Tests
1st tests to order
CBC with platelet volume
Test
Perform for all suspected cases. Estimation of platelet size should be requested. May not be reliable postsplenectomy.
Result
thrombocytopenia with small platelet volume
WAS protein (WASp) analysis
Test
Perform for all suspected cases if test is available. If apparently normal but strong clinical suspicion, proceed with WASp gene mutation analysis.
Result
low or absent WASp or WASp of a small molecular size compared with control
WAS protein (WASp) gene mutation analysis
Test
Perform for all suspected cases. This is the definitive test for diagnosis and should be performed even if WASp analysis is suggestive of the diagnosis.
If there are existing genetic test results for the WAS gene, do not order a duplicate test unless there is uncertainty about the existing result, e.g., the result is inconsistent with the patient’s clinical presentation or the test methodology has changed.[19]
Result
sequence analysis for mutation in the WASp gene compared with known normal sequence (detects mutations in about 99% of affected males)
Tests to consider
immunoglobulin levels
Test
Perform for all confirmed cases or if clinically indicated and prior to treatment with immunoglobulin.
Result
extremely variable: often normal IgG; elevated IgA; and, in older patients, low IgM
vaccine responses
Test
Perform for all confirmed cases or if clinically indicated.
Result
may have normal or low responses to protein antigens, more commonly low antibodies to polysaccharide antigens
isohemagglutinins
Test
Perform for all confirmed cases or if clinically indicated.
Result
commonly low
lymphocyte subsets
Test
Perform for all confirmed cases or if clinically indicated.
Result
classically low CD8 T-cell levels, other lymphocyte subsets often normal
T-cell proliferation assays
Test
Perform for all confirmed cases or if clinically indicated.
Result
classically low anti-CD3 stimulation, often normal Pha stimulation in early years
liver function tests
Test
Performed prior to treatment with immunoglobulin.
Result
baseline levels of liver enzymes
polymerase chain reaction analysis for hepatitis C
Test
Performed prior to treatment with immunoglobulin and to document past or present infection; this is particularly important for patients planned for bone marrow transplantation, when infection status is key for treatment planning.
Result
to document lack of infection prior to immunoglobulin (blood product) exposure
polymerase chain reaction tests for adenovirus, Epstein-Barr virus, and cytomegalovirus
Test
Performed prior to treatment with immunoglobulin and to document past or present infection; this is particularly important for patients planned for bone marrow transplantation, when infection status is key for treatment planning.
Result
to document lack of infection prior to immunoglobulin (blood product) exposure
store serum and plasma
Test
Important to have these stored to analyze if the patient develops immunoglobulin-transmitted infection.
Result
in the event that these are required at a later date for specific preimmunoglobulin antibody levels and polymerase chain reaction tests for infection
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