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 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 baby 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?
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
Which is the most abundant trace element in the body?
Iron
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?
Sloughed mucosal cells in the duodenum or menstruation
When does iron regulation happen?
Absorption stage
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 and 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 % of transferrin binding sites that have been occuptied by iron
What is transferrin produced by?
Liver
What is transferrin production inversely proportional to?
Fe 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?
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 I and II
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 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
