What is the osmotic fragility test result in a patient with thalassemia major most likely to be?

In thalassemia major, the osmotic fragility test is most commonly associated with a decreased result. This decreased osmotic fragility occurs due to the structural integrity of the red blood cells. Individuals with thalassemia major typically have microcytic, hypochromic red blood cells that are less prone to hemolysis in hypotonic saline solutions—this means that they can withstand lower osmotic pressure compared to normal red blood cells.

The pathophysiology behind this involves the alterations in the hemoglobin structure and the membrane composition of the red blood cells in thalassemia major. These alterations enhance the cell's ability to resist osmotic lysis because the cells may be more rigid or have a more effective ability to manage osmotic changes.

When considering the test results and their implications in clinical practice, a decreased osmotic fragility would indicate that the red blood cells are less likely to burst in hypotonic environments, which is characteristic of the changes seen in thalassemia major.