Anemia

Original Editor - Lucinda Hampton

Top Contributors - Lucinda hampton and Kim Jackson  

What is Anemia

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Anaemia is a condition in which the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body’s physiologic needs. Anemia is not a diagnosis, but a presentation of an underlying condition.

  • Iron deficiency is thought to be the most common cause of anaemia globally, but other nutritional deficiencies (including folate, vitamin B12 and vitamin A), acute and chronic inflammation, parasitic infections, and inherited or acquired disorders that affect haemoglobin synthesis, red blood cell production or red blood cell survival, can all cause anaemia.
  • The prevalence of anaemia is an important health indicator and when it is used with other measurements of iron status the haemoglobin concentration can provide information about the severity of iron deficiency[1][2].
  • Whether or not a patient becomes symptomatic depends on the etiology of anemia, the acuity of onset, and the presence of other comorbidities eg the presence of cardiovascular disease.
  • Most patients experience some symptoms related to anemia when the hemoglobin drops below 7.0 g/dL.
  • Normal Hemoglobin (Hgb)-specific laboratory cut-offs will differ slightly, but in general, the normal ranges are as follows: 13.5 to 18.0 g/dL in men; 12.0 to 15.0 g/dL in women; 11.0 to 16.0 g/dL in children; Varied in pregnancy depending on the trimester, but generally greater than 10.0 g/dL

Erythropoietin (EPO), which is made in the kidney, is the major stimulator of red blood cell (RBC) production.

  • Tissue hypoxia is the major stimulator of EPO production, and levels of EPO are generally inversely proportional to the hemoglobin concentration.
  • Levels of EPO are lower than expected in anemic patients with renal failure.
  • In anemia of chronic disease (AOCD), EPO levels are generally elevated, but not as high as they should be, demonstrating a relative deficiency of EPO.[3]

Epidemiolgy

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Anemia is an extremely common disease affecting up to one-third of the global population. In many cases, it is mild and asymptomatic and requires no management.

The prevalence increases with age and is more common in women of reproductive age, pregnant women, and the elderly.

  • The prevalence is more than 20% of individuals who are older than the age of 85: incidence of anemia 50%-60% in the nursing homes; in the elderly, approximately 33% of patients have a nutritional deficiency as the cause of anemia eg iron, folate or vitamin B12; 33% of patients, there is evidence of renal failure or chronic inflammation.
  • Classically, mild iron-deficiency anemia is seen in women of childbearing age, usually due to poor dietary intake of iron and monthly loss with the menstrual cycles.
  • Other at-risk groups include alcoholics, the homeless population, and those experiencing neglect or abuse.
  • New-onset anemia, especially in those over 55 years of age, needs investigating and should be considered cancer until proven otherwise (especially true in men of any age who present with anemia).
  • Race is also an important determinant of anemia, with the prevalence increasing in the African American[3] population from eg Thalassemia

Symptoms

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Signs and Symptoms

  1. Can be so mild at first may have no symptoms
  2. If condition gets worse common symptoms generally include:
  • Dizziness, lightheadness, or feeling like you are about to pass out
  • Fast or unusual heartbeat
  • Headache
  • Pain, including in your bones, chest, belly, and joints
  • Problems with growth, for children and teens
  • Shortness of breath
  • Skin that’s pale or yellow
  • Cold hands and feet
  • Tiredness or weakness[4]

Types and Causes

There are more than 400 types of anemia, and they’re divided into three groups:

  1. Anemia caused by blood loss
  2. Anemia caused by decreased or faulty red blood cell production
  3. Anemia caused by destruction of red blood cells[4]

7 Anemias Types

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1. Iron Deficiency Anemia

  • Iron deficiency anemia is the most common type of anemia. 
  • Accounts for approximately 50-percent of the diagnosed cases of anemia. 
  • Can result from inadequate iron intake, decreased iron absorption, increased iron demand, or increased iron loss. 
  • Blood tests such as a complete blood count (CBC) and serum ferritin level are useful for the diagnosis of iron deficiency anemia. A CBC can help determine red blood cell size, hematocrit (percentage of blood volume made up by red blood cells), and hemoglobin. Ferritin reflects iron stores and is the most accurate test to diagnose iron deficiency anemia.  All of these blood tests would be decreased in iron deficiency anemia. Iron deficiency anemia is treated with iron supplementation.

2. Thalassemia

  • Thalassemia is a group of inherited blood disorders characterized by the body making an abnormal form of hemoglobin.
  • Results in hemolysis, or the destruction of red blood cells.
  • More common in individuals of Mediterranean, African, and Asian descent.

3.Anemia in older persons

  • Mounting evidence that low hemoglobin levels are a significant marker of physiologic decline.
  • Prevalence increases with age (approx. 50% in chronically ill patients living in nursing homes).
  • Evidence that even mild anemia is associated with increased morbidity and mortality.
  • About one third of persons have anemia secondary to a nutritional deficiency, one third have anemia caused by chronic inflammation or chronic kidney disease, and one third have unexplained anemia.
  • Nutritional anemia is effectively treated with vitamin or iron replacement. Iron deficiency anemia often is caused by gastrointestinal bleeding and requires further investigation in most patients.
  • Anemia of chronic inflammation or chronic kidney disease may respond to treatment of the underlying disease and selective use of erythropoiesis-stimulating agents.[5]

4. Aplastic Anemia

  • Aplastic anemia refers to a deficiency of all types of blood cells (red cells, white cells, and platelets) caused by bone marrow failure. 
  • Rare and serious condition that can develop at any age and can be fatal. 
  • Develops when a person’s bone marrow is injured eg from from radiation and/or chemotherapy treatments, exposure to toxic chemicals, certain medications (antibiotics), autoimmune disorders (lupus and rheumatoid arthritis), and certain viral infections (hepatitis, Epstein-Barr, cytomegalovirus, parvovirus B19, and HIV).

5. Hemolytic Anemia

  • Hemolytic anemia is a disease in which red blood cells are destroyed and removed from the bloodstream before their lifespan is over. 
  • Average lifespan of a red blood cell is 120-days. 
  • Hemolytic anemia can be inherited or acquired. 
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6. Sickle Cell Anemia

  • Sickle cell anemia is an inherited disorder of red blood cells. 
  • People with the disease have inherited two hemoglobin S genes, one from each parent.  The condition is termed hemoglobin SS and leads to sickle cell anemia. 
  • In this disease, red blood cells assume a crescent, or sickle shape.  Under normal circumstances red blood cells are disc shaped. 
  • The sickle shaped red blood cells can slow or block the flow of blood to body tissues and organs leading to attacks of sudden, severe pain (pain crises).

7. Pernicious Anemia

Pernicious anemia is a decrease in red blood cells that occurs when the intestines cannot properly absorb vitamin B12. 

  • The body needs vitamin B12 to make red blood cells. 
  • The intestines cannot properly absorb vitamin B12 due to a deficiency of a special protein called intrinsic factor in the stomach. 
  • The disease is more common in individuals of Celtic (English, Irish, or Scottish) or Scandinavian origin.  In adults, symptoms of pernicious anemia are not seen until after age 30 and the average age at diagnosis is 60. 
  • Can lead to irreversible nerve damage if treatment is not initiated within 6-months of developing symptoms.

Patient Education

  • Patients with nutritional anemia due to iron deficiency should be educated on food which is rich in iron. Foods such as green leafy vegetables, tofu, red meats, raisins, and dates contain a lot of iron. Vitamin C helps to increase dietary iron absorption.
  • Patients must be advised to avoid excess tea or coffee, as these can decrease iron absorption.
  • Patients on oral iron supplementation must be educated that there is an increased risk of constipation and of the risk of passing black tarry stools.
  • Vegan and vegetarian patients, who may be deficient in B12 must be advised to consume food fortified with vitamin B12, such as certain plant and soy products.
  • Patients who had gastric sleeve operations and sleeve gastrectomies are at an increased risk of vitamin B12 and folate deficiency, due to the loss of absorptive surface at the terminal ileum.

Concluding Remarks

  • Healthy food 2.jpg
    Anemia is a condition in which the body lacks enough healthy red blood cells to carry adequate oxygen to your body's tissues.
  • There are many forms of anemia, each with its own cause.
  • Anemia can be temporary or long term, and it can range from mild to severe.
  • Anemia can be a warning sign of serious illness.
  • Treatments for anemia range from taking supplements to undergoing medical procedures.
  • Some types of anemia by eating a healthy, varied diet.

References

  1. WHO anemia Available from:https://www.who.int/vmnis/indicators/haemoglobin.pdf (last accessed 14.7.2020)
  2. MPR Anemia Available from:https://www.empr.com/home/tools/patient-fact-sheets/anemia-patient-information-fact-sheet/ (last accessed 13.7.2020)
  3. 3.0 3.1 Turner J, Parsi M, Badireddy M. Anemia. InStatPearls [Internet] 2020 Apr 12. StatPearls Publishing. Available from:https://www.ncbi.nlm.nih.gov/books/NBK499994/ (last accessed 13.7.2020)
  4. 4.0 4.1 webMD Anemia Available from:https://www.webmd.com/a-to-z-guides/understanding-anemia-basics#1 (last accessed 13.7.2020)
  5. GLANCE A. Anemia in Older Persons. Am Fam Physician. 2010 Sep 1;82(5):480-7.Available from:https://www.aafp.org/afp/2010/0901/p480.html (last accessed 13.7.2020)