10.6 Anaemia Part 2 Flashcards
MCV (Mean cell volume) in micro/normo/macrocytic anemia:
Micro: <80fL
Normo: 100fL
Macro: >100fL
fL = femtolitres
TAILS acronym for causes of microcytic anaemia:
- Thalassaemia
- Anaemia of chronic disease
- Iron deficiency
- Lead poisoning
- Sideroblastic anaemia
List some causes of normocytic anaemia
- Anaemia of chronic disease
- Haemolysis
- Mixed B12/folate/iron deficiency
- After acute blood loss
What is a megaloblast. What causes their appearance?
Large, nucleated, erythroblast; delayed maturation of nucleus
Megaloblastic vs non-megaloblastic macrocytic anaemia
Refers to presence/absence of megaloblasts in bone marrow
List some causes of macrocytic anaemia
- B12/folate deficiency
- Alcohol excess
- Liver disease
- Haemolysis (With reticulocytosis)
What is the role of folate in DNA synthesis?
Produces purines (adenine and guanine)
Where is vitamin B12 absorbed, and what is it bound to (+where is that made?)
- Absorbed in ileum
- Must be bound to intrinsic factor
- IF is made in parietal cells of stomach
Where is folate absorbed?
Duodenum and jejunum
True or false: folate plays a role in DNA synthesis during purine production, but B12 has no role in DNA synthesis
- False
- Both are involved
Can we make vitamin B12 within our microbiomes?
- No
- We get if from animals, who obtain it from:
1. Eating bacteria-contaminated food
2. internal production
3. Eating food of animal origin
Are there any vegan/vego food sources of B12?
Nope. None.
List some dietary sources of folate
- Liver
- Leafy greens
- Yeast
- Breads and cereals (fortified)
Can folate withstand cooking well?
No. It is easily destroyed by this.
Nutritional cause of B12 deficiency
Veganism
Nutritional causes of folate deficiency
- Old age
- Institutions
- Poverty
- Famine
List some causes of malabsorption which can cause vitamin B12 deficiency
- Pernicious anaemia (no IF)
- Ileal resection
- Crohn’s disease
- gastrectomy
List one way in which malabsorption can cause folate deficiency
Coeliac disease
List some conditions under which the body’s folate usage increases
- Pregnancy
- Haemolytics anaemia
- Cancer
- Inflammatory diseases
List one type of drug that can cause folate deficiency
Anticonvulsants
What is the mechanism behind pernicious anaemia?
- Autoantibody response attacks stomach
- Leads do destruction of gastric mucosa -> parietal cells destroyed
- Cannot secrete intrinsic factor
List some clinical features of megaloblastic anaemia
- Glossitis
- Angular stomatitis
- Malabosorption symptoms (e.g. weight loss)
- Neuropathy
- Neural tube defect (in pregnant women)
List some broad features of haemolysis of RBCs
- Increased RBC breakdown
- Increased RBC production to compensate
- Damaged red cell on films
Why can haemolytic anaemia cause macrocytosis? Under what circumstances could it be normocytic?
- In response to RBC haemolysis, the body produces more erythrocytes
- This leads to reticulocytosis
- Since reticulocytes are larger than erythrocytes, this increases MCV
- If there is not an adequate marrow response, then we see normocytic anaemia, as no reticulocytes are produced
Explain intrinsic vs extrinsic haemolytic anaemia
Intrinsic: RBCs are destroyed because they are defective
Extrinsic: Destroyed by factors outside the cell itself
List some causes of intrinsic haemolytic anaemia
- Membrane defects
- Metabolic defects (e.g. G6PD)
- Haemoglobin defects (HbS)
List some causes of extrinsic haemolytic anaemia
-Autoimmune/alloimmune (e.g. transfusion) conditions
- Red cell fragmentation syndromes
- Infections
- Burns
Briefly describe glucose 6 phosphate dehydrogenase deficiency and its role in in intrinsic haemolytic anaema
- G6PD is an enzyme required to produce a compound that protects your RBCs from oxidative stress. Therefore, if you don’t have eough, your cells are vulnerable.
- You can get bouts of acute haemolytic anaema when the stress increases, such as in stress or eating fava beans.
- More common in men (favas)
Which gene is mutated in HbS
Beta-globin gene on Chromosome 11 (same as beta thalassaemia)
Does HbS have a lower or higher O2 affinity than HbA?
Lower affinity; lets go more easily
How would we treat a patient who is struggling with an acute issue relating to HbS?
- Supportive care (treat symptom)
- Folic acid
- Exchange transfuion
- Stem cell transplantation
Intravascular vs extravascular haemolytic anaemia
Intra: within vessels
Extra: outside of vessels, such as in the spleen or liver
Describe the two different kinds of autoimmune haemolytic anaemia. What antibody class is involved in each?
- Warm: 37°C (IgG)
- Cold: 4°C (IgM)
List the three kinds of immune-mediated haemolysis
- Autonimmune haemolytic anaemia
- Alloimmune
- Drug-induced
True or false: alcohol and liver disease can cause macrocytic anaemia
True
Does anaemia always have severe symptoms in well-established cases?
- No
- If the onset was slow enough, patients may not notice
List some general symptoms and signs of anaemia
- Fatigue
- Dyspnoea
- Weakness
- Lethargy
- Palpitations
- Cardiac failure
- Pallor mucous membranes
What type of anaemia is indicated by koilinychia
Iron deficiency
What type of anaemia is indicated by jaundice, neuropathy, and angular stomatitis
B12/folate deficiency
What type of anaemia is indicated by petechiae and splenomegaly?
Marrow disorders (too many dodgy cells, spleen enlarges to kill them)
List four investigations for anaemia
- Iron studies
- B12/folate
- markers of haemolysis
- Haemoglobin electrophoresis
What are some indicators of haemolysis?
- LDH
- Bilirubin
- Reticulocyte count
Think of twso haemoglobinopathies than can be detected with Hb electrophoresis
- Sickle cell disease
- Thalassaemia
Is iron deficiency a diagnosis?
- No
- Seek the underlying cause; always consider blood loss
Where is most of the iron stored in the body?
- Liver
- Spleen
- Bone marrow
Identify vulnerable demographics for iron deficiency
- Women (menstruation)
- Pregnant women
- Vegetarians/vegans
- Elderly
- Children
List some iron-rich foods
- Red meats, fish, poultry, eggs
- Legumes
- Grain products (whole-grain)
- Dark, leafy greens and dried fruits
What is the efficiency of iron intake?
14% (7mg in per 1mg absorbed)
Can the body excrete iron?
No
Is divalent or trivalent iron more easily absorbed into the bloodstream?
Divalent; this is why meat iron is easier to absorb than veggie iron
What factors can increase iron absorption?
- Stomach Acid
- Heme form
- High RBC demand
- Meat Factor Protein (MFP)
What factors can decrease iron absorption (with a dietary focus)?
- Low stomach acid (antacid use)
- Dietary fibre (binds to iron)
- Oaxilic acid
- Polyphenols/tannins in tea/coffee
- Excess minerals
What factors can increase the absorption of non-haem iron? How does this give rise to food pairing?
- Meat Factor Protein and vitamin C
- Therefore, pairing plant iron with foods that contain these can maximise absorption
