Macrocytic anaemia in children is produced by all except –

Morphology of RBC Normal human red blood cells are biconcave discs (diskocytes) with a mean diameter of about 7.5 m. The hemoglobin of red cells is located peripherally, leaving an area of central pallor equal to approximately 30-35% of the diameter of the cells.                                               Cells of normal size and normal hemoglobin content (color) are termed normocytic and normochromic. When red cells diameter is greater than 9 mm, they are referred to as macrocytes. When red cells diameter is less than 6 mm, they are referred to as microcytes. Variation in size of RBCs is known as anisocytosis. Variation in shape of RBCs is known as poikilocytosis. Causes of macrocytosis Causes of megaloblastic anemia : Vitamin B12 deficiency : Decrease intake - Inadequate diet, vegetarianism. Impaired absorption : Intrinsic factor deficiency Pernicious anaemia Gastrectomy Malabsorption states Diffuse intestinal disease eg Lymphoma, systemic sclerosis. Beal resection, ilitis Competitive parasitic uptake eg. fish tape worm infestation. Bacterial over growth in blind loops and diverticula of bowel. Increased requirement: pregnancy, hyperthyroidism, disseminated cancer. Folic acid deficiency : Decreased intake : inadequate diet, alcoholism & infancy Impaired absorption e.g. malabsorption state Intestinal diseases Anticonvulsants, OCP. Increased loss: haemodialysis Increased requirement : Pregnancy, infancy, disseminated cancer & markedly increased haemoptysis. Impaired use : folic acid antagonist. Other causes of megaloblastic anemia Thiamine deficiency                  Pyridoxine deficiency  Hereditary orotic aciduria   Congenital dyserythropoietic anemia      Di-Gueglielrno syndrome    Hypothyroidism