Nutritional Requirement for Erythropoiesis PDF

Nutritional requirement for Erythropoiesis Dr. Mohammed Elshiekh Associate Professor Medical Physiology Session No (3) Faculty Of Medicine Dept. Of Physiology  Objectives : Iron metabloi...

Nutritional requirement for Erythropoiesis Dr. Mohammed Elshiekh Associate Professor Medical Physiology Session No (3) Faculty Of Medicine Dept. Of Physiology  Objectives : Iron metabloism Folic acid Vit B12. Other requirment.  Iron Iron functions: Transport(heamoglobin) and storage(myoglobin) of oxygen Enzymes immunity Iron is an essential component of Hb  The total body contents is about 4 grams distributed:  Distribution of iron in the Body Haemoglobin………………….65% Storage iron…………………..30% myoglobin……………………..3.5% Enzymes……………………….0.5 Transferrin-bound iron………..0.1%  Iron loss from the body is normally very small; in urine,bile and in desquamating cells plus in females:  blood lost monthly(menstrual cycle)  Daily loss in males: 0.6 mg  Daily loss in females: 1.2 mg  The male body needs 0.6 mg and female body 1.2 mg daily  The intestinal iron absorption efficiency is 10%  Dietary requirements for male is 0.6 mg/day  Dietary requirements for female is 1.2 mg/day Iron Metabolism Some people needs more iron: Pregnant women:  To compensate for iron need by fetus during development and lactation o loss in placenta during labor and  Pregnant women should take iron supplement  Growing children girls at puberty  Intestinal iron absorption  Absorption takes place mainly in the upper small intestine [doudenum and upper jejunum]  It must be free and in the reduced form[fe++]  Iron of animal origin is absorbed better than plant iron Intestinal iron absorption  Factors help in absorption:  Hcl of the stomach  Vitamin C Factors inhibit absorption:  Phosphates and phytates(in plants):form insoluble complexes  Some drugs: eg tetracyclin alkalis  Transport of Iron  Iron is transported in the blood mainly bound to transferrin  Transferrin is normally about 30% saturated  Iron is transported to sites needing iron [bone marrow]  Storage Form of Iron A. ferritin Excess iron is stored mainly in the liver as ferritin  Ferritin is soluble and readily gives iron when it is needed B. Haemosidrin  is another storage form of iron It is insoluble Is formed when the iron body contents are abnormally large Deposition of haemosidrin in soft tissues in large amounts causes damage  Iron deficiency Causes anaemia characterized by small,pale red cells  microcytic hypochromic anaemia Causes of iron deficiency:  Inadequate intake  Increased loss:eg A. Intestinal worms B. Ulcer C. Heavy menstruation  Folic acid  A water soluble vitamin  Main dietary sources are green vegetables and liver  Daily requirement is 100-200 microgram  Storage in the body is relatively small  Deficiency develops rapidly in case of inadequate intake  Folic acid is needed for DNA synthesis so essential for cell replication  Normal development of the neural tube  Deficiency leads to production of less number of red cells and larger in size  Macrocytic anaemia[megaloblastic anaemia]  Pregnant mothers need to take folic acid supplements  Vitamin B12 (cyanocobalamin)  Water soluble vitamin  Needed for DNA synthesis  Needed for myelin formation  Dietary sources are animal products only  Requirements is about 1-3 microgm  Body stores[in liver] about 3 mg  So deficiency takes long time to develop if there is no intake  Vitamin B12 absorption  B12 is absorbed from the terminal ileum  B12 must first binds to a factor present in the stomach (intrinsic factor) The intrinsic factor  is secreted by the gastric parietal cells  The intrinsic factor protects the vitamin from being destroyed by the gastrointestinal secretion  Vitamin B12 deficiency  Deficiency is usually not due to nutritional deficiency  The cause of deficiency is commonly due to intrinsic factor deficiency: Pernicious anaemia:  damage of the parietal cells by autoantibodies  Gastrectomy  Diseases of the terminal ileum  B12 deficiency causes:  Macrocytic anaemia [megaloblastic anaemia]  Defect in nervous system myelination  Subacute combined degeneration of the spinal cord