Prevalence and clinical significance of elevated antinuclear antibody test in children and adult patients with idiopathic thrombocytopenic purpura

Background To determine the clinical significance of the antinuclear antibody (ANA) test in children and adult patients with idiopathic thrombocytopenic purpura (ITP). Method We conducted a retrospective analysis of 365 children and 108 adult patients with ITP. Patients found to have positive ANA were regularly followed-up by an experienced hematologist until December 2006 for development of symptoms indicative of autoimmune disorder. Mean follow-up 3.6 years (range: 2.1-7 years) for all patients. At the time of diagnosis of ITP, patients with connective tissue diseases (CTD) were excluded. Out of 365 childhood ITP; 301 (82.4%) patients were acute, 64 (17.6%) patients were chronic ITP. ANA titer :1:80 were positive in 33 (9.04%) of 365 patients with childhood ITP; 21 patients (6.9%) were in acute, and 12 patients (18.7%) were in chronic group. Out of 108 adult patients with ITP; 31 (28.7%) patients were acute and 77 (71.3%) patients were chronic ITP cases. ANA titer >= 1:80 were positive in 36 (33.3%) of 108 patients with adult ITP; 12 patients (38.8%) were in acute, and 24 patients (31.2%) were in chronic group. At the end of follow-up period Sjogren's syndrome (SS) was diagnosed in only one adult chronic ITP cases. None of the other ANA positive patients developed SLE or other CTD. Conclusions Our data demonstrated that ANA positivity is often found in adult and children patients with ITP, and indicate that the detection of ANA positivity is not enough to identify those patients with ITP who are at risk of developing SLE or other CTD. There is a statistically significant difference in terms of ANA positivity between childhood acute and chronic ITP patients. We think that ANA positivity may be an indicator in terms of chronicity for childhood ITP. However, large-scale studies should be considered to determine the significance of ANA positivity and their utility in differentiating acute from chronic ITP.