A 38-year-old male presents for evaluation of anemia. He is otherwise well and has no past medical history.
- Is this anemia secondary to reduced red cell production (i.e. bone marrow failure) or destruction?
- What should you rule out with microcytosis?
- What testing would you order next for this patient?
Click for answer:
Diagnosis: hemoglobin SC disease
CBC Clues:
(1) Sickle cells – suggest underlying hemoglobinopathy
(2) Reticulocytosis – suggests appropriate bone marrow response to anemia
(3) Microcytosis –associated with HbSC disease
Q1: Is this anemia secondary to reduced red cell production (i.e. bone marrow failure) or destruction?
Destruction
Q2: What should you rule out with microcytosis?
Iron deficiency
Q3: What testing would you order next for this patient?
Hemoglobin electrophoresis
| Genotype | Disease State |
| HbSS | SCD |
| HbSC | SCD |
| HbSβ+ | SCD |
| HbSβ0 | SCD |
| HbAC | Trait |
| HbAS | Trait |
| HbAA | N/A |
C = hemoglobin C gene
β+/0= beta-thal trait/major
A = wild-type hemoglobin
CBC Pearls
• Hemoglobin electrophoresis is diagnostic for sickle cell disease
• Sickle cell disease features chronic hemolysis with appropriately high reticulocytes
Sickle cell disease is a hemoglobinopathy with various genotypes. Homozygous mutation of the beta-globin chain (HbSS) is most common. This produces abnormal hemoglobin molecules that can polymerize in the presence of low oxygen and stress. This in turn causes “sickling” of red blood cells that leads to hemolysis, thrombosis, and end-organ damage. Sickle cell disease can also result from compound heterozygote genotypes – meaning a sickle cell gene and another hemoglobinopathy. A sickle cell mutation combined with beta-thalassemia is one common example (HbSB0). In this case, our patient is a compound heterozygote for sickle cell and Hemoglobin C mutations, which results in clinical manifestations of sickle cell disease. Sickle cell trait (a single copy of the sickle cell gene, HbS) is usually asymptomatic.