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EPIC CODE: SDEX Sickle Solubility, Blood

Reporting Name

Sickle Solubility, B

Useful For

Screening for presence or absence of hemoglobin (Hb) S (sickle cell disease)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Whole Blood EDTA

Ordering Guidance

This is a screening test only. For quantification of hemoglobin S, order HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood.

Necessary Information

1. Patient's age is required.

2. Include recent transfusion information.

Specimen Required


Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD solution B), green top (heparin)

Specimen Volume: 1 mL

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated 14 days

Reference Values


Day(s) Performed

Monday through Friday

Test 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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
SDEX Sickle Solubility, B 6864-3


Result ID Test Result Name Result LOINC Value
9180 Sickle Solubility, B 6864-3

Clinical Information

Homozygous hemoglobin (Hb) S (sickle cell disease) is a serious chronic hemolytic anemia most commonly found in those of African or Middle Eastern descent.


Hb S is freely soluble when fully oxygenated; when oxygen is removed, polymerization of the abnormal hemoglobin occurs, forming tactoids that are rigid and deformed cells. This leads to sickling of the cells, hemolysis, and many other complications.


Heterozygous Hb S (sickle cell trait) is the most common hemoglobinopathy in the United States. This condition is present in about 8% of African Americans. Usually, Hb S trait exhibits no clinical or hematological effects. A small fraction of people with sickle cell trait have recurrent hematuria.


A positive result should be followed by a complete hemoglobin (Hb) evaluation (HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood) to confirm the presence and concentration of Hb S.


A positive test is presumptive evidence for hemoglobin (Hb) S (sickle cell disease). However, rare sickling Hbs such as Hb C-Harlem (C-Georgetown) and Hb I will also produce a positive result.


This test only detects the presence of Hb S. It cannot differentiate sickle cell trait (heterozygous Hb S) from sickle cell disease (homozygous Hb S), or Hb S in combination with other abnormalities (eg, S/C, S/D, S/G, S/E, S/beta-thalassemia, S/O-Arab, S/New York, and C-Georgetown trait).


The use of packed red blood cells (RBC) instead of whole blood significantly reduces false negatives due to anemia and false positives due to hypergammaglobulinemia (eg, multiple myeloma).


False positives can occur due to large numbers of nucleated RBC.


False negatives can occur due to an insufficient quantity of Hb S due to age (neonates) or transfusion. Hb S concentrations 15% to 20% or less may give a negative result.

Clinical Reference

1. Fairbanks VF: Laboratory methods and case studies. In: Decker BC, ed. Hemoglobinopathies and Thalassemias. Thieme-Stratton Inc; 1980: 105-107

2. Sauntharajah Y, Vichinsky EP: Sickle cell disease: Clinical features and management. In Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Elsevier; 2018:584-607

Method Description

Hemoglobin S reduced by dithionite is insoluble in concentrated inorganic buffers, and thus, the solution is so turbid that newsprint cannot be read through a tube containing the hemolysate and reagents.(Fairbanks VF, Klee GG: Biochemical aspects of hematology. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders Company; 1999: 1678-1679; Greene DN, Vaughn CP, Crews BO, Agarwal AM: Advances in the detection of hemoglobinopathies. Clinica Chimica Acta. 2015; 439:50-57)

Report Available

1 to 4 days

Specimen Retention Time

7 days

Reject Due To

Gross hemolysis Reject

NY State Approved


Method Name

Hemoglobin S Solubility


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