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2014-03-18 23:45:14
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  1. What regulates ΔALA in hgb synthesis?  Why is this a key enzyme for regulation?
    • erythropoietin
    • ΔALA is the rate limiting step of heme creation, so erythropoeitin can affect the overall rate of heme synthesis
  2. What is the amount of iron in the body?  What is its distribution throughout the body?
    • 3-4g
    • 66% in hemoglobin
    • 30% in marrow, liver, spleen as ferritin and hemsider
    • 3% in myoglobin (not available to body)
    • 1% associated with transferrin and plasma
  3. What are nutritional sources of iron?
    • Green vegetables
    • Cereal
    • Muscle meats
    • Fish
    • Fowl
    • Prunes
    • Yeast
    • Wheat germ
  4. What are the nutritional requirements for iron consumption?
    • Varies with age and sex
    • 10-25mg/day (1-2mg absorbed)
    • *note- intake is only required to meet daily loss by body
  5. Describe the absorption/transport of iron
    • Fe2+ (most) and Fe3+ (some) enter the stomach
    • Fe3+ is reduced to Fe2+ in the presence of HCl
    • Some Fe2+ is lost in feces
    • Some Fe2+ oxidized to Fe3+ and resorbed in the Duodenum and Jejunum (NOT ILEUM) 
    • *note- although iron is transported as Fe3+, it is incorporated to the heme molecule in its Fe2+ form
  6. Describe the daily iron cycle in the body
    • Absorption (1-2mg) must match loss (1-2mg)
    • Tissue Fe (1100mg, 33%) is cycled with Plasma/transport Fe (35mg, 1%)
    • Transported Fe is returned to marrow and incorporated into RBCs (Hgb Fe 2300mg, 66%)
    • RBCs are broken down and Fe is returned to plasma/transport
  7. What are the stages of deficiency in iron deficiency anemia?
    • Stage 1: iron depletion in bone marrow
    • asymptomatic
    • will take a while due to good amount of iron storage
    • Stage 2: iron-deficient erythropoiesis in bone marrow
    • Subclinical
    • occurs after iron stores have been depleted
    • Stage 3: Iron-deficiency anemia visible in peripheral blood
    • most often diagnosed at this stage
    • Can be tested in the lab
  8. What is the etiology of iron deficiency anemia in neonates, children, adults, and others?
    • Neonates: multiple births, iron deficient mother
    • Infants/Children: growth spurts, diet
    • Adults: chronic blood loss, inadequate diet
    • Others: menstrual cycle in women, pregnancy, GI bleeding disorders, repeated blood donations
  9. What are the clinical features of iron deficiency anemia?
    • Pallor, fatigue
    • Headaches, dizziness, difficulty breathing
    • Tachycardia, increase in heart size
    • splenomegaly, hepatomegaly
    • Pica syndrome
    • glossitis (beefy tongue)
    • koilonychia (indented fingernails)
  10. What are the laboratory findings in iron deficiency anemia (RBC count, hgb, hc, indices, blood smear, other various tests)
    • RBC count: 3-5x106/μL
    • Hgb: 4-10g/dL
    • Hct: 20-25%
    • MCV: 60-80fL
    • MCH: 5-25pg
    • MCHC: 20-30%
    • Microcytic, hypochromic blood picture with anisocytosis and poikilocytosis
    • Increased reticulocyte count
    • Increased erythropoietin levels
    • Decreased serum iron
    • Increased TIBC (total iron binding capacity)
    • Decreased iron stores and decreased sideroblasts in bone marrow
  11. Describe the treatment for iron deficiency anemia
    • Dietary changes
    • Supplemental oral iron
    • Iron injections
    • Correct underlying GI abnormalities
    • Blood transfusions (in emergencies)
  12. What is hemochromatosis? Describe it. What age is it usually diagnosed? Why is it important? How can it present itself in patients? Treatment?
    • The opposite of iron deficiency
    • Iron overload in liver, spleen, pancreas
    • Progresses slowly
    • Usually diagnosed between 50-60yrs
    • Must be monitored so that liver is not destroyed (iron builds in liver)
    • Patients sometimes look golden due to destruction of liver and subsequent bile abnormalities
    • No hematological issues except increase in transferrin saturation
    • Often treated with therapeutic phlebotomy
  13. Describe the etiology of sideroblastic anemia
    • Abnormal heme synthesis resulting in abnormal iron deposition near mitochondria
    • *note-most doesn't make it into the mitochondria
    • Inhertited: sex linked or autosomal (rare)
    • Aquired: idiopathic, lead, alcohol, drugs
  14. What are the clinical features of sideroblastic anemia?
    • Weakness
    • Pallor
    • Fatigue
  15. Describe the laboratory findings of sideroblastic anemia? (standard tests, special tests, blood smear, marrow aspiration
    • Decreased RBC and Hgb
    • Variable Hct, MCV, MCH, MCHC
    • Increased serum iron (it is unused)
    • Decreased or normal TIBC
    • Hypochromia, anisocytosis, poikilocytosis, and basophilic stippling on peripheral blood smear
    • Increased iron and ringed sideroblasts in bone marrow
  16. Describe the treatment for sideroblastic anemia?
    • Remove exposure to lead
    • Discontinue alcohol and drug use
  17. What are the various causes of microcytic, hypochromic anemias
    • Disorder of iron metabolism (iron deficiency anemia)
    • Disorder of heme synthesis (sideroblastic anemia)
    • Disorders of globin protein synthesis (thalassemia)