Nutritional Anaemia Flashcards
What is anaemia (according to WHO)?
Condition in which the number of RBCs (and their oxygen carrying capacity) is insufficient to meet the body’s physiologic needs
What is haemoglobin?
- Iron containing oxygen transport metalloprotein
- Found within RBCs.
- Reduction in Hb = anaemia
What are the elements found in blood?
- Red blood cells
- Platelets
- White blood cells
- Monocyte
- Lymphocytes
- Eosinophil
- Basophil
- Neutrophil
What are the relative Hb levels and what do you need to look at when interpreting blood results?
- Age and biological gender
- Adolescents reach adult level of Hb
- Women who are not pregnant have lower amounts than men.
- Pregnant women naturally have decreased Hb due to increased circulating volume etc
What should a normal blood film look like?
- A normal blood film will have round RBC with an area of central pallor.
- The central pallor has to be relatively small and the ring should be 1/3 of the diameter.
What does maturation of RBCs need?
- Vitamin B12 and folic acid
- DNA synthesis
- Iron
- Haemoglobin
- Vitamins
- Erythropoeitin
- Healthy bone marrow environment
What are the mechanisms of action of anaemia?
- Failure of haemoglobin production
- Ineffective erythropoeisis
- Decreased survival
What does a failure of haemoglobin production cause?
- Hypoproliferation and reticulocytopenia
What is reticulocytopenia?
- Not enough premature RBCs
What causes ineffective erythropoiesis?
- Enough ingredients but wrong instructions
What causes decreased survival of RBCs?
- Blood loss
- Haemolysis
- Reticulocytosis
What does MCV stand for?
- Mean cell volume
What does MCV mean (not stand for)?
- Average size of RBCs
What does microcytic mean?
- Small MCV
What does normocytic mean?
- Normal MCV
What does macrocytic mean?
- Large MCV
Which anaemias are microcytic?
- Iron deficiency
- Thalassaemia
- Chronic disease anaemia
Which anaemias are normocytic?
- Anaemia chronic disease
- Aplastic
- Chronic renal failure
- Bone marrow infiltration
- Sickle cell disease
Which anaemias are macrocytic?
- B12 deficiency
- Folate deficiency
- Myelodysplasia
- Alcohol induced
- Drug induced
- Liver disease
- Myxoedema
What does reticulocyte count help us with?
Lets us know if bone marrow is working
What does knowing MCV help with?
gives clues on what blood tests to do to predict possible conditions
Which is the most abundant trace element in the body?
Iron - essential for oxygen transport
What is your daily requirement for iron?
- Depends on gender and physiological needs
How much iron is absorbed from the duodenum every day?
1-2mg/day
What is plasma transferrin?
Iron transport protein
Where does most of the iron in the body sit?
- In RBCs, bone marrow and spleen
How do you loose iron naturally?
- Sloughed mucosal cells in the duodenum
or
- menstruation
Where does iron regulation happen?
Absorption stage
What do reticuloendothelial macrophages do?
They:
- ingest senescent red cells
- catabolise haemoglobin to scavenge iron
- load the iron onto transferrin for reuse
What is the structure of Hb and how does this enable it to bind to oxygen?
Hb has 4 haem groups, 4 globin chains able to bind 4 O2
What are the stable form(s) of iron?
Ferric (3+)
Ferrous (2+)
What mechanism is iron absoption regulated by?
Negative feedback of GI mucosal cells and hepcidin
What is hepcidin?
Iron regulatory protein
How does hepcidin work?
Causes the internalisation and degredation of ferroportin, which decreases iron transfer into the blood plasma from the duodenum
What does iron do in plasma?
- Attaches to transferrin and then transported to bone marrow
- Binds to transferrin receptors on RBC precursors
What will iron deficiency do to ferritin/transferrin?
- Reduced ferritin stores
- increased transferrin
What does ferritin do?
Primary storage protein and providing reserve, water soluble
What does the transferrin saturation show you?
Ratio of serum iron and total iron binding capacity - revealing % age of transferrin binding sites that have been occuptied by iron
What is transferrin produced by?
Liver
What is transferrin production inversely proportional to?
Iron stores
What is total iron binding capacity?
- Measurement of the capacity of transferrin to bind iron
- Indirect measurement of iron
Why is the ferritin test so unreliable?
- Ferritin is also involved in immune response, so infection may artificially increase ferritin
With infection, how can you diagnose low ferritin?
- Increased transferrin
What are the causes of iron deficiency?
- Poor diet
- Malabsorption
- Increased physiological needs
- Loosing too much blood
What can cause you to loose too much blood?
- Menstruation
- GIT loss
- Parasites
How can you investigate iron deficiency?
- Full Blood Count (FBC)
- iron studies
- blood film
What are the symptoms of iron deficiency anaemia?
- Fatigue
- lethargy
- Dizziness
- Pale mucus membrane
- Bounding pulse
What are the lab signs of B12 and folate deficiency?
- Low Hb
- high MCV with a normal MCHC
What does megoblastic mean?
- Low reticulocyte count
What causes megaloblastic macrocytic anaemia?
- Vitamin B12/folic acid deficiency
- Drug related
What causes nonmegaloblastic macrocytic anaemia?
- Alcoholism
- Hypothyroidism
- Liver disease
- Myelodysplastic syndromes
- Reticulocytosis
What is a source of vit B12?
- Animal and dairy produce
What is a source of folate?
- Vegetables and liver
What is the adult daily requirement of vit B12?
- 1-2 mcg
What is the adult daily requirement of folate?
- 100-150mcg
Where is vit B12 absorbed?
- Ileum via intrinsic factor
Where is folate absorbed?
- Duodenum and jejunum
What are vit B12 and folate important for?
- RBC maturation
- DNA synthesis
- Thymidine triphosphate synthesis
What are megaloblastic cells characterised by on the peripheral smear?
- Macrovalocytes and hypersegmented neutrophils
What are the causes of folate deficiency?
- Increased demand
- decreased intake
- decreased absorption
What can cause increased folate demand?
- Pregnancy/breastfeeding
- Infancy and growth spurts
- Haemolysis and rapid cell turnover
- Disseminated cancer
- Urinary losses
What can cause decreased intake of folate?
- Poor diet
- Elderly
- Chronic alcohol intake
What can cause decreased folate absorption?
- Medication
- Coeliac
- Jejunal resection
- Tropical sprue
What is vitamin B12 important for?
- Cofactor for methylation in DNA and cell metabolism
Where is vitamin B12 sourced from?
- Fish, meat and dairy
What does vitamin B12 require the presence of to be absorbed into the terminal epithelium?
- Intrinsic factor
Where is intrinsic factor made?
- Parietal stomach cells
What molecules transport vitamin B12 to tissues?
- Transcobalmin II and I
What causes impaired vit B12 absorption?
- Pernicious anaemia
- Gastrectomy or ileal resection
- Zollinger-ellison syndrome
- Parasites
What causes decreased vit B12 intake?
- Malnutrition
- Vegan diet
What are some congenital causes of vitamin B12 deficiency?
- Intrinsic factor receptor deficiency
- Cobalamin mutation CG1 gene
What causes the increased vit B12 requirements?
- Haemolysis
- HIV
- Pregnancy
- Growth spurts
What medication causes vitamin B12 deficiency?
- Alcohol
- NO
- PPI, H2 antagonists
- Metformin
What is pernicious anaemia?
- Autoimmune disorder
What does pernicious anaemia cause?
- Lack of vit B12 absorption or intrinsic factor
Where is pernicious anaemia most prevelant?
- Low income areas
What does a LDH (lactate dehydrogenase) test show?
Breakdown of RBCs. In bone marrow, RBCs are so abnormal they don’t survive.
What are the clinical consequences of pernicious anaemia?
- Brain: cognition, depression, psychosis
- Neurology: sensory changes, spasticity, ataxia
- Infertility
- Cardiac cardiomyopathy
- Tongue: glossitis, taste impairment
- Blood: pancytopenia
