Anaemia - Macrocytic Anaemia

Question 1

What are the 2 Types of Macrocytic Anaemia?

Answer 1

1. Megaloblastic (result of impaired DNA synthesis preventing the cell from dividing normally).
2. Normoblastic.

Question 2

Aetiology of Megaloblastic Anaemia (2).

Answer 2

1. Folate Deficiency.
2. B12 Deficiency.

Question 3

Aetiology of B12 Deficiency (4).

Answer 3

1. Insufficient Dietary Intake (Vegan Diet) of B12 or Malnutrition (Alcoholism).
2. Pernicious Anaemia (commonest).
3. Atrophic Gastritis, Post-Gastrectomy, Zollinger-Ellison syndrome.
4. Disorders/Surgery of Terminal Ileum e.g. Crohn’s.

Question 4

Pathophysiology of Pernicious Anaemia (4).

Answer 4

1. Parietal Cells of Stomach produce Intrinsic Factor (a protein essential for absorption of Vitamin B12 in Terminal Ileum).
2. Autoimmune Antibodies form against Parietal Cells (Reduced Production) or Intrinsic Factor (Blockage).
3. No/Reduced Absorption of B12.
4. A small amount is passively absorbed without binding to IF.

Question 5

Risk Factors of Pernicious Anaemia (3).

Answer 5

1. Middle-Old Age Female.
2. Autoimmune Disorders.
3. Blood Group A.

Question 6

Clinical Features of B12 Deficiency (7).

Answer 6

1. (Symmetrical Leg>Arm) Peripheral Neuropathy with Numbness/Paraesthesiae.
2. Loss of Proprioception and Vibration Sense.
3. Visual Changes.
4. Mood or Cognitive Changes.
   * nerve related = myelination of nerves - B12.
5. Mild Jaundice (+ Pallor) = Lemon Tinge.
6. Glossitis = Sore Tongue.
7. Cardiomyopathy and Infertility.

Question 7

Investigations of Pernicious Anaemia (3).

Answer 7

1. Intrinsic Factor Antibody (1st Line).
2. Gastric Parietal Cell Antibody.
3. Blood Film - Hypersegmented Polymorphs.

Question 8

Management of Pernicious Anaemia (3).

Answer 8

1. Dietary Deficiency - Oral Replacement with Cyanocobalamin (unless severe).
2. Absorption Deficiency - 1mg IM Hydroxycobalamin 3x weekly for 2 weeks and then every 3 months.
3. With Folate Deficiency - Treat B12 Deficiency 1st (Subacute Combined Degeneration of the Cord).

Question 9

What does SCDSC present with? (4)

Answer 9

1. Progressive Weakness.
2. Ataxia.
3. Paraesthesia
4. May progress to Spasticity and Paraplegia.

Question 10

What can Pernicious Anaemia increase the risk of?

Answer 10

Gastric cancer.

Question 11

Blood Film of Megaloblastic Anaemia.

Answer 11

Hypersegmented Neutrophils and Macroovalocytes.

Question 12

What is the function of Vitamin B12?

Answer 12

Essential cofactor for methylation in DNA and cell metabolism and intracellular conversion to 2 active coenzymes, necessary for the homeostasis of methylmalonic acid (MMA) and homocysteine.

Question 13

Dietary Intake of Vitamin B12.

Answer 13

Animal Sources e.g. Fish, Meat, Dairy - UK recommendation : 1.5mcg/day.

Question 14

What is the function of Folate?

Answer 14

DNA Base Synthesis (AGT).

Question 15

Where is Folate absorbed?

Answer 15

Jejenum.