Test Directory

Immunoglobulin G, subclass 4 (IgG4) antibodies to specific allergens have not been proved to be involved in pathogenesis of disease. The presence of IgG4 against otherwise innocuous antigens (such as foods) in serum simply indicates that the individual has been exposed to antigens that are recognized as foreign entities by the immune system. The presence of food-specific IgG4 alone cannot be taken as evidence of allergy or autoimmune disease and only indicates immunologic sensitization by the food in question (1). Thus, the quantitative IgG4 test should only be ordered by specialist who recognize the limitations of the test.

Preferred Specimen Type: Serum

Preferred Collection Container: Gold Top, Serum Separator

Alternate Collection Container: Red Top, Plain

Desired Specimen Volume: 0.3 mL Serum

1. Collect specimen in gold top, serum separator tube or red top, plain tube via venipuncture
2. Centrifuge and transfer serum to plastic aliquot tube

Transport to the laboratory refrigerated. 

Gross hemolysis; gross lipemia

See patient report.