nutritional anemia Flashcards
(42 cards)
Define anemia
- anemia is a condition in which the number of red blood cells (and consequently their oxygen carrying capacity ) is insufficient to meet the body’s physiological needs
- insufficient oxygen carrying capacity is due to reduced hemoglobin concentration as seen with insufficient RBC
What is hemoglobin?
- iron containing oxygen transport metalloprotein within RBCs
- reduction in hemoglobin = anemia (bc of reduction in oxygen carrying capacity)
What components does red blood cell require for maturation and normal erythropoietin?
- vitamin B12 and folic acid (for DNA synthesis)
- iron (for hemoglobin synthesis)
What makes someone anemic?
- failure of production of RBC: hypo proliferation reticulocytopenic
- inneffictive erythropoiesis
- Decreased survival : blood loss, haemolysis, reticulocytosis
What are 3 categories of mean cell volume and how can we use that to investigate different deficiency?
MCV = average size of RBC
- microcytic : iron deficiency (thalassamia)
- smaller cell, bc not enough Hb , less iron binding - Normocytic : sickle cell (normal size but shape different)
- Macrocytic : B12 deficiency, folate deficiency.
- not enough B12 and folate bc the cell too big and uses it up
Define nutritional anaemias?
- iron deficiency
- vitamin B12 deficiency
- folate deficiency
Why is iron essential?
- for O2 transport
- most abundant trace element in body
- daily requirement for iron for erythropoiesis varies depending on gender and physiological needs
How does daily iron requirement vary?
males and females:
- 7 months to 13 year old same requirements
- females 14-50 have higher iron requirements than males 14-50 y/o
51+ females and males
-lower requirements
-females: higher requirements during pregnancy
What is the distribution of iron in adults?
=>muscle: 300mg =>duodenum : 1-2 mg =>bone marrow: 300 mg =>reticuloendothelial macrophages : 600 mg =>liver : 1000 mg =>plasma transferrin : 3mg => circulating erythrocytes Hb: 1,800 mg
menstruation/other blood loss average : 1-2mg per day iron loss.
What are 2 stable forms of iron?
- ferric (Fe3+)
- ferrous (Fe2+)
What are 2 main storage proteins and where are they found?
- ferritin and haemosiderin
- found in cells of liver, spleen and bone marrow
Why is iron absorption really important?
- iron absorption is the only way iron is regulated.
- iron can’t be excreted only lost during menstruation.
How is iron absorption regulated?
- regulated by GI mucosal cells
- hepcidin in duodenum and proximal jejunum binding to ferroportin receptors on enterocytes.(high levels of hepicidin = less absorption)
What does amount of iron absorbed depend on?
- type ingested
- heme , ferrous (red meat) > than non-red meat
- heme iron makes up 10-20% of dietry iron
- other foods, GI acidity , state of iron storage levels and bone marrow activity affect absorption.
What is the function of hepcidin?
-binds to ferroportin (iron export channel) causing it to be broken down by lysosomes decreasing iron export into blood plasma
What is hepcidin feedback regulated by?
-iron concentrations in plasma and liver and by erythropoietic demand for iron.
How is iron transported?
- iron is transported from enterocytes and then either into plasma or stored as ferritin if excess.
- in plasma: iron attaches to transferrin and then transported to bones marrow where it binds to transferrin receptors on RBC precursors
A state of iron deficiency will see reduced ferritin stores and increased transferrin
What will a state of iron deficiency cause?
-reduced ferritin stores and then increased transferrin
What is the main component you measure in labs iron studies?
- ferritin levels = iron storage
- low ferritin levels indicate low iron levels
- ferritin levels are also high when your unwell so it doesn’t always mean you have high levels of iron - Transferrin saturation = ratio of serum iron and total iron binding capacity
- Transferrin = made by liver, production inversely to Fe stores, vital for iron transport.
- Total iron binding capacity: measurement of the capacity if transferrin to bind iron, indirect measurement of transferrin.
What do results of an iron deficient patient look like?
ferritin = low TF saturation = low Transferrin = high TIBC = high serum iron = low/normal
What does iron lab study show?
- Serum Fe = variable during the day
- Ferritin = primary storage protein and provide reserve, water soluble
- transferrin saturation= ratio of serum iron and total iron binding capacity
- transferrin = made by liver, production inversely proportional to Fe stores. Vital for Fe transport.
- total iron binding capacity = measurement of capacity of transferrin to bind iron it is an indirect measurement of transferrin.
what are causes of iron deficiency?
- not enough in:
- poor diet
- malabsorption
- increased physiological needs - losing too much
- blood loss
- menstruation
- GI tract loss
- paraistes
How do you investigate iron deficiency?
- FBC : Hb, Mean Cell Volume(MCV) , Mean Cell Hb(MCHC), Reticulocyte count.
- iron studies : ferritin , transferrin saturation
- blood films
What are the 2 terms used to describe appearance of blood cells?
- cell size:
- microcytic or macrocytic - cell colour :
- hyperchromic or hypochromic
