Which of the following is the primary mechanism for anemia in the ...

[B]

Which of the following is the primary mechanism for anemia in the thalassemias?
 
  a. An imbalance in the rate of globin chain synthesis
  b. Impaired iron incorporation into the protoporphyrin ring
  c. Erythroid hypoplasia in the bone marrow
  d. Abnormal amino acid structure of a globin chain

Question 2

Why are infants with b-thalassemia major not ill until approximately 6 months of age?
 
  a. Infants are protected by their high concentration of Hb F.
  b. Infants have less need for hemoglobin because of their small body size.
  c. Infants have less need for hemoglobin because of their smaller lung capacity.
  d. Infants have a high red count and thus higher hemoglobin from a higher than normal concentration of erythropoietin.

[katheyjon]

Answer to Question 1

ANS: A
An imbalance exists in the rate of globin chain synthesis in the thalassemias, and this is the primary mechanism leading to anemia. A build-up of the globin chain is produced in excess, and this causes damage to the red cell. Erythroid hyperplasia is present in the bone marrow (ineffective erythropoiesis).

Answer to Question 2

ANS: A
The b globin chain is decreased to absent in b-thalassemia major; however, a globin chain synthesis is normal. Infants up until approximately 6 months of age have an elevated Hb F that does not require b chains. They become symptomatic after the g-to-b switch.

[B]

TYSM

[smrtceo]

Excellent