Osmotic Fragility Test – RBC Fragility Test – HM042
🩸 Hematology & AnemiaReport: Next day Evening
Sample Type: Blood (Heparinized)
Test Code: HM042
The Osmotic Fragility Test (OFT) determines how fragile your Red Blood Cells (RBCs) are. It measures the RBCs' ability to withstand swelling and bursting (hemolysis) when placed in a hypotonic (watery) salt solution.
✔ The primary test to diagnose Hereditary Spherocytosis (a condition where RBCs are round and fragile).
✔ Helps differentiate between different types of hemolytic anemia.
✔ Can also detect Thalassemia (where cells are more resistant to bursting).
✔ Requires a fresh blood sample.
Why Check RBC Fragility?
Normal Red Blood Cells are shaped like biconcave discs (like a donut without the hole). This shape gives them a high surface-area-to-volume ratio, allowing them to be flexible and swell significantly before they burst.
However, in certain genetic conditions like Hereditary Spherocytosis, the RBCs are shaped like spheres (balls). These spherocytes are already stretched tight. When placed in a hypotonic solution (water), they absorb very little fluid before they burst. This is called increased osmotic fragility.
Conversely, in conditions like Thalassemia or Iron Deficiency Anemia, the cells are flat (target cells). These cells can absorb a lot of fluid without bursting, showing decreased osmotic fragility.
When is this Test Ordered?
A doctor (hematologist) will order this test if a patient (often a child) presents with signs of hemolytic anemia, such as:
- Jaundice (yellowing of skin/eyes)
- Splenomegaly (enlarged spleen)
- Pallor and fatigue
- A family history of anemia or gallstones
- Presence of spherocytes on a peripheral blood smear
Frequently Asked Questions (FAQ)
It is primarily used to diagnose Hereditary Spherocytosis. It determines how easily your red blood cells break apart (hemolyze) when exposed to water/salt solutions.
Increased fragility means your red blood cells burst more easily than normal cells. This is the classic sign of Hereditary Spherocytosis.
Decreased fragility means your red blood cells are resistant to bursting. This is often seen in Thalassemia, Iron Deficiency Anemia, or after a splenectomy.
No, fasting is not required for the Osmotic Fragility Test.
A standard blood draw from a vein in your arm is required. The sample is usually collected in a green-top (Heparin) tube to prevent clotting without damaging the cell membranes.