Osmotic Fragility, RBC


Sunquest Code:OSMFRA  
Epic Code:LAB1134Epic Name:FragilityTest Osmotic
Synonyms:RBC Osmotic Fragility; Red Cell Fragility
Methodology:Spectrophotometry
CPT Code:85555
Turnaround Time:Specimens are sent to reference laboratory Mon-Thur; results are reported in 1-5 days.


Collection Instructions

Specimen:Blood and smears
Optimal Volume:5 mL
Minimum\Peds Volume:1 mL
Container:Green (sodium heparin, no gel) (Green (lithium heparin, no gel), Purple (EDTA))
Collection Instructions:Immediately mix specimen 10 times by gentle inversion. Also send 2 smears made from blood being submitted. DO NOT collect after 3:00 pm. Refrigerate within 30 minutes of collection.
Causes for Rejection:Clotted specimen, hemolyzed specimen, specimens greater than 72 hours old.


Processing and Shipping

Specimen Processing:Do not store. Send whole blood and 2 smears made with blood being submitted. Send Mon-Thurs only.
Shipping Instructions:Ship at refrigerated temperature. Must arrive within 24 hours of collection.
Test Performed at or Referral Lab Lab Sendouts  (ARUP)
Referral Lab number:2002257 (OSM FRG)


Interpretive

Reference Range:Within normal curve limits. A graph will accompany laboratory report.
Use:

Erythrocyte osmotic fragility is most often requested in the work-up of possible cases of hereditary spherocytosis (HS). When spherocytes are suspected on the basis of an elevated mean corpuscular hemoglobin concentration or on examination of a peripheral blood smear, the osmotic fragility test may be used to confirm the presence of spherocytes. The test does not distinguish between spherocytes in HS and in acquired autoimmune hemolytic anemia; the test only indicates that a proportion of the red cells have decreased surface-to-volume ratios and are more susceptible to lysis in hypo-osmotic solutions. HS patients who are experiencing significant elevations in reticulocytes may not fall outside of the normal range. Cells with increased surface-to-volume ratios, such as occur in thalassemias and iron deficiency, may show decreased osmotic fragility.

 

For patients with acute hemolysis, a normal red blood cell osmotic fragility test result cannot exclude an osmotic fragility abnormality since the osmotically labile cells may be hemolyzed and not present. Testing during a state of prolonged homeostasis with stable hematocrit is recommended.

 



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