Bruton Agammaglobulinemia Workup

Updated: Apr 22, 2019
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Workup

Laboratory Studies

Perform initial studies measuring quantitative IgG, IgM, immunoglobulin E (IgE), and immunoglobulin A (IgA) levels. IgG levels should be measured first, preferably after age 6 months, when maternal levels decline. IgG levels below 100 mg/dL are usually indicative of X-linked agammaglobulinemia (XLA). The detection of IgG, IgA, IgM, and IgE levels is related to age. Typically, IgM and IgA are undetectable. All levels are reduced in males with XLA. Age-specific reference range values are available to compare with the patient's level.

Once antibody levels are detected as abnormally low, confirmation is attained by using fluorocytometric analysis of B-lymphocyte and T-lymphocyte markers. CD19+ B-cell levels lower than 100 mg/dL are diagnostic of XLA. On fluorocytometric analysis, T-cell values (CD4+ and CD8+) are usually increased.

Further analysis can be made by detecting IgG responses to T-cell–dependent and T-cell–independent antigens by administering immunizations, such as an unconjugated 23-valent pneumococcal vaccine (T-cell–independent responses) or tetanus, diphtheria, and H influenzae type b immunization (T-cell–dependent responses).

Molecular genetic testing may establish an early confirmed diagnosis of congenital agammaglobulinemia and facilitate carrier detection and prenatal diagnosis. [28] . From a developing country, blood can be blotted onto the filter paper of Guthrie cards and shipped to a laboratory in the United States for sequencing. [29] In fact, the use of molecular genetic tests for early diagnosis should be stressed. [30]

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Imaging Studies

Head radiographs may demonstrate an absence of tonsils or adenoids. Further imaging studies of the chest can demonstrate chronic infections or sinopulmonary diseases.

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Other Tests

Pulmonary function tests are central to monitoring lung disease, of both the obstructive type and the restrictive type. They should be checked yearly in children who can perform the test (typically age 5 y).

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Procedures

Endoscopy and colonoscopy can be used to assess the extent and the progression of inflammatory bowel disease. Bronchoscopy can be useful in diagnosing and tracking chronic lung disease and infections.

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Histologic Findings

In patients with X-linked agammaglobulinemia (XLA), lymphoid tissues lack germinal centers, and plasma cells are missing from the lamina propria of the gut and from bone marrow stores. In tissue samples taken to evaluate infection, the most common finding is an intense inflammatory response.

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