Nutritional anaemia Flashcards
What is anaemia? (3)
- Anaemia is a condition in which the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body’s physiologic needs
- Insufficient oxygen carrying capacity is due to reduced haemoglobin concentration as seen with insufficient RBC
- Anemia is a decrease in number of red blood cells (RBCs) or less than the normal quantity of haemoglobin in the blood
What is Hb?
- Iron containing oxygen transport metalloprotein
* Within RBCs
Can we use Hb levels to diagnose anaemia?
Yes
What does maturation of RBCs require?
• Maturation of red blood cells require
o Vitamin B12 & folic acid; DNA synthesis
o Iron; Haemoglobin synthesis
What are vitamins needed for?
o Cytokines (erythropoeitin) o Healthy bone marrow environment
What are the mechansism of action of anaemia?
• Failure of Production: hypoproliferation (bone marrow can make RBC but doesn’t have right ingredients)
o Reticulocytopenic
• Ineffective Erythropoiesis (cannot make it properly)
• Decreased Survival
o Blood loss, haemolysis, reticulocytosis
Give types of nutrional anaemia
o Iron deficiency
o Vitamin B12 deficiency
o Folate deficiency
What is the function of iron?
What’s our daily requirement and why do women need more?
- Essential for O2 transport
- Most abundant trace element in body
- Daily requirement for iron for erythropoeisis varies depending on gender and physiolgical needs
- Women need more iron due to blood loss from menstruation
What are the daily iron requirements?
- Daily dietary iron requirements differ at various stages of development, between men and women, and between pregnant and nonpregnant women.
- The data reported in this table assume an average dietary iron absorption of 10%.
- Recommended intake assumes 75% of iron is from heme iron sources (meats, seafood). Non-heme iron absorption is lower for those consuming vegetarian diets, for whom iron requirement is approximately 2-fold greater.
How is iron distributed in the body?
- Iron is an essential component of cytochromes, oxygen-binding molecules (i.e., haemoglobin and myoglobin), and many enzymes.
- Dietary iron is absorbed predominantly in the duodenum.
- Fe+++ ions circulate bound to plasma transferrin and accumulate within cells in the form of ferritin. Stored iron can be mobilized for reuse.
- Adult men normally have 35 to 45 mg of iron per kilogram of body weight. Premenopausal women have lower iron stores as a result of their recurrent blood loss through menstruation.
- More than two thirds of the body’s iron content is incorporated into haemoglobin in developing erythroid precursors and mature red cells.
- Most of the remaining body iron is found in hepatocytes and reticuloendothelial macrophages, which serve as storage deposits.
- Reticuloendothelial macrophages ingest senescent red cells, catabolise haemoglobin to scavenge iron, and load the iron onto transferrin for reuse.
- Iron metabolism is unusual in that it is controlled by absorption rather than excretion. Iron is only lost through blood loss or loss of cells as they slough.
- Men and nonmenstruating women lose about 1 mg of iron per day. Menstruating women lose from 0.6 to 2.5 percent more per day.
- An average 60-kg woman might lose an extra 10 mg of iron per menstruation cycle, but the loss could be more than 42 mg per cycle depending on how heavily she menstruates.
- Average values in a 70-kg man. Values in women are lower
- Only lose iron from blood loss- very little excreted
What are the forms of stable iron?
What is it used for?
• >1 stable form of iron:
• Ferric states (3+) and Ferrous states (2+)
• Most iron is in body as circulating Hb
o Hb: 4 haem groups, 4 globin chains able to bind 4 O2
• Remainder as storage and transport proteins
• ferritin and haemosiderin
• Found in cells of liver, spleen and bone marrow
What absorbs iron?
What transports it into the blood?
- Regulated by GI mucosal cells and hepcidin
- Duodenum & proximal jejunum
- Via ferroportin receptors on enterocytes
- Transferred into plasma and binds to transferrin
- Amount absorbed depends on type ingested
- Heme, ferrous (red meat, > than non-heme, ferric forms Heme iron makes up 10-20% of dietary iron
- Other foods, GI acidity, state of iron storage levels and bone marrow activity affect absorption
How is iron-regulated by hepcidin?
How is hepacin regulated?
- the iron-regulatory hormone hepcidin and its receptor and iron channel ferroportin control the dietary absorption, storage, and tissue distribution of iron…
- Hepcidin causes ferroportin internalization and degradation, thereby decreasing iron transfer into blood plasma from the duodenum, from macrophages involved in recycling senescent erythrocytes, and from iron-storing hepatocytes.
- Hepcidin is feedback regulated by iron concentrations in plasma and the liver and by erythropoietic demand for iron.
How is iron transported?
How is iron deff identified
- Iron transported from enterocytes and then either into plasma or if excess iron stored as ferritin
- In plasma: attaches to transferrin
- and then transported to bone marrow binds to transferrin receptors on RBC precursors
- A state of iron deficiency will see reduced ferritin stores and then increased transferrin
Read over Laboratory iron studies
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