Significance of the immunofluorescence staining patterns and titres of the antinuclear antibody test in paediatric rheumatology setting

BACKGROUND/AIM: Antinuclear antibody (ANA) is among the most frequently ordered tests in paediatric rheumatology setting. Diseases like systemic lupus erythematosus and Sjögren syndrome is closely related with a positive ANA and classified as ANA associated diseases. Besides, ANA test is ordered in patients with juvenile idiopathic arthritis (JIA) to assess the risk for uveitis and a positive ANA could be detected in children with nonrheumaticrheumatic conditions. In this study, we aimed to investigate frequency of positive ANA in paediatric rheumatology setting and the association of immunofluorescence staining patterns and titres of ANA with rheumatic diseases. MATERIALS AND METHODS: Immunofluorescence staining patterns, and titres of the ANA and diagnoses of children who tested for ANA between January 2016 and December 2021 were retrospectively analysed. RESULTS: Among 2477 patients with ANA tested, 28.1% had a positive ANA result. Among them, 39.2% had a diagnosis of a rheumatic disease. Most common rheumatic diagnosis was JIA (43.8%) and ANA associated diseases were observed in 24.5% of the patients with a rheumatic diagnosis. While ANA associated diseases had significantly more frequent homogenous staining, dense fine speckled pattern was significantly more common in children with nonrheumatic diagnoses. Despite ANA associated diseases was found to be significantly associated with higher titres, no difference was observed between patients with JIA and nonrheumatic conditions. CONCLUSION: Our study showed that the majority of children with a positive ANA test were not diagnosed with a rheumatic disease. While titres and patterns of ANA were found to be important in diagnosis of rheumatic diseases, ordering ANA test with solid indications might give improved probability of rheumatic diagnoses in children with a positive test.