Common variable immunodeficiency (CVID)
Common variable immunodeficiency is the most common symptomatic primary immunodeficiency, a defect in B-cell differentiation causing low immunoglobulins and recurrent sinopulmonary infections, usually diagnosed after puberty. Diagnosis rests on low IgG with low IgA or IgM plus impaired vaccine responses, and treatment is lifelong immunoglobulin replacement with prompt infection management.
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What this article covers
- Overview
Definition: common variable immunodeficiency (CVID) is a primary antibody deficiency caused by defective B-cell differentiation into plasma cells, producing low serum immunoglobulins and impaired antibody responses.
- Epidemiology
Most common clinically significant primary immunodeficiency, with prevalence around 1 in 25,000.
- Risk factors
Genetic predisposition: most cases are sporadic with unknown cause, but familial clustering and monogenic forms occur.
- Pathophysiology
B-cell differentiation defect: B cells fail to mature into antibody-secreting plasma cells, so immunoglobulin production falls.
- Clinical features
Recurrent sinopulmonary infections: pneumonia, sinusitis, bronchitis, and otitis, the presenting hallmark.
- Differential diagnosis
Selective IgA deficiency: low IgA with normal IgG and IgM; may progress to CVID.
- Diagnosis
Establish with the diagnostic criteria for CVID: low serum IgG (at least two standard deviations below normal) together with a low IgA or low IgM, plus a poor or absent response to protein and…
- Management
Start lifelong immunoglobulin replacement first-line: IVIG 400 to 600 mg/kg IV every 3 to 4 weeks (or an equivalent weekly subcutaneous regimen), titrated to a trough IgG level that controls infections, continued indefinitely.
- Complications
Bronchiectasis and chronic lung disease: the leading cause of long-term morbidity.
- Prognosis
Good with immunoglobulin replacement: infection-related mortality falls substantially once replacement begins.
- Prevention
Maintain a protective IgG trough with immunoglobulin replacement dosed to keep the trough above 500 to 800 mg/dL, which controls most infections.
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