anemia due to blood loss and iron deficiency anemia.
  • Drugs and chemicals causing destroying blood cells are avoided.
  • Nutritional therapy replaces the body’s iron, B12 and folate levels. Meat and leafy vegetables are recommended for this group of patients.
  • Bone marrow and stem cell transplants are done for aplastic diseases such as multiple myeloma, Hodgkin’s lymphoma, leukemia, etc.


Medications used for anemia include:

  • Blood and blood products such as whole blood, fresh frozen plasma, cryoprecipitate, etc.
  • Iron products such as ferrous sulfate, iron chews, iron dextran complex, injectable iron, etc.
  • Mineral and vitamin supplements such as folic acid and vitamin K and electrolyte supplements
  • Vasopressors
  • Histamine antagonists
  • Glucocorticoids


Prognosis depends on the underlying cause of anemia. It is also affected by the following factors:

  • Severity of anemia
  • Age of the patient
  • Existence of other comorbid conditions


Anemia can be prevented by:

  • Eating healthy foods that provide sufficient amounts of iron, folate, vitamin B12, etc. These include meat and meat products, legumes, lentils and beans, citrus fruits, and vitamin C-containing products such as peppers and tomatoes to improve iron absorption in the body.
  • Drinking enough water to stay hydrated.
  • Exercising regularly.
  • Avoid long-term exposure to harmful drugs and chemicals that destroy red blood cells.
  • Practicing hand hygiene to avoid infections.
  • Regular screening for genetic disorders prevalent in the family, such as thalassemia and sickle cell anemia.
  • Avoiding reckless lifestyle to avoid trauma and blood loss.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 06, 2023.




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