Sickle Cell Disease II

Question 1

Explain the relationship between aplastic crisis and parvovirus B19.

Answer 1

In children, an important cause of aplastic crisis is Parvovirus B19, which causes “fifth disease” and infects RBC precursors, arresting their development into mature RBC’s. This infection is usually transient, but patients may require transfusion of RBCs if hemoglobin falls significantly

Question 2

Describe some of the therapies to treat patients with sickle cell disease and the rationale for therapies: folic acid

Answer 2

could be used in response to developmental delays caused by anemia

Question 3

Describe some of the therapies to treat patients with sickle cell disease and the rationale for therapies: penicillin

Answer 3

Sepsis (overwhelming blood infection) due to spleen death is a common cause of death for infants and young children with sickle cell disease, is significantly reduced by the use of prophylactic penicillin and prompt treatment of fever with additional antibiotic therapy

Question 4

Describe some of the therapies to treat patients with sickle cell disease and the rationale for therapies: exchange transfusion

Answer 4

most people don’t require transfusions. But, if there is worsening anemia, transfusion of RBCs may reverse life-threatening process. Transfusion can be simple or exchange (remove pts RBC’s when normal RBCs are given). Transfusions are associated with transmission of infectious agents and antibody formation and iron overload

Question 5

Describe some of the therapies to treat patients with sickle cell disease and the rationale for therapies: hydroxyurea

Answer 5

oral chemotherapy agent that induces production of HbF which interferes with sickle hemoglobin polymerization. Improves anemia, reduces frequency of acute pain crises and reduces mortality.

Question 6

Describe some of the therapies to treat patients with sickle cell disease and the rationale for therapies: bone marrow transplantation

Answer 6

transplantation done with HLA-matched full sibling unaffected by sickle cell disease with a greater than 90% disease free survival. Only 20% of eligible patients have such a donor available.

Question 7

Explain iron chelation therapy, its indications, and its drawbacks

Answer 7

Administer chelating agents to bind up excess iron, indicated for people who receive multiple simple transfusions because excess iron can lead to organ damage (especially liver and heart). The most common chelation agent, deferoxamine, is infused subcutaneously over 8-12 hours, usually in the abdominal area, 5 to 7 times a week. Compliance with this therapy is challenging for some patients

Question 8

Explain how newborn screens can be used to diagnose sickle cell disease.

Answer 8

Virtually all infants born in the United States are screened at birth for hemoglobinopathies, using the blood from a heel stick placed on filter paper, as is done for the PKU and other
sponsored newborn screening tests. The purpose is early identification of sickle cell disease, so that parental education and prophylactic penicillin can be provided to prevent early mortality. However, it is also an opportunity to identify children with other forms of hemoglobinopathies, including B-thalassemia major