anemia%20-%20iron-deficiency
ANEMIA - IRON-DEFICIENCY
Anemia is a condition wherein the blood has low levels of red blood cells (RBC), hemoglobin (oxygen-carrying pigment in whole blood) and/or hematocrit (intact RBC in blood) making it insufficient to address the physiologic needs of the body.
Iron-deficiency anemia is the anemia that resulted from inadequate iron supplementation or excessive blood loss.
It is the most common nutritional disorder worldwide and accounts for more than half of anemia cases.
It is prevalent among preschool children and pregnant women.

Definition

  • A condition wherein the blood has low levels of red blood cells (RBC), hemoglobin (oxygen-carrying pigment in whole blood) or hematocrit (intact RBC in the blood) making it insufficient to address the physiologic needs of the body
  • Based on WHO, anemia is defined as having the following hemoglobin concentrations1:
    • Men (≥15 years old): <13 g/dL
    • Women (non-pregnant, ≥15 years old): <12 g/dL
    • Women (pregnant): <11 g/dL in the 1st and 3rd trimesters, declines by 0.5 g/dL in the 2nd trimester
    • Children (12-14 years old): <12 g/dL
    • Children (5-11 years old): <11.5 g/dL
    • Children (6 months - 4 years old): <11 g/dL

1Values for the definition of anemia may vary between countries. Please refer to available guidelines from local health authorities.

Etiology

Causes of Anemia

  • Normocytic anemia when RBC morphology is unremarkable 
    • Blood loss - most common cause
    • Decreased RBC production due to low RBC production or destruction of precursors of RBC within the bone marrow, eg chronic disease
    • Increased RBC destruction, eg hemolysis
  • Macrocytic anemia wherein the RBC is larger than the nucleus of a small lymphocyte on a peripheral smear due to:
    • Megaloblastic causes: Folate and vitamin B12 deficiency, HIV infection, rare inborn errors of metabolism, myelodysplastic syndrome or congenital dyserythropoietic anemia
    • Nonmegaloblastic causes: Marked reticulocytosis, aplastic anemia, abnormal nucleic acid metabolism of erythroid precursors interfering with nucleic acid synthesis, abnormal RBC maturation, other causes such as Down syndrome, alcohol abuse, liver disease and hypothyroidism
  • Microcytic anemia when RBCs appear smaller due to the following pathologic processes:
    • Reduced iron availability/iron-deficiency anemia
    • Acquired disorders of heme synthesis, eg thalassemia 
    • Reduced globin production
    • Rare congenital disorders including sideroblastic anemias, porphyria, and defects of iron absorption transport, utilization and recycling
    • Inflammation or chronic disease
    • Lead poisoning

Signs and Symptoms

  • Primary symptoms include: Dyspnea (exertional or at rest), fatigue, palpitations, headache, faintness or lightheadedness, tinnitus, anorexia, gastrointestinal (GI) disturbances, loss of libido
  • Symptoms of severe anemia include: Lethargy, confusion, tachycardia, retinal hemorrhage that may lead to life-threatening complications such as congestive heart failure, angina, arrhythmia and/or myocardial infarction
  • Symptoms can be due to decreased oxygen delivery to tissues and in patients with acute and marked bleeding, the added insult of hypovolemia
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