The New Zealand Laboratory Schedule and Test Guidelines: Immunology Tests

The Guidelines for immunology testing were developed by the Immunology subgroup, chaired by Dr Richard Steele. The group included a number of immunologists and allergy specialists from throughout New Zealand. Tests in the Schedule are divided into Tier 1, which all referrers can order, and Tier 2, meaning that the test must be ordered in conjunction with another health professional with a particular area of expertise. For some tests, additional clinical guidance is provided.

For further information on the New Zealand Laboratory Schedule see: www.dhbsharedservices.health.nz

Immunology tests

The immunology tests in the Laboratory Schedule were considered in the following categories:

• Allergy
• Autoimmune tests – ANCA
• Serological and genetic tests for coeliac disease
• Complement
• Infection
• Immunodeficiency
• Tests not funded

Many immunology tests are Tier Two tests

Immunological testing includes a wide range of tests which can have clinical relevance in a number of conditions including autoimmune disorders, immune deficiencies, malignancy, inflammatory disorders and allergic disease. Many of the tests in the immunology section of the Laboratory Schedule are defined as Tier Two and therefore should be ordered and interpreted with the assistance of a specialist in the particular clinical field. Interpretation of tests defined as Tier One often also requires discussion with a relevant specialist, e.g. an immunologist or rheumatologist.

Gliadin antibody tests are no longer funded (including native anti-gliadin antibody)

Gliadin antibody testing is now regarded as being unnecessary for the diagnosis of coeliac disease or “gluten sensitivity” and the test is no longer funded in New Zealand. Although this test was initially important and one of the few widely available tests for coeliac disease during the 1980s, testing using IgA tissue transglutaminase test is the now the preferred initial method in primary care.

Guidance has been developed for anti-neutrophil cytoplasmic antibody testing

A brief guideline has been developed which lists the vasculitic conditions in which anti-neutrophil cytoplasmic (ANCA) testing is indicated. The results of ANCA testing may be misleading if there is co-existing infection or conditions not included amongst those indicated in the guideline. ANCA testing is non-specific and confirmation of a diagnosis of a vasculitic condition often requires a tissue biopsy or discussion with a relevant specialist.