From the Guidelines
Common Variable Immunodeficiency (CVID) diagnostic tests include measuring levels of various immunoglobulin isotypes (IgG, IgA, IgM, and possibly IgG subclasses) in serum, as well as a measure of function or specific antibody production, which should include both protein and polysaccharide antigens.
Key Diagnostic Tests
- Measuring levels of IgG, IgA, and IgM in serum
- Evaluating IgG subclasses
- Assessing specific antibody production in response to:
- Protein antigens
- Polysaccharide antigens
- Flow cytometry analysis of B cells, including:
- B-cell numbers
- Memory B cells
- Isotype switched B cells
Diagnostic Criteria
The diagnosis of CVID should be considered in patients older than 4 years who have:
- Low IgG and IgA levels
- Impaired antibody response
- No genetic lesions or other causes of primary or secondary antibody deficiency 1 A definitive diagnosis of CVID may include a serum IgG level of less than 450 to 500 mg/dL and a serum IgA or IgM level of less than the fifth percentile, with decreased ability to make specific antibodies 1.
Additional Considerations
- Patients with CVID may have normal or reduced B-cell numbers, and about 13% of patients will have less than 3% B cells among peripheral blood lymphocytes 1
- T-cell abnormalities are frequently found in patients with CVID, including reductions in peripheral blood T-cell populations and functional defects 1
- The diagnosis of CVID should be distinguished from other primary immunodeficiencies, such as X-linked agammaglobulinemia (XLA) and selective IgA deficiency (SIGAD) 1
From the Research
Diagnostic Tests for Common Variable Immunodeficiency (CVID)
The diagnostic tests for CVID include:
- Reduced levels of at least two immunoglobulin isotypes: IgG with IgA and/or IgM 2
- Impaired specific antibody response to vaccines 2
- Flow cytometry to demonstrate a disturbed B cell homeostasis with reduced or absent memory B cells and increased CD21(low) B cells and transitional B cell populations 2
- Genetic testing to identify specific genetic mutations that may be associated with CVID 3, 2, 4, 5
- Pulmonary function testing and radiologic studies to evaluate respiratory complications 5
- Laboratory evaluations to monitor disease activity and progression 5
Laboratory Tests
Laboratory tests used to diagnose CVID include:
- Immunoglobulin level tests to measure the levels of IgG, IgA, and IgM in the blood 2, 4
- Antibody response tests to evaluate the body's ability to produce antibodies in response to vaccines or infections 2, 4
- Flow cytometry to analyze the types and numbers of immune cells in the blood 2
- Genetic tests to identify specific genetic mutations associated with CVID 3, 2, 4, 5
Postdiagnostic Evaluation
Postdiagnostic evaluation of CVID includes:
- Continued monitoring of immunoglobulin levels and antibody responses 5
- Regular pulmonary function testing and radiologic studies to evaluate respiratory complications 5
- Laboratory evaluations to monitor disease activity and progression 5
- Genetic analysis to shape precision therapy and monitor the presence and progression of disease in affected tissues 5