Common Variable Immunodeficiency (CVID)
Understanding CVID
Common Variable Immunodeficiency (CVID) is one of the most frequently diagnosed primary immune deficiencies and is characterized by low immunoglobulin levels, resulting in an increased susceptibility to recurring infections. The degree and type of deficiency of immunglobulins and the clinical presentation can vary from patient to patient, thus the use of “variable” in the description. People diagnosed with CVID may present with low immunoglobulin types G and A (IgG and IgA), and others may present with low IgG, IgA, and immunoglobulin type M (IgM). Others may have T-cell defects which may contribute to increased infections, and autoimmune or inflammatory manifestations, granuloma and an increased susceptibility to cancer when compared to the general population. People with CVID have a lack of functional antibodies which is found as part of the diagnostic workup.
Symptoms of CVID
While 20% of patients have symptoms of the disease in childhood, the majority of patients are diagnosed in their 30s or 40s. The usual presenting features of Common Variable Immunodeficiency (CVID) are recurrent infections involving the ears, nasal sinuses, bronchi (breathing tubes) and lungs (respiratory tract). When the lung infections are severe and occur repeatedly, permanent damage with widening and scarring of the bronchial tree, a condition termed bronchiectasis, may develop.
Diagnosing CVID
Common Variable Immunodeficiency (CVID) can be suspected in children or adults who have a history of recurrent bacterial infections involving ears, sinuses, bronchi and lungs. The characteristic laboratory features include low levels of serum immunoglobulins, including IgG, often IgA and sometimes IgM. An additional diagnostic test includes checking whether there is a lack of functional antibodies. Very low or absent antibody levels following administration of specific vaccines will indicate the lack of functional antibodies. Tests include measuring the serum level of antibody against vaccine antigens (tetanus or diphtheria, measles, mumps, or rubella, Haemophilus influenzae type b [Hib] or pneumococcal polysaccharide).
Treating CVID
The treatment of Common Variable Immunodeficiency (CVID) is similar to that of other disorders with low levels of immunoglobulins. In the absence of a significant T-lymphocyte defect or organ damage, immune globulin replacement therapy almost always brings improvement of symptoms. Immune globulin is extracted from a large pool of human plasma and contains all the important antibodies present in the normal population. Immune globulin therapy can be administered into the blood stream intravenously (IVIG) or under the skin subcutaneously (SCIG).
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