S4 L1 - Intro to anaemia + Vitamin B12 and folate Flashcards
- *Anaemia:**
- Definition
- Signs and symptoms
- Specific signs and symptoms of iron deficiency, B12 deficiency and thalassaemia
- Key clinical feature
Why might anaemia develop:
4 main and explain these
Definition:
A haemoglobin concentration lower than the normal range. Normal range will vary with age, sex and ethnicity so the point at which a patient becomes anaemic depends on these parameters
Signs and symptoms:
Symptoms:
• Shortness of breath • Palpitations • Headaches • Claudication • Angina • Weakness & Lethargy • Confusion
Signs:
• Tachycardia • Systolic flow murmur • Pallor
- *Specific:**
- Iron deficiency: Angular stomatitis, Koilonychia
- B12 deficiency: Glossititis
- Thalassaemia: Abnormal facial bone development
Key clinical feature:
Anaemia in itself is not a diagnosis but a manifestation of an underlying disease state and it is important to establish the cause of the anaemia
Why might anaemia develop?
(pic)
- *Why might anaemia develop?**
- Reduced or dysfunctional erythropoiesis
- *Why might anaemia develop?**
- Defects in haemoglobin synthesis
- *Why might anaemia develop?**
- Abnormal structure and mechanical damage results in haemolytic anaemia
- *Why might anaemia develop?**
- Defects in red cell metabolism
- *Why might anaemia develop?**
- Excessive bleeding
- *Why might anaemia develop?**
- Role of the reticuloendothelial system
- *Why might anaeamia develop?**
- Often multi-factoral
e.g. Mylofirbosis and thalassaemia
- *Evaluation of anaemia**
- Two key features used
- What are reticulocytes, describe them
- What does the reticulocyte count show?
Mind map to evaluate anaemia
- Two key features used:
2 key features can help to work out the cause of an anaemia:
•The rbc size – macrocytic, microcytic, normocytic (big, small, normal)
•The presence or absence of reticulocytosis (has the marrow responded normally?)
- What are reticulocytes, describe them:
• Immature red blood cells (i.e. those which have just been released from the marrow into blood)
• No nucleus & eliminate remaining mitochondria
• Typically compose ~1% of all red blood cells and take ~ 1 day to mature into erythrocytes
- What does the reticulocyte count show?
• Slightly larger than mature red blood cells so an increase in reticulocyte number will increase MCV - Reticulocyte count very useful in evaluating anaemia
• Shows if marrow is capable of responding (would expect anaemia to cause an increase in reticulocyte count if marrow is working normally)
Mind map to evaluate anaemia
(pic)
- *Macrocytic anaemia**
- 3 groups
- Way to remember this
2D’s
3H’s
LAM
- *Folate**
- Source in food
- Store
- Absorption
- Role
- Synthetic form
- *Folate deficiency:**
- Causes
- Symptoms
- When to take folic acid supplements and how much and why
- *- Source in food:** Variety of animal and veg food sources, particularly green leafy veg
- Absorption: mainly duodenum and jejunum
- Store: Liver
- *- Role:** Needed in the synthesis of nucleotide bases required for DNA and RNA synthesis
- Synthetic form: Folic acid
Folate deficiency:
- Causes:
• Dietary deficiency (Poor diet) • Increased requirements: Pregnancy, Increased erythropoiesis e.g. haemolytic anaemia, Severe skin disease (e.g. psoriasis, exfoliative dermatitis) • Absorption: Disease of the duodenum and jejunum (e.g. coeliac disease, Crohn’s disease)
- Symptoms:
• Those related to anaemia • Reduced sense of taste • Diarrhoea • Numbness and tingling in feet and hands • Muscle weakness • Depression
- When to take folic acid supplements and how much and why:
Folic acid (400μg/day) taken before conception & during 1st 12 weeks of pregnancy prevents majority of neural tube defects in babies
- *Vitmain B12
- **Role
- Essential for what normal function and fevelopment
- Source from food
- *Vitamin B12 deficiency:**
- Causes
- One important cause to remember
- Symptoms
- Role:
Essential cofactor for DNA synthesis (due to its role in folate metabolism) • Required for normal erythropoiesis
- Essential for what normal function and fevelopment
• Essential for normal function and development of CNS
- Source from food:
Largely obtained from foods of animal origin (produced by commensal bacteria) • Essential that people on a vegan diet eat foods fortified with vitamin B12 or take a B12 supplement daily (10 µg) or weekly (2mg)
Vitamin B12 deficiency:
- Causes:
• Dietary deficiency (Vegan diet lacking B12 supplementation) • Lack of intrinsic factor (Pernicious anaemia) • Diseases of the ileum (Crohn’s disease, ileal resection, tropical sprue) • Lack of transcobalamin (congenital defect)
- One important cause to remember:
——> Pernicious anaemia: • Decreased or absent Intrinsic factor (IF) causes progressive exhaustion of B12 reserves.
• Autoimmune disease: • 2 types of Antibody (Ab) : • Blocking Ab (more common) blocks binding of B12 to IF. • Binding Ab prevents receptor mediated endocytosis.
- Symptoms:
• Those related to anaemia • Glossitis & mouth ulcers • Diarrhoea • Paraesthesia • Disturbed vision • Irritability
Vitamin B12 absorption
- Neurological conditions caused by B12 deficiency and folate deficiency
- *Subacute combined degeneration of the cord**
- Cause
- Symptoms
Why do B12 and folate deficiency cause megaloblastic anaemia?
- lead to thymidine deficiency
- uracil is incorporated in the absence of thymidine
(see pic for more info)
- *Megaloblastic features in peripheral blood film**
- What do you see
Treatment of Vitamin B12 and folate deficiency
