nutritional anemia Flashcards
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
Define reticulocytopenia.
- reticulocytes are new, immature blood cells made in the bone marrow and sent into blood stream.
- reticulocytopenia is a medical term for an abnormal decrease in reticulocytes.
What are characteristics of moderate anemia?
- microcytic and hypochromic
- reticulocytopenic
- ferritin 8
What are symptoms and signs of iron deficiency aneamia?
symptoms:
-fatigue, lethragy, and dizziness
signs :
-pallor of mucous membranes
-bounding pulse
-systolic flow murmurs
-smooth tongue
-koilonychias
What does B12 and folate deficiency lead to/lab findings?
- macrocytic anaemia
- low Hb
- high MCV
- normal MCHC
What can Macrocytic aneamia be characterised into?
- megaloblastic: low retinculocyte count
-vitamin B12/folic acid deficiency
-drug related (inference with B12/FA metabolism) - nonmegaloblastic
- alcoholism ++
- hypothyroidism
-liver disease
myelodysplastic syndromes
-reticulocytosis (hemolysis)
what components of blood is important for final maturation of RBC and for synthesis of DNA?
- vitamin B12 (cobalamin)
- folic acid
both needed for thymidine triphoshpate synthesis.
What is the difference between megablastic vs non megablastic anemia?
- megablastic:
- macrovalocytes and hypersegmented neutrophils
- B12 and folic acid deficiency - non-megablastic anemia:
- myelodysplastic syndrome with several macrocytes.
How is folate deficiency diagnosis made?
- reticulocytes: 20
- folate 0.9 (5-15)
- B12 163 (180-350)
What is folate needed for?
-folate necessary for DNA synthesis: adenosine, guanine and thymidine synthesis.
What are causes of folate deficiency?
- increased demand
- pregnancy
- disseminated cancer
- urinary loss - decreased intake
- poor diet
- chronic alcohol intake
- elderly - decreased absorption
- medication
- coelic
- jejunal resection
What is vitamin B12 needed for?
- essential co-factor for methylation in DNA and cell metabolism
- intracellular conversion to 2 active coenzymes necessary for homeostasis of methylomonic acid (MMA) and homocysteine.
What foods contain vitamin B12 and what are intake recommendations?
food: fish, meat, dairy uk intake: 1.5mcg/day USA intake : 2.4 mvg EU : 1mcg body liver storage : 1-5 mg.
what does vitamin B12 require to be absorbed if made in parietal cells?
- requires the presence of intrinsic factor for absorption in terminal ileum
- IF made in parietal cells in stomach
- transcobalamin II and transcobalamin I transport vitB12 to tissues
What is pernicious anaemia?
- autoimmune disorder caused by Lack of intrinsic factors leading to lack of B12 absorption
- gastric parietal cell antibodies
- IF antibodies
What are clinical consequences of anemia?
- brain = cognition, depression, psychosis
- neurology = myelopathy, sensory changes, ataxia, spasticity (SACDC)
- infertitily
- cardiac cardiomyopathy
- tongue: glossitis, taste impairment
- blood : pancytopenia
What are treatments for deficiency?
treat the underlying cause
- iron - diet, oral, pareteral iron supplementatin, stopping the bleeding
- folic acid - oral supplements
- B12- oral vs intramuscular treatment,
what is microcytic anemia characterised by?
Microcytic anemia is usually characterised by low mean cell volume (average size of RBC)
What are some causes of B12 deficiency
- impaired absorption
- decreased intake
- congenital causes
- increased requirements
- medication
