Iron Deficiency Anemia

• Iron deficiency is the most common nutritional disorder worldwide
• Iron deficiency accounts for about half of anemia cases
• Diagnosis is confirmed by low iron stores and below normal hemoglobin

Causes of Iron Deficiency Anemia

• Nutritional deficiency from insufficient iron consumption, such as a poor diet for example
• Faulty or incomplete iron absorption due to achlorhydria, gastric resection, Crohn's disease, or gastrectomy
• Increased iron demand during pregnancy and childhood growth years
• Excessive blood loss, such as from hookworm, acute or chronic hemorrhages, peptic ulcers, stomach carcinoma, or heavy menstruation

Laboratory findings in Iron Deficiency Anemia

• Hemoglobin (Hb) and packed cell volume (PCV) are decreased
• Red cell indices (MCV, MCH, MCHC) are also decreased
• Blood film shows hypochromic, microcytic red cells with anisocytosis
• Reticulocyte count is normal or decreased, but increases with iron treatment
• Platelet count is usually normal, but can increase after acute blood loss
• Serum iron is low, while total iron binding capacity (TIBC) is elevated because TIBC measures transferrin
• Serum ferritin is decreased, because it measures iron stores

Megaloblastic Anemia

• Megaloblastic anemia is caused by inhibited DNA synthesis during red blood cell production
• When DNA synthesis is impaired the cell cycle is blocked, leading to cell growth without division, resulting in macrocytosis
• Red cell DNA synthesis defects are often due to hypovitaminosis, specifically vitamin B12 or folate deficiency

Causes of Megaloblastic Anemia

• Nutritional deficiencies of dietary vitamin B12 or folate
• Malabsorption due to celiac disease, Crohn's disease, or gastric carcinoma
• Increased demand during pregnancy, infancy, and periods of growth
• Defects in DNA synthesis from congenital causes, acute severe pancreatitis, fish tapeworm infestation, or therapy with cytochemical drugs

Laboratory Diagnosis of Megaloblastic Anemia

• Hemoglobin concentration and red blood cell count are below normal
• MCV is high, greater than 100 FL
• Blood film shows macrocytic with ovelocytes
• Leukocytosis and platelets are moderately reduced
• Hyper-segmented neutrophils present in blood film
• Biochemistry may show increased unconjugated bilirubin
• Decreased serum vitamin B12 and folate concentrations

Causes of Macrocytosis (other than Megaloblastic Anemia)

• Pernicious anemia
• Liver disease
• Reticulocytosis
• Alcoholism
• Hypothyroidism