Nutritional Factors Affecting Erythropoiesis

Question 1

How does folate deficiency affect erythrocyte morphology?

Answer 1

1. Folate is converted to tetrahydrofolate (THF) through a series of reactions involving the enzyme dihydrofolate reductase (DHFR)
2. DHFR is converted to 3 functional forms: N5 methyl THF; N5, N10 methylene THF; N10 formyl THF
3. N5, N10 methylene THF transfers one C unit in the reaction that produces thymidine monophosphate from uridine monophosphante
4. N10 formyl THF is involved in purine synthesis, thymidine & purine is essential for DNA synthesis
5. Erythropoeisis is the process of producing RBCs; occurs in bone marrow; begins from large pluripotent hematopoietic stem cells
6. Undergoes many rapid cell divisions to form a mature RBC (active DNA synthesis is essential for this)
7. In folate deficiency, DNA synthesis is impaired due to lack of TMP & purines
8. DNA replication & nuclear maturation is impaired so ↓ rate of proliferation of RBCs
9. However, normal maturation of cytoplasm takes place. Causes nuclear/cytoplasmic desynchrony
10. This unbalanced growth & impaired call division gives rise to macrocytic precursors of erythrocytes (megaloblasts)
11. Megaloblasts are recognized as abnormal RBCs & are destroyed by spleen before normal life span is complete
12. This is known as Megaloblastic anemia

Question 2

Tests to evaluate Iron Status in the body

Answer 2

1. Serum ferritin
2. Serum iron
3. Total iron binding capacity (TIBC)

Question 3

Mature RBCs vs. Reticulocytes

Answer 3

1. Mature RBCs have biconcave shape; nuclear material + ribosomes are absent
2. Reticulocytes show polychromasia; are large & has bluish appearance in staining

Question 4

How does polycythemia affect hematocrit value?

Answer 4

1. Polycythemia is the increased Hb conc. in blood above the normal range for an individual’s age & gender
2. Hematocrit level increases because no. of RBCs increases
3. Increases the % vol. of RBCs in blood