(Application of Anti-Nuclear Antibody Test in Diagnosis of Systemic Autoimmune Rheumatic Diseases and Related Diseases)

Anti-nuclear antibody (ANA) is an example of autoantibodies that precedes the development of autoimmune diseases particularly systemic autoimmune rheumatic diseases. Thus, ANA is one of the most common laboratory tests requested by the clinician when there is suspicious of underlying autoimmune disease in a patient. There are various laboratory methods that can be used to detect ANA in patient's blood but for many years' indirect immunofluorescence (IF) is considered as a gold standard for ANA screening. The presence of ANA does not necessarily indicate the individual has autoimmune disease because the sensitivity and specificity of ANA varies according to the underlying diseases. Various laboratory methods were shown to have different sensitivity and specificity in detecting ANA. The interpretation of ANA and clinical diagnosis are also complicated because ANA can be detected in non-autoimmune conditions and in healthy population. Thus, interpretation of ANA requires appropriate clinical information to be clinically useful and at the same time can suggest if further laboratory test is needed. In recent years, ANA test through indirect immunofluorescence method has seen many new developments that include the establishment of the International Consensus of ANA Pattern (ICAP) and automated ANA IF reader. The direction of these new developments is towards harmonization of ANA reporting. This review will provide an overview of different methods of ANA testing, the clinical utility of ANA positivity and recent advances in ANA testing.

Automated summary

Anti-nuclear antibody (ANA) is a type of autoantibody that occurs before the development of autoimmune diseases. It is commonly used as a lab test to detect underlying autoimmune diseases in patients. Different laboratory methods have shown varying sensitivity and specificity in detecting ANA, and its interpretation is complex as it can be present in non-autoimmune conditions and healthy individuals. Recent advances in ANA testing aim to harmonize reporting and include the establishment of International Consensus of ANA Pattern (ICAP) and automated ANA IF reader.