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.

Diagnosis

  • Anemia diagnosis is confirmed with the presence of low levels of one or more of the major RBC measurements obtained as a part of the complete blood count (CBC): Hemoglobin concentration, hematocrit or RBC count
  • Iron-deficiency anemia diagnosis is obtained by laboratory-confirmed evidence of anemia and low iron stores via measurement of levels of serum ferritin, erythrocyte protoporphyrin, or total iron binding capacity (TIBC, transferrin)
    • Iron deficiency, with or without anemia, may be tested using serum iron and TIBC, serum ferritin, red cell indices, reticulocyte count, reticulocyte hemoglobin concentration, or soluble (serum) transferrin receptor level

History

History and Physical Examination

  • History should focus on possible etiologies and may include queries about diet, GI symptoms, history of pica or pagophagia, signs of blood loss, surgical history and family history of GI malignancy, history of blood donations
  • Patients with iron-deficiency anemia are usually asymptomatic and have limited findings on physical examination, eg pallor of the conjunctivae, skin and nail beds, atrophic glossitis, angular cheilitis, spoon nails, tachycardia, cardiac systolic flow murmur, dry skin and hair, alopecia
  • Further evaluation should be based on risk factors

Laboratory Tests

  • CBC to determine the mean corpuscular volume (MCV) or RBC size
    • A normal MCV in patients with iron-deficiency anemia will require further testing with serum ferritin
  • The serum markers of iron deficiency include low ferritin, low transferrin saturation, low iron, raised total iron-binding capacity, raised red cell zinc protoporphyrin, and increased serum transferrin receptor
  • Serum ferritin level measurement is the most common and easily available test to confirm iron-deficiency anemia
    • Ferritin is an acute phase reactant and reflects iron stores in otherwise healthy adults
    • It can be elevated in patients with chronic inflammation or infection, thus this test should be done in the absence of inflammation
    • It is useful in pregnant women who often have an elevated serum transferrin in the absence of iron deficiency
    • In an anemic adult, a ferritin level of <15 ng/mL is diagnostic of iron deficiency, and levels between 15 to 30 ng/mL are highly suggestive
    • Lower thresholds from 10-12 ng/mL have been used in children
    • This test replaced bone marrow assessment of iron stores which was the gold standard for the diagnosis of iron-deficiency anemia
  • Transferrin level is elevated in patients with iron-deficiency anemia
    • This test can be done if the diagnosis remains unclear
    • It is an indirect measure of erythropoiesis
    • It is unaffected by inflammatory states
    • In pregnant women and taking contraceptives, transferritin is elevated in the absence of iron deficiency
  • Erythrocyte protoporphyrin is a heme precursor and accumulates in the absence of adequate iron stores
  • If other tests are indeterminate and suspicion for iron-deficiency anemia remains, the absence of stainable iron in a bone marrow biopsy is considered the diagnostic standard

Screening

  • It is recommended for asymptomatic pregnant women to have a routine screening for iron-deficiency anemia
    • The defined values consistent with anemia in pregnancy are hemoglobin levels <11 g/dL in the 1st and 3rd trimester or <10.5 g/dL in the 2nd trimester
  • It is also recommended for children >1 year of age to have universal hemoglobin screening and evaluation of risk factors
    • Risk factors include low birth weight, history of prematurity, exposure to lead, exclusive breastfeeding beyond 4 months of life and weaning to whole milk and complementary foods without iron-fortified foods

Evaluation

Endoscopy

  • If gynecological workup in premenopausal women is negative and the patient does not respond to iron therapy, endoscopy should be performed to exclude an occult GI source

Anemia-Iron Deficiency

  • Anemia due to low iron stores in the body
  • Reduced availability of iron is the most important cause of anemia due to impaired erythropoiesis
  • Most common nutritional disorder worldwide and accounts for more than half of anemia cases
  • Most common cause of microcytic anemia although almost half of patients have normocytic erythrocytes
  • High prevalence among children during rapid growth and erythroid expansion especially in premature and low birth weight babies, in toddlers and those in preschool and pregnant women
  • It causes impaired cognitive development in preschool-aged children and diminished work productivity and cognitive and behavioral problems in adults
  • Among pregnant women, it is associated with increased risk of low birth weight, prematurity and maternal morbidity
  • Development and rapidity of progress depend on the individual’s iron stores, which are, in turn, dependent upon age, sex, rate of growth, and the balance between iron absorption and loss
  • Absolute iron deficiency is when the iron stores in the bone marrow and other parts of the monocyte-macrophage system in the liver and spleen are absent, resulting into iron being unavailable for normal or increased rates of erythropoiesis
  • Functional iron deficiency is when there is insufficient availability of iron for incorporation into erythroid precursors despite normal or increased body iron stores
    • Usually due to anemia of inflammation or use of erythropoiesis-stimulating agents

Etiology

  • Blood loss (overt) - most common and important cause
    • Menstrual blood loss - common cause in premenopausal women
    • Gastrointestinal blood loss - common cause in men and postmenopausal women
  • Inadequate iron intake (eg elderly, malnutrition, vegan diet, alcoholism)
  • Iron malabsorption may be due to:
    • Intestinal mucosal disorders (most commonly celiac disease)
    • Impaired gastric acid secretion
    • Gastrectomy and gastric/intestinal bypass procedures
    • H pylori colonization
  • Increase in iron demand (eg rapid growth in children, menstruation, pregnancy, lactation) 
  • Increase in iron loss (eg frequent epistaxis) 
  • Occult bleeding 
  • Congenital iron deficiency
  • Intravascular hemolysis
  • Pulmonary hemosiderosis
  • Response to erythropoietin treatment
  • Chronic diseases and genetic disorders (eg chronic hematuria) 

Signs and Symptoms

  • Commonly asymptomatic
  • Usual symptoms include paleness, weakness, headache, irritability and varying degrees of fatigue, dyspnea and exercise intolerance
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