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Test Name:
Sickle Cell Screen (Solubility Test)
- SBMF No:
25169 - Performance Lab Name:
Hematology - Test Mnemonic:
SICKLE SCR - ABN:
Not required - CPT Code:
85660 - LOINC Code:
6864-3 - Also Known As:
Screen for Sickle Cell
Hemoglobin S Screen - Also See:
25170 Sickle Cell with Hemoglobin Evaluation if Indicated - Spec Type:
Whole blood - Spec Container:
Lavender top (EDTA) tube - Pref Vol:
5.0 mL - Min Vol:
1.0 mL - Fasting:
No - Spec Collect:
Routine venipuncture - Spec Process:
Do not centrifuge
Do not remove plasma from cells - Spec Store Transport:
Refrigerated - Spec Stability:
2 weeks refrigerated (2-8°C) - Methodology:
Hemoglobin S Solubility - Use:
Detect presence of sickling hemoglobins - Clinical Significance:
The sickling reaction is based on the relative insolubility of hemoglobin S (HbS). Erythrocytes are lysed by saponin and the released hemoglobin is reduced by sodium dithionite in a phosphate buffer. Its very low solubility and the formation of threadlike liquid crystals characterize reduced HbS, so that in the presence of HbS or non-sickling hemoglobins the system becomes turbid. Other normal hemoglobins lyse with no crystallization and will form a transparent solution. Electrophoretic confirmation is required for conclusive identification in either case. - Reference Range:
Sickle Cell Screen (Solubility Test): Absent
Note: Additional confirmatory testing is recommended for positive screening results - Additional Test Info:
False positive results may occur:
- If the Sickle Cell Reagent is not thoroughly mixed before dispensing into the 12 x 75 mm tubes
- In unstable hemoglobin disorders after splenectomy when large numbers of Heinz bodies are present
- In the presence of hemoglobin C Harlem, hemoglobin C Georgetown and hemoglobin Bart’s
- In blood protein disorders, such as multiple myeloma, due to precipitation of plasma proteins.
When this occurs, the patient’s cells should be washed once with normal saline and centrifuged.
The supernatant is decanted and the cells resuspended to the original volume with normal group compatible plasma.
A test rerun on the washed specimen should yield a correct result.
False negative results may occur if the percentage of HbS is below 10% as in children 6 months of age or younger. - Day Run:
Mon-Sat - Time Run:
8:00 am - Time Reported:
12:00 pm - Test Type:
HEMATOLOGY
