IRON DEFICIENCY ANEMIA

3rd lecture in hematology by Dr.Alaa Fadhil Alwan

IRON DEFICIENCY ANEMIA

Iron deficiency means a deficit in total body iron resulting from a sustained increase in iron requirements over iron supply. Three successive stages of iron defecincy can be distinguished. 1. iron depletion. 2. Iron-deficient erythropoiesis 3.iron-deficiency anemia

Epidemiology

Iron deficiency is the most common cause of anemia worldwide, occurs especially in toddlers, adolescent girls, women of childbearing age. Without iron supplementation, most women will become iron deficient during pregnancy. Globally, 30% to 70% of the populations in developing countries are iron deficient, with the highest prevalence among persons who have diets low in bioavailable iron, or who suffer from chronic gastrointestinal blood loss as a result of helminthic infection, or both.

Etiology and Pathogenesis

Iron requirement for an individual includes not only the iron needed to replenish physiologic losses and meet the demands of growth and pregnancy but also any additional amounts needed to replace pathologic losses. Physiologic iron losses generally are restricted to the small amounts of iron contained in the urine, bile, and sweat; shedding of iron-containing cells from the intestine, urinary tract, and skin; occult gastrointestinal blood loss; and, in women, blood losses during menstruation and pregnancy. In normal men, the daily basal iron loss is slightly less than 1.0 mg/day. In normal menstruating women, the daily basal iron loss is approximately 1.5 mg/day.
Causes of Iron Deficiency
1. Decreased Iron Intake e.g inadequate dietary iron
2. Decreased Iron Absorption e.g Achlorhydria, Gastric resection, Celiac disease (gluten-sensitive enteropathy), Pica
3. Increased Iron Loss
a. Gastrointestinal blood loss:
Neoplasms
Erosive gastritis due to nonsteroidal anti-inflammatory drugs
Peptic ulcer disease
Erosive esophagitis
Inflammatory bowel disease (Crohns disease, ulcerative colitis)
Diverticular disease
Hemorrhoids
Meckels diverticulum
Infections: hookworm, schistosomiasis
b. Excessive menstrual blood flow
c. Frequent blood donation
d. Hemoglobinuria: paroxysmal nocturnal hemoglobinuria, malfunctioning artificial heart valve, Hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome), Hemodialysis, Idiopathic pulmonary hemosiderosis.
4. Increased Iron Requirements: e.g Infancy, Pregnancy, Lactation


Clinical Presentation
In general, the symptoms of iron deficiency anemia are those of anemia of any cause: fatigue, dyspnea on exertion, and dizziness. There are a few signs and symptoms that are relatively unique to iron deficiency anemia, including koilonychia spoon fingernails, glossitis (atrophy of the papillae of the tongue, with burning or soreness), ulcerations or fissures at the corners of the mouth (angular stomatitis), and dysphagia due to esophageal webs or strictures. The combination of dysphagia, angular stomatitis, and hypochromic anemia has been called the Plummer-Vinson or Paterson-Kelly syndrome. These extreme signs of iron deficiency are now uncommon. Pica is the habitual consumption of unusual substances. It can be both a manifestation and a cause of iron deficiency. Specific examples of pica include geophagia (consumption of earth or clay), pagophagia (ice), and amylophagia (laundry starch). Food pica is the compulsive eating of one kind of food, often crunchy foods such as celery, potato chips, carrots, or raw potatoes. In most cases, pica is a symptom of iron deficiency and disappears when the iron deficiency is relieved.
In koilonychia, the fingernails are thin, friable, and brittle, and the distal half of the nail is a concave or spoon shape resulting from impaired nail bed epithelial growth. This condition is considered virtually pathognomonic of iron deficiency but occurs in a small minority of patients. Blue sclerae, a condition in which the sclerae have a definite or striking bluish hue, were recognized in 1908 by Osler as being associated with iron deficiency and have been reported to be a highly specific and sensitive indicator of iron deficiency.

Laboratory Evaluation

A full blood count and film should be taken. These will confirm the anemia; recognizing the indices of iron deficiency is usually straightforward (reduced hemoglobin concentration, reduced mean cell volume, reduced mean cell hemoglobin, reduced mean cell hemoglobin concentration). Some modern analysers will determine the percentage of hypochromic red cells, which may be high before the anemia develops (it is worth noting that a reduction in hemoglobin concentration is a late feature of iron deficiency). The blood film shows microcytic hypochromic red cells. Hypochromic anemia occurs in other disorders, such as anemia of chronic disorders and Sideroblastic anemias and in globin synthesis disorders, such as thalassemia.
To help to differentiate the type, further hematinic assays may be necessary. Difficulties in diagnosis arise when more than one type of anemia is presentfor example, iron deficiency and folate deficiency in malabsorption, in a population where thalassemia is present, or in pregnancy, when the interpretation of red cell indices may be difficult.
Hematinic assays will demonstrate reduced serum ferritin concentration in straightforward iron deficiency. As an acute phase protein, however, the serum ferritin concentration may be normal or even raised in inflammatory or malignant disease. A prime example of this is found in rheumatoid disease, in which active disease may result in a spuriously raised serum ferritin concentration masking an underlying iron deficiency caused by gastrointestinal bleeding after non-steroidal analgesic treatment

Investigations in iron deficiency anemia

Full blood count and blood film examination
Hematinic assays (serum ferritin, s.iron, s TIBC, Transferrin saturation)
Urea and electrolytes, liver function tests
Fibreoptic and/or barium studies of gastrointestinal tract
Pelvic ultrasound (females, if indicated

ACDFe def.ACD + Fe defSerum ironLow Low-Very low (<15 mcg/dL)LowTIBCLow - normalHigh NormalTransferrin saturationLowLow -Very low (<10%)LowFerritinNormal highLow - Very low (<15 ng/mL)Low - normal

Therapy

Oral iron is the treatment of choice for almost all patients because of its effectiveness, safety, and economy and should always be given preference over parenteral iron for initial treatment. Rarely, red cell transfusions are needed to prevent cardiac or cerebral ischemia in patients with severe anemia. The most common side effects are gastrointestinal. The development of either diarrhea or constipation usually can be treated symptomatically. Often, upper gastrointestinal side effects can be managed by administering the iron with or immediately after meals.
Oral Iron Preparations: Ferrous sulfate Tablets
Parenteral iron therapy should be reserved for patient who (a) remains intolerant of oral iron despite repeated modifications in dosage regimen, (b) malabsorbs iron, or (c) has iron needs that cannot be met by oral therapy because of either chronic uncontrollable bleeding or other sources of blood loss, such as hemodialysis, or a coexisting chronic inflammatory state. The most common preparation is iron dextran complex (Imferon), which contains 50 mg of iron per milliliter of solution. It can be administered intramuscularly or intravenously.
Prognosis
The prognosis for iron deficiency itself is excellent, and the response to either oral or parenteral iron also is excellent. Mild reticulocytosis begins within 3 to 5 days, is maximal by days 8 to 10, and then declines. The hemoglobin concentration begins to increase after the first week and usually returns to normal within 6 weeks. Complete recovery from microcytosis may take up to 4 months.