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HelpTest Code FRAG Osmotic Fragility, Erythrocytes
Reporting Name
Osmotic Fragility, RBCUseful For
Evaluating suspected hereditary spherocytosis-associated hemolytic anemia
Confirming or detecting mild spherocytosis
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FRAGO | Osmotic Fragility | No | Yes |
| SCTRL | Shipping Control Vial | No | Yes |
Method Name
Osmotic Lysis
Performing Laboratory
Mayo Clinic Laboratories in Rochester
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 is required.
Specimen Required
Both a whole blood EDTA specimen and a shipping control specimen are required. The shipping control specimen is used to evaluate whether a patient result has been compromised by handling conditions such as temperature, motion, or other transportation interferences. Temperature and handling extremes can adversely impact the integrity of the specimen.
Patient:
Specimen Type: Whole blood
Container/Tube: Lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions:
1. Refrigerate specimen immediately after collection.
2. Send whole blood specimen in original tube. Do not aliquot.
3. Rubber band patient specimen and control vial together.
Normal Shipping Control:
Specimen Type: Whole blood
Container/Tube: Lavender top (EDTA)
Specimen Volume: 4 mL
Collection Instructions:
1. Collect a shipping control specimen from a normal (healthy), unrelated, nonsmoking person at the same time as the patient.
2. Clearly hand write “normal control†on the outermost label.
3. Refrigerate specimen immediately after collection.
4. Send control specimen in original tube. Do not aliquot.
5. Rubber band patient specimen and control vial together. The control and patient specimen must be handled in the same manner from specimen collection to receipt in the testing laboratory.
Specimen Minimum Volume
Patient whole blood, shipping control: 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 |
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
NaCl = sodium chloride
Reference values have not been established for patients who are younger than 12 months of age.
Day(s) Performed
Monday through Saturday
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 |
Clinical Information
Spherocytes are osmotically fragile cells that rupture more easily in a hypotonic solution than do normal red blood cells . Because they have a low surface area:volume ratio, they lyse at a higher osmolarity than do normal discocytes (ie, RBC). 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 a 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.
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 red blood cells (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 canceled if the patient specimen and shipping control are both abnormal.
Method Description
Specimens for erythrocyte osmotic fragility tests are anticoagulated with EDTA. Osmotic lysis is performed using sodium chloride solution, 0.5 g/dL. An incubated fragility test is performed following 24-hour incubation at 37° C at the following sodium chloride 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; King MJ, Zanella A: Hereditary red cell membrane disorders and laboratory diagnostic testing. Int J Lab Hematol. 2013 Jun;35(3):237-243)