Study Points

Iron: Impact on Health and Wellness

Course #34161 - $15 -

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  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.
  1. The body requires iron for the synthesis of

    FUNCTIONS OF IRON IN THE BODY

    The body requires iron for the synthesis of hemoglobin and myoglobin and for the formation of heme and other enzymes involved in electron transfer. Iron is also a cofactor for enzymes in the brain [8,9]. Approximately 60% of the body's iron is found in hemoglobin in circulating erythrocytes; 25% is contained in a mobilizable iron store; and the remaining 15% is bound to myoglobin in muscle tissue [10,11,12].

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  2. Which of the following is a function of iron?

    FUNCTIONS OF IRON IN THE BODY

    Iron also plays a role in dopamine signaling. Iron deficiency is associated with a disturbance in dopamine metabolism, reduced activity of the dopamine transporter, and abnormal activity of dopamine D1 and D2 receptors in the basal ganglia of the brain [12,13]. Dopamine regulates cognition and emotion and the reward and pleasure centers in the brain, and it controls the release of hormones. Dopamine is active in the prefrontal cortex to promote cognitive control of executive functions, such as planning, working, memory, and sustained attention [14].

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  3. Which of the following functions as master regulator of systemic iron homeostasis?

    IRON HOMEOSTASIS

    Hepcidin, a hormone secreted by the liver, functions as master regulator of systemic iron homeostasis by coordinating iron use and storage with acquisition [18]. Ferroportin is an iron transporter expressed in macrophages, duodenal enterocytes, and hepatocytes [19]. Hepcidin acts by binding to ferroportin, causing its internalization and degradation [20,21]. Loss of ferroportin from the cell surface prevents iron entry into plasma, resulting in low transferrin saturation and less iron delivered to developing erythroblasts. Conversely, decreased expression of hepcidin leads to increased cell surface ferroportin and increased iron absorption [18,20]. Disturbances in this process are the basis for many iron-associated disorders, including anemia and iron-overload-related disorders [22,23].

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  4. Which foods are high in heme iron?

    IRON HOMEOSTASIS

    Iron in the diet is either heme or nonheme iron [15,16,24]. Heme iron, derived from hemoglobin and myoglobin of animal food sources (i.e., meat, fish, poultry), is the most easily absorbable form and contributes 10% or more of total absorbed iron. Nonheme iron is derived from plants and iron-fortified foods and is less well absorbed [24].

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  5. Iron absorption is balanced by losses resulting from

    IRON HOMEOSTASIS

    Approximately 2 mg of iron is absorbed daily in the duodenum and jejunum. This is balanced by losses resulting from desquamation of skin, sloughing of intestinal epithelial cells, and blood loss [16]. Losses also occur due to hemorrhage, problems absorbing iron, and other medical conditions (e.g., end-stage renal disease) [25].

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  6. Of the following, the recommended daily allowance (RDA) of iron is highest for

    DIETARY IRON

    RECOMMENDED Daily ALLOWANCES FOR IRON

    AgeMaleFemalePregnancyLactation
    Birth to 6 months0.27 mga0.27 mga
    7 to 12 months11 mg11 mg
    1 to 3 years7 mg7 mg
    4 to 8 years10 mg10 mg
    9 to 13 years8 mg8 mg
    14 to 18 years11 mg15 mg27 mg10 mg
    19 to 50 years8 mg18 mg27 mg9 mg
    51+ years8 mg8 mg
    aFor this age group, adequate intake (a level assumed to ensure nutritional adequacy) is used because evidence is insufficient to develop an RDA.
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  7. Common signs and symptoms of iron-deficiency anemia include all of the following, EXCEPT:

    IRON DEFICIENCY

    Signs of iron-deficiency anemia include koilonychia, cheilosis, pale/sallow skin, and atrophic glossitis [25]. With koilonychia, the nails (usually fingernails) are abnormally thin and may be spoon-shaped or concave [33]. Cheilosis is an abnormal condition of the lips characterized by surface scaling and fissures in the corners of the mouth [34,35]. Pale, sallow skin may be a result of low levels of hemoglobin. With atrophic glossitis, the tongue appears to be smooth and glossy with a red or pink background [36]. Each of these conditions is reversible with correction of the iron deficiency.

    Symptoms of iron-deficiency anemia include [5,14,25,32,37,38,39]:

    • Chest pain, irregular heartbeat (sign of a more serious deficiency)

    • Fatigue

    • Cognitive deficits

    • Headache

    • Dizziness

    • Dyspnea

    • Pica

    • Restless legs syndrome

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  8. Iron deficiency develops in stages. At which stage does anemia develop?

    IRON DEFICIENCY

    Iron deficiency develops in stages. Stage 1 is characterized by decreased iron stores in bone marrow and serum ferritin levels <20 ng/mL. Iron absorption increases, causing an increase in transferrin level. Erythropoiesis is impaired in stage 2. Although transferrin level is increased, the serum iron level decreases and the transferrin saturation decreases. Anemia develops during stage 3 (with indices that appear normal). Microcytosis and then hypochromia develop in stage 4. In stage 5, iron deficiency affects tissues, with resulting signs and symptoms [51].

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  9. A maternal hemoglobin level less than 6 g/dL has been associated with

    IRON DEFICIENCY

    A hemoglobin level <11 g/dL in the first or third trimester or a hemoglobin level <10.5 g/dL in the second trimester indicates iron-deficiency anemia in the pregnant woman [61]. A maternal hemoglobin level <6 g/dL has been associated with abnormal fetal oxygenation resulting in non-reassuring heart tracings, low amniotic fluid volumes, fetal cerebral vasodilation, and fetal death [62,63].

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  10. Severe iron toxicity is associated with serum iron levels greater than

    IRON TOXICITY

    Normal serum iron levels are 50–120 mcg/dL. Mild-to-moderate systemic iron toxicity is possible when serum iron levels are 350–500 mcg/dL. Hepatotoxicity is usually observed at levels higher than 500 mcg/dL, and levels higher than 800 mcg/dL are associated with severe toxicity. Patients with serum iron levels exceeding 500 mcg/dL require age-appropriate intensive care, including chelation therapy with deferoxamine, but patients with symptoms of toxicity should be treated regardless of serum iron level [82]. Excessive iron has a corrosive effect on the GI tract leading to nausea, vomiting, diarrhea, melena, and hematemesis. Iron overload can damage organs, such as the liver, heart, and pancreas, as well as endocrine glands and joints.

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  • Back to Course Home
  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.