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from page 22 reduced amounts of haeme available for adequate erythropoiesis. The reduced mean corpuscular volume( MCV) is generally less than 80( normal range: 80-100fL) with a proportionate reduction in mean haemoglobin concentration less than 27( normal range: 27-32pg). Patients with thalassaemia trait tend to have a disproportionately low MCV relative to the degree of anaemia; nonetheless, it is important to assess the iron stores in these patents if iron deficiency is suspected.
The red cell distribution width( RDW) is also particularly useful in differentiating iron deficiency from other microcytic, hypochromic forms of anaemia as this parameter will become markedly increased with iron deficiency.
In advanced iron deficiency anaemia, the blood film shows
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Figure 5. Normal blood film.
marked red cell anisopoikilocytosis( variable red cell size and shape) with characteristic pencil cells( see figures 5 and 6). Thrombocytosis is frequently noted in
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iron deficiency, especially in the setting of ongoing blood loss. |
Figure 6. Peripheral blood film displaying the morphological characteristics of iron deficiency anaemia, including microcytic and hypochromic red cells, elliptocytes and pencil cells. Thrombocytosis also noted.
Other tests Iron staining of bone marrow particles
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used to be considered the gold standard for diagnosing iron deficiency, but most would agree that this is an inappropriately invasive test to diagnose uncomplicated
iron deficiency. If the diagnosis is elusive, then a therapeutic trial of iron supplementation is usually the preferred alternative to bone marrow biopsy.
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Decreased |
Decreased |
Increased > 15 |
Increased |
Decreased |
< 12-15 % |
Treatment |
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Increased dietary iron intake SIMPLY increasing dietary iron intake for frank iron deficiency, especially with anaemia, is unlikely to be adequate. 1-3 However, educating patients about optimising iron consumption and absorption is important in secondary prevention.
Oral iron supplementation Consider oral iron supplementation as first-line treatment for all causes of uncomplicated cases of iron deficiency. 2, 5, 7, 8 Oral iron replacement is simple, convenient, relatively nontoxic and inexpensive, costing as little as $ 10 per month.
The Gastrointestinal Therapeutic Guidelines recommend a daily oral intake of 100-210mg of elemental iron to treat iron deficiency in adults. 7, 8 There are more than 100 oral iron preparations available over the counter in Australia; not all contain adequate amounts of
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elemental iron to successfully treat iron deficiency anaemia( see table 4). There are minimal differences in the efficacy of oral iron preparations containing adequate amounts of elemental iron.
Take care when prescribing iron to children as high doses can be toxic or even fatal. The Gastrointestinal Therapeutic Guidelines recommend 3-6mg / kg of elemental iron, up to a maximum of 210mg per day, to treat iron deficiency in children. 7, 8 In addition to prescribing oral iron supplementation( see table 4), educate parents of infants and young children about limiting cows milk intake. This is because of its association with cows milk protein-induced colitis and its ability to minimise the absorption of oral iron supplementation compared with water or fruit juice.
For infants older than six months, provide parents with dietary advice
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about foods that are rich in iron or aid in its absorption. Change infants younger than six months who are still solely breastfed or using nonfortified infant formula to iron-fortified infant formula, together with iron supplementation.
Oral iron is best absorbed on an empty stomach( 30-60 minutes prior to, or two hours after, meals). Absorption can be facilitated by ascorbic acid in the form of a glass of orange juice or vitamin C supplementation. However, patients frequently report dyspepsia, heartburn, nausea and other gastrointestinal disturbances, especially when initiating treatment with higher elemental iron preparations. Reassure patients that most of these symptoms ease with time or can be minimised by taking the iron supplements with food, or at night time, or by dividing the doses throughout the day
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or by using sustained-release preparations.
However, if this still proves unsuccessful, then the iron preparation can be changed to one containing less elemental iron or to a liquid preparation( see table 4).
Inform patients about the possibility of developing dark stools, but reassure them that iron supplementation will not cause false-positive faecal occult blood test results. The absorption of oral iron supplements can be reduced by certain antibiotics( including quinolones and tetracyclines), tannins in tea, calcium supplementation, antacids, PPIs, bran and whole grains. 7, 8
Parental iron replacement therapy Although oral iron supplementation is the cornerstone of therapy, some conditions warrant parenteral iron replacement. Indications for
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parental iron include failure of an adequate trial of oral iron supplementation, proximal small bowel malabsorption or resection, severe and persistent gastrointestinal or menstrual blood loss that cannot be compensated with oral iron supplementation, and chronic renal failure patients receiving erythropoietinstimulating agents. 2, 4, 7, 8
Oral iron should not be given concomitantly with parenteral iron, as the absorption of oral iron is reduced following parental iron. Oral iron therapy should not( re) commence for at least one week after an iron infusion. 9, 10 Parenteral iron should be given intravenously( intramuscular iron injections are poorly absorbed) as the iron must first be taken up by the reticuloendothelial system, rather than directly delivered into the circulation. Furthermore, intramuscular iron injections are painful, cause permanent
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