Osmotic Fragility, Erythrocytes

Test Code

13072

CPT Codes
85555, 85557<br>Restricted Client Code

Preferred Specimen

1st specimen
4 mL whole blood collected in EDTA (lavender-top) tube, and

2nd specimen (for Control):
4 mL whole blood collected in EDTA (lavender-top) tube

Minimum Volume

2 mL

Instructions

Both a whole blood EDTA specimen and a shipping control specimen are required.

Patient's age is required.
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.

Specimens must arrive within 72 hours of collection.

If not ordering electronically, complete, print, and send a Benign Hematology Test Request (T755) with specimen.

Note: **Specimens cannot be collected at a PSC**

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

Room temperature: Unacceptable
Refrigerated: 72 hours
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Clotted blood

Methodology
Osmotic Lysis

FDA Status
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.

Setup Schedule

Set up: Mon-Sat; Report available: 2-5 days

Reference Range

≥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

Clinical Significance

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: 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.
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Reference
1. Palek J, Jarolin P: Hereditary spherocytosis. In: Williams WJ, Beutler E, Erslev AJ, Lichtman MA, eds. Hematology. 4th ed. Mcgraw-Hill Book Company; 1990:558-569
2. King MJ, Garcon L, Hoyer JD, et al: International Council for Standardization in Haematology. ICSH guidelines for the laboratory diagnosis of nonimmune hereditary red cell membrane disorders. Int J Lab Hematol. 2015 Jun;37 (3):304-325

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.