Immunoglobulin G Deficiency Workup

Updated: Mar 01, 2017
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Michael A Kaliner, MD  more...
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Workup

Laboratory Studies

Values or all immunoglobulin (Ig) levels for pediatric patients must be compared with normal laboratory values for age.

Many experts doubt the utility of IgG subclass measurements. [23, 19] Measuring functional or specific antibodies is important for determining the clinical relevance of a particular IgG subclass deficiency, and these tests can be obtained by several commercial reference laboratories. Patients may have normal total serum immunoglobulin and IgG subclass levels and still fail to make certain antibodies to bacterial or viral pathogens. The specific antibodies include tetanus/diphtheria antibodies (IgG1) and pneumococcal and meningococcal polysaccharides (IgG2 and IgG3). [24, 25]

Several methods are available for measuring IgG subclasses, the most common of which is enzyme-linked immunosorbent assay (ELISA) with either monoclonal or polyclonal antibodies. Radial immunodiffusion is rarely used in modern laboratories. Results vary according to the exact method and antibody combinations used. Therefore, results should be compared to age-specific norms generated in the same laboratory.

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Imaging Studies

Radiographic studies may help monitor pulmonary infections, document sinusitis, and identify the development of chronic pulmonary changes such as bronchiectasis.

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Other Tests

Pulmonary function studies also may be useful.

Cultures obtained by bronchoscopy or sinus endoscopy may be helpful in cases of chronic bronchitis, cough, or both.

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