An increased osmotic fragility is typically seen in which type of hemolytic anemia?

An increased osmotic fragility is a hallmark of hereditary spherocytosis, which is a condition characterized by the presence of spherocytes—spherical red blood cells that are less stable and more prone to lysis in hypotonic solutions compared to normal red blood cells. In hereditary spherocytosis, the defect in the red blood cell membrane leads to decreased surface area relative to volume, causing these cells to be rigid and less able to withstand osmotic pressure changes.

When red blood cells are subjected to hypotonic solutions, they swell and undergo hemolysis if their membrane integrity is compromised. The spherocytes' altered membrane composition and shape result in an increased susceptibility to osmotic stress, reflecting in higher osmotic fragility.

In contrast, thalassemia primarily involves defects in hemoglobin synthesis, leading to microcytic anemia but not significantly affecting osmotic fragility. Hemolytic disease of the newborn is associated with immune-mediated destruction of red blood cells but does not present with similar osmotic fragility patterns as hereditary spherocytosis. Sickle cell anemia, while also a hemolytic anemia, is characterized by the polymerization of hemoglobin S under low-oxygen conditions, affecting red cell shape and leading to vaso