CPHON Practice Exam 2025 – Complete Study Resource

The primary characteristic of hereditary spherocytosis is enhanced rigidity of red blood cells. In this condition, the red blood cells are often spherical rather than the typical biconcave disc shape. This altered shape leads to decreased deformability, meaning the red blood cells become more rigid and less able to traverse the microvasculature, particularly in the spleen. As a result of their rigidity and abnormal shape, these cells are more prone to hemolysis, especially under the conditions present in the spleen. This rigidity is a key aspect that contributes to the clinical manifestations of hereditary spherocytosis, including anemia, jaundice, and splenomegaly.

The other choices do not accurately reflect the characteristics of hereditary spherocytosis. For example, there is not an increased production of red blood cells as the body tries to compensate for hemolysis—rather, the lifespan of these cells is reduced due to their premature destruction. Additionally, the red blood cells are typically smaller and not larger than normal, and they do not have a normal lifespan due to the hemolytic nature of the disease.