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IRON DEFICIENCY ANEMIA:
1. TESTS FOR IRON DEFICIENCY ANEMIA
2. IRON DEFICIT
3. IV/IM IRON
4. SIDE EFFECTS OF IV IRON
5. CAUSES OF IRON DEFICIENCY
-------------------------------------------------------------------------- Tests for Iron Deficiency
Ideally the findings that are suggestive of iron deficiency are decreased MCV, low serum iron, high total iron binding capacity (reflective of increased transferrin), low iron saturation and low serum ferritin. However, in the elderly & in the hospitalized patients, these finding are often absent.
1. The MCV can be decreased in 30% of iron-replete patients with anemia of chronic disease. Conversely many iron deficient patients have normal MCV's and as many as 13% have elevated MCV's.
2. Serum iron can be decreased in a variety of states including iron deficiency, inflammation, sleep depravation, and stress. The serum iron level varies tremendously (by as much as 50 ug/dl) from morning to evening and from day to day. The minuscule amount of iron in a multi-vitamin can falsely elevate the serum iron for up to 24 hours.
3. The total iron binding capacity, being a reflection of serum transferrin, is very specific for iron deficiency (near 100%) if it is elevate. Unfortunately being a negative acute phase reactant it has poor sensitivity (less than 30%) and, again, is of little use in the ill patient.
4. The iron saturation (Fe/TIBC x 100) can be decreased below sixteen percent in both anemia of chronic disease and iron deficiency and is of little help in distinguishing between the two.
5. In the normal patient the serum ferritin is directly correlated with iron stores. This relationship holds true even in inflammatory states although the curve is "shifted to the left". That is, for a given level of storage iron in a patient with an inflammatory state the serum ferritin is higher. A ferritin level of greater than 100 ng/ml rules out iron deficiency anemia in any patient. The only exception are in acute hepatitis or liver necrosis (but not chronic liver disease) when the serum ferritin will be massively elevated due to release of liver stores of iron. Ferritin may be falsely elevated also in disseminated TB and Hodgkin's disease. The measurement of the serum ferritin is the most useful and cost effective test of iron stores in the hospitalized patient, the patient with a chronic illness, and the elderly.
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TO CALCULATE TOTAL DOSE NEEDED TO RESTORE HEMOGLOBIN DEFICIT:
Iron to be injected(mg)=(15-HGB[g/dl] X weight (kg) X 3 )
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ADMINISTRATION OF IV IRON:
Iron-dextran complex contains 50 mg Fe per ml solution.
It can be given IV or IM
1. If giving IM:
Administer 0.5 cc test dose
If tolerated, at least 1 hour later give the full dose which should not exceed 2 ml (100 mg)
2. If giving IV:
Administer 0.5 cc test dose
If tolerated, you have two choices
(i)You can give 2 ml of undiluted Iron-dextran complex at a rate of 1 ml / minute. Administer this daily.
(ii)You can give the entire dose diluted in N.S. (5cc:100cc, Fe:NS). Initially the rate should be at 20 drops/minute for 5 minutes and if tolerated then the rate can be increased to 40-60 drops/minute
(iii) You may do as with ii but give the total dose broken into 3 consecutive doses.
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SIDE EFFECTS OF IV IRON
1. Local reations to IM includes pain at the site of injection & skin color changes
2. reactions to IV includes flushing, pain at the IV site if high flow rate, & metallic taste
3. Reactions to both IV & IM include immediate or delayed hypersensitivity reactions
i. Immediate- hypotension, urticaria, headache, malaise, anaphylaxis.
ii. Delayed- fever, lymphadenopathy, arthralgia, myalgia
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CAUSES OF IRON DEFICIENCY
IRON LOSS
1. GI bleed
2. menorrhagia
3. Hemodialysis
4. Hemoglobinuria (PNH, runner's anemia)
5. Alveolar Bleeding (idiopathic, pulm hemosiderosis, Goodpasture's)
6. Frequent blood donations
DECREASED IRON ABSORPTION
1. Post-gastrectomy
2. Celiac disease
3. Hookworm
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