How is primary immunodeficiency diagnosed?

Laboratory tests are used to determine the exact nature of the immunodeficiency. Most tests are performed on blood samples.

Primary Raynaud's disease is diagnosed following the Allen Brown criteria

Diagnosis is based on the observance of the muscle weakness and the progressive worsening of the weakness. The diagnosis can be delayed because the disease is mistaken for ALS.

Blood tests strongly suggest the correct diagnosis, but a liver biopsy is needed for confirmation. It is also usually necessary to x ray the biliary system to look for other causes of obstruction.

The main diagnostic test that distinguishes common variable immunodeficiency from other immunodeficiency diseases is the low antibody level despite the normal number of B cells. Antibody levels are...