American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the typical baseline hemoglobin level for persons with Hb SC in sickle cell disease?

1. 6 to 7 g/dL

2. 8 to 10 g/dL

3. 10 to 12 g/dL

4. 4 to 5 g/dL

The correct answer is: 8 to 10 g/dL

Individuals with Hb SC disease typically present with a baseline hemoglobin level that ranges from 8 to 10 g/dL. This condition is a type of sickle cell disease that arises from inheriting one sickle cell gene (Hb S) and one gene for hemoglobin C (Hb C). The combination leads to a phenotype that is less severe compared to homozygous sickle cell disease (Hb SS), allowing for a higher average baseline hemoglobin level. In patients with Hb SC disease, the presence of both Hb S and Hb C results in a moderate degree of hemolysis, which contributes to the lower hemoglobin levels compared to normal individuals but is not as profoundly low as seen in Hb SS disease, where hemoglobin levels can often drop significantly lower than this range. Understanding the expected hemoglobin levels is essential for managing patients with this condition and predicting the associated clinical complications.