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.
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.
You might also like to view...
Thick skin, such as that on the soles of the feet, contains how many layers of cells?
A) Six B) Three C) Five D) Four
A 19-year-old male is reported to have taken too many narcotic pain pills that were prescribed for his recent knee surgery. He is extremely sleepy with very shallow breathing. His color is pale and his SpO2 reading is 84%. His body is probably attempting to compensate for his poor level of ventilatory effort by stimulating the respiratory system to increase rate and tidal volume. Normally,
respiratory drive is triggered by changing levels of: A) carbon dioxide. B) pH. C) oxygen. D) glucose.