Iron and B12 Absorption, Anemia PDF

Iron Absorption  Iron Absorption Daily Requirement: 0.6 mg Absorption: upper part of small intestine Storage: in the liver Functions: formation of Hb & myoglobin Requires: Hcl & vitamin C Its deficiency: Microcytic anemia  Iron Absorption 1- Iron absorbed in ferrous st...

Iron Absorption  Iron Absorption Daily Requirement: 0.6 mg Absorption: upper part of small intestine Storage: in the liver Functions: formation of Hb & myoglobin Requires: Hcl & vitamin C Its deficiency: Microcytic anemia  Iron Absorption 1- Iron absorbed in ferrous state while iron in diet is ferric. 2- Reduction of ferric to ferrous occurs by gastric Hcl and ascorbic acid (vitamin C). 3- Iron absorbed mainly in upper part of small intestine (duodenum). 4- Part of iron is delivered to mitochondria. 5- Remaining part is either combined with apoferritin (in intestine) or carried in plasma on transferrin. 6- Iron combined with apoferritin is changed to ferritin which is main storage of iron. 7- Iron transported in blood bound to transferrin to all part of body and stored in liver as ferritin. 8- Deficiency in iron is due to a- Decreased intake b- Decrease absorption c- Chronic blood loss (Piles)  B12 Absorption Daily Requirement: 5μg Absorption: lower part of small intestine (terminal ileum) Storage: in the liver Functions: DNA formation, Cell division, Cell maturation & Formation of myelin sheath Requires: intrinsic factor Its deficiency: Macrocytic anemia  B12 absorption 1- Intrinsic factor secreted by gastric gland (parietal cell). 2- Intrinsic factor combines with vitamin B12 for protection and transport of B12. 3- Vitamin B12 absorbed from lower part of small intestine (ileum). 4- Vitamin B12 enter mucosal cell with intrinsic factor by pinocytosis. 5- Inside cell vitamin B12 set free in order to be absorbed to blood where it bound to transcobalamine II to every part in the body and stored in liver. 6- Deficiency in vitamin B12 may be due to a- Decreased intake (Rare) b- Decrease absorption  ANAEMIAS Are pathological conditions characterized by decreased number of RBCs or its Hb contents. * Classification of anemia: I- Etiological classification (cause): 1- Precursor cell failure: a- Iron deficiency. b- Vitamin B12 deficiency: megaloplastic. c- Anemia of renal disease. d- Anemia of endocrinal disease: pituitary, adrenal and thyroid hormones deficiency. 2- Haemorrhagic anaemia (blood loss): a- Acute blood loss: accidents & haematemesis. b- Chronic blood loss: piles. 3- Hemolytic anemia (RBCs destruction): A- Extra-corpuscular causes (acquired causes): a- Chemicals: as lead poisoning. b- Some diseases as malaria. c- Snake venom. d- Severe trauma. e- Hypersplenism. f- Incompatible transfusion. B- Intracorpuscular causes (congenital causes): a- Abnormal RBCs: spherocytosis. b- Congenital deficiency of G-6-PD enzyme. c- Abnormal Hb: sickle cell anemia. 4- Stem cell failure (Aplastic anaemia): bone marrow damage: a- Irradiation: exposure to gamma rays. b- Drugs as chloramphenicol. c- Chemicals as arsenic. d- Leukemia. e- Chronic bone infections. 5- Nutritional or deficiency anemia. II- Morphological classification (RBCs size): 1- Normocytic normchromic anemia: a- Acute hge. b- Hemolytic anemia. c- B M failure. d- Chronic diseases. 2- Microcytic hypochromic anemia: iron deficiency anemia. 3- Macrocytic anemia: vitamin B12 and folic acid deficiency. * Effects of anemia: 1- Pallor: seen in mucus membrane & nail bed. 2- General ill health: rapid fatigue & dyspnea. 3- Headache, blurred vision & fainting. 4- Tachycardia & big pulse pressure. 5- Specific signs: a- Fe++ deficiency: spooning of he nail. b- Haemolytic anaemia: jaundice. c- Sickle cell anaemia: leg ulcers. d- Megaloblastic: sensory disturbances.  Pernicious anemia autoimmune familial disease elderly & more common in ♀ - It is due to immune reaction against parietal cells causing achlorhydia and & absence of intrinsic factor. - There is degeneration of posterior and lateral column of spinal cord leading to neurological manifestations. Treatment of anemia 1- Treatment of the cause: a- Iron deficiency: iron supplmentation by mouth or injection. b- Pernicious anemia: B12 injection. c- Folic acid deficiency: folic acid. 2- In severe cases: blood transfusion.  Blood Indices These are values obtained by relating Hb, PCV (Ht) & RBCs count to each other. 1- Colour Index (CI): rough indication of Hb content of blood compared to Hb of normal. CI = Hb content (expressed as % of normal) RBCs count (expressed as % of normal) Normally = 0.9-1.1 high in pernicious & low in iron deficiency. 2- MCV = hematocrite x 10 = 90μ3 number of RBCs 3- MCH = Hb / 100 ml blood = 30 pg number of RBCs 4- MCHC = Hb / 100 ml blood = 33% hematocrite