osmotic fragility test
Pronunciation: oz-MOT-ik frah-JIL-ih-tee
Laboratory test measuring red blood cell resistance to hemolysis in hypotonic solutions, used to diagnose spherocytosis.
Full Definition
A specialized laboratory test that measures the susceptibility of red blood cells to hemolysis when exposed to increasingly hypotonic saline solutions. Normal red blood cells can withstand moderate hypotonic stress due to their biconcave shape and membrane flexibility, while spherocytes hemolyze more readily due to their reduced surface area-to-volume ratio. This test is particularly useful for diagnosing hereditary spherocytosis and can be performed both before and after incubation to increase sensitivity.
Usage
Usage note: Often abbreviated as OF test; results may be reported as incubated vs. non-incubated.
In Context
- "The osmotic fragility test was markedly abnormal, confirming suspected hereditary spherocytosis." — Hematology laboratory report
- "Normal osmotic fragility results excluded spherocytosis as the cause of hemolytic anemia." — Diagnostic workup summary