HUN3226 Exam 2 Iron Distribution in the body Fe essential to life because it is central in heme which carries oxygen to all living cells Females 2 5 g Males 4g Male 70kg distribution Hemoglobin 2g can vary Storage hemosiderin ferritin 1g can vary Tissue Iron Mg o Myoglobin 130mg o Enzyme iron 8mg o Labile iron pool 80mg Rapid turnover not found in 1 location o Transferrin 3mg Transferring protein of iron Hemoglobin transports oxygen Heme organic ring porphyrin with Fe in the middle o Heme stores oxygen stored in cellular level 4 Hemes make a hemoglobin Myoglobin has same structure as Hemoglobin but only 1 heme enclosed in 1 peptide chain Storage Iron is stored in liver spleen and bone marrow o About 25 30 stored as Ferritin and hemosiderin in the liver Males store 1g iron Females 300mg iron this is a basis for the RDAs Due to menstruation cycle o Ferritin is a ball shaped protein the interior of which can hold about 4500 Fe atoms Small amounts of ferritin are in plasma and reflect storage pools therefore serum ferritin is analyzed for the iron status o Hemosiderin second storage form of iron Major Functions Oxygen transport and storage in hemoglobin and myoglobin structure Part of enzymes that are involved in the electron transport chain and immune system catalytic functions o Krebs cycle enzymes o Enzymes used by plants in photosynthesis o Various plant enzymes used in legumes for nitrogen fixation Notes on Dietary Fe Fe intake in US between 10 30mg day depending on meat consumption 1989 10 15mg day back then for men and women 2001 RDA 8mg for me and older women 18mg for childbearing age women In the last 25 years meat production has decreased o 1000kcal diet 5 7mg day of iron on average o Therefore mixed 2000kcal diet has around 12mg of iron We would need to consume over 3000kcal for women to get the right amount of iron and most Absorption men eat around that amount and have too much iron Iron from exogenous to the foods o From iron pots and pans water sources o Africa Overload of iron from brewing beer in iron Fe in food is in 2 forms heme and nonheme o Heme dietary meat source Myoglobin from muscle Hemoglobin from blood o Non heme form iron salts Non meat sources vegies and grains o To be utilized Fe must be released from various components by HCI from the stomach and proteases from the small intestine o Therefore gastric juices acid and Fe absorption are positively related with low gastric acid Fe absorption is low Fe absorption is most efficient in the upper duodenum although it can occur throughout the small intestine Average person absorbs 5 10 15 of total iron intake this means men 1mg day females 2mg day o Heme is hydrolyzed from the protein globin part and absorbed as such metalloporphyrin o Non heme Fe must be released from food components Fe is primarily oxidized Fe or Ferrin form o Effecting absorption This is poorly soluble form of iron is difficult to absorb In a healthy stomach the acid will reduce this iron Fe to Fe or its reduced state to be absorbed more readily Patients with achlorhydria or insufficient acid or post gastrectomy those taking antacids acid blockers iron will be decreased due to being kept in Ferrin form Reduced from makes it more available To exit the cell it has to oxidized to enable binding to proteins to be able to transport it in the blood Factors increasing Fe absorption All refer to non heme heme is very effected Vit C by far is the strongest factor Organic acids including amino acids citric acid lactic acid Meat fish poultry factor MFP factor refers to beef chicken fish lamb pork and the cysteine content of the meats o also peptides from the digestion of myosin and actin appear to enhance absorption all of the above keep Fe in its ferrous Fe or more readily absorbed form enhanced erythropoiesis making of red blood cells from the bone marrow requires hormone form of kidney o due to blood loss hemolysis hemorrhage hypoxia Fe deficient person will absorb 10 20 Pregnancy particularly in the last half Factors decreasing Fe absorption Rapid transit time Achlorhydria or any medical surgical condition that increases gastric pH Malabsorption syndromes Phytate wheat bran chelate Fe o As little as 5 10mg of phyate can cut iron absorption in half Clay pica Tea 60 reduction due to tannins Coffee 40 reduction due to polyphenols Oxalate spinach Overuse of antacids precipitates Fe o Phosphates and carbonates Iron overload Infection inflammation Calcium might interfere with Fe absorption studies are contradictory o The overall effect of Ca and Fe absorption has a huge effect on women health Iron Transport Transferrin most important transfer protein o Synthesized in live as apotransferrin o As Fe enters blood from intestinal mucosa it is oxidized to Fe by ceraloplasim another circulating protein o Apotransferrin has 2 sites that bine Fe tightly to form transferrin o Transferrin transports iron to various and to the bone marrow cells Have receptors for the synthesis of hemoglobin o Transferrin is normally an 1 3 saturated by Fe Normally transferrin conc In blood is 2 2 3 5 g L Deficiency Fe deficiency is still a serious public health and medical problem that affects many people all over the world It Is manifested as o Weakness overall malaise o Ill health o Substandard performance both physical and mental o Poor ability to maintain body temp in a cold environment o Infants between 6 months and 2 years who are Fe deficient show Decreased responsiveness and activity they are more fatigued more fearful and exhibit other behavioral abnormalities adverse psychometric development o Poor scholastic performance and concentrations in children o Decreased resistance to lead poisoning Fe deficiency increases Pb absorption o Poor maternal stores may be related to Preterm delivery higher maternal mortality o May or may not influence immunity it is not clear Fe deficiency Anemia the final stage of iron deficiency o Therefore w o blood or not enough blood o There is no difference between iron deficiency and iron deficiency anemia o Iron deficiency might have Decrease in Transferrin saturation Serum ferritin But HGB is still NORMAL o If iron deficiency continues to the point that HGB drops ANEMIA occurs Definition of deficiency anemia it s a condition where o The number of RBCs is depressed Expressed as hemocrit conc as blood volume 37 40 for women and men o The size of RBCs is altered Microscopic anemia or small and the color is also altered hypochromic o The
View Full Document
Unlocking...