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HelpEpic Code LAB848 Osmotic Fragility, Erythrocytes
Additional Codes
Mayo Code: FRAG
Reporting Name
Osmotic Fragility, RBCPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Clinical Information
Spherocytes are osmotically fragile cells that rupture more easily in a hypotonic solution than do normal RBCs. Because they have a low surface area:volume ratio, they lyse at a higher osmolarity than do normal discocyte (RBCs). Cells that have a larger surface area:volume ratio, such as target cells or hypochromic cells are more resistant to lysing. After incubation, an increase in hemolysis is seen in spherocytes. Hereditary spherocytosis typically has greater number of spherocytes than other causes of spherocytosis. Therefore, the degree of lysis is usually more pronounced, but this is not always the case. Some rare disorders can also cause marked fragility and hereditary spherocytosis cases can display moderate fragility.
Useful For
Evaluation of suspected hereditary spherocytosis associated hemolytic anemia
Confirming or detecting mild spherocytosis
Specimen Type
ControlWhole Blood EDTA
Ordering Guidance
Additional Testing Requirements
Shipping Instructions
Specimens must arrive within 72 hours of collection.
Necessary Information
Patient's age and sex are required.
Specimen Required
Both a whole blood EDTA specimen and a control specimen are required as temperature extremes can increase the fragility of the specimen and cause false-positive results.
Patient:
Container/Tube: Lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions:
1. Immediately refrigerate specimen after collection. Refrigerate at 0 to 4° C. Do not freeze. Freezing causes sample lysis, and tests will not be performed on hemolyzed specimens.
2. Send specimen in original tube. Do not aliquot.
3. Rubber band patient specimen and control vial together. Control must accompany the patient sample at all times to ensure the reliability of testing results.
4. Be sure specimen and control are stored and transported together at refrigerated temperature, carefully following proper handling and shipping instructions.
Normal Shipping Control:
Specimen Type: Whole blood
Container/Tube: Lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions:
1. Draw a control specimen from a normal (healthy), unrelated, nonsmoking person at the same time as the patient.
2. Handwrite "normal control" clearly on the outermost label.
3. Immediately refrigerate specimen after collection. Refrigerate at 0 to 4° C. Do not freeze. Freezing causes sample lysis, and tests will not be performed on hemolyzed specimens.
4. Send specimen in original tube. Do not aliquot.
5. Rubber band patient specimen and control vial together. Control must accompany the patient sample at all times to ensure the reliability of testing results.
Specimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Control | Refrigerated | 72 hours | PURPLE OR PINK TOP/EDTA |
| Whole Blood EDTA | Refrigerated | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Clotted blood | Reject |
Day(s) Performed
Monday through Saturday
Reference Values
≥12 months:
0.50 g/dL NaCl (unincubated): 3-53% hemolysis
0.60 g/dL NaCl (incubated): 14-74% hemolysis
0.65 g/dL NaCl (incubated): 4-40% hemolysis
0.75 g/dL NaCl (incubated): 1-11% hemolysis
Reference values have not been established for patients who are <12 months of age.
Interpretation
An interpretive report will be provided.
Cautions
Spherocytosis of any cause will result in increased osmotic fragility. Infrequently, other congenital hemolytic disorders may also be associated with positive results, as in patients with congenital nonspherocytic hemolytic anemia due to RBC enzyme deficiencies.
Patients with an immunohemolytic anemia, or who have recently received a blood transfusion may also have increased RBC lysis.
Resulting Cautions:
Osmotic fragility results will be reported if the shipping control is normal.
If the shipping control is abnormal and the osmotic fragility results on the patient are within normal range, the results will be reported; however, a comment will be added to the report indicating that the shipping control was not entirely satisfactory.
The test will be cancelled if the patient specimen and shipping control are both abnormal.
Clinical Reference
Palek J, Jarolin P: Hereditary spherocytosis. In Hematology. Fourth edition. Edited by WJ Williams, E Beutler, AJ Erslev, MA Lichtman. New York, McGraw-Hill Book Company, 1990, pp 558-569
Method Name
Osmotic Lysis
Method Description
Specimens for erythrocyte osmotic fragility tests are anticoagulated with EDTA. Osmotic lysis is performed using sodium chloride (NaCl) solution, 0.50 g/dL. An incubated fragility test is performed following 24-hour incubation at 37° C at the following NaCl concentrations: 0.60, 0.65, and 0.75 g/dL. Results are reported and interpreted.(Larson CJ, Scheidt R, Fairbanks VF: The osmotic fragility test for hereditary spherocytosis: use of EDTA-anticoagulated blood stored at 4° C for up to 96 hours. Am Soc Clin Pathol Meeting Abstract, 1988; Larson CJ, Scheidt R, Fairbanks VF: The osmotic fragility test for hereditary spherocytosis: objective criteria for test interpretation. Am Soc Clin Pathol Meeting Abstract, 1988)
Report Available
2 to 5 daysTest Classification
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
85557
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| FRAG | Osmotic Fragility, RBC | 98904-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 9064 | Osmotic Fragility, RBC | 34964-7 |
| SCTRL | Shipping Control Vial | 40431-9 |
| 3306 | Osmotic Fragility, 0.50 g/dL NaCl | 23915-2 |
| 3307 | Osmotic Fragility, 0.60 g/dL NaCl | 23918-6 |
| 3308 | Osmotic Fragility, 0.65 g/dL NaCl | 23920-2 |
| 3309 | Osmotic Fragility, 0.75 g/dL NaCl | 23921-0 |
| 3310 | Osmotic Fragility Comment | 59466-3 |
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FRAGO | Osmotic Fragility | No | Yes |
| SCTRL | Shipping Control Vial | No | Yes |
Forms
If not ordering electronically, complete, print, and send a Benign Hematology Test Request (T755) with the specimen.