The frequency of co-positivity of anti-smooth muscle antibody and anti-nuclear antibodies and their contribution to the diagnosis of autoimmune hepatitis

Aim: Autoimmune hepatitis (AIH) is a chronic disease observed especially in women. The International Autoimmune Hepatitis Group recommends scoring systems for diagnosis using clinical and laboratory data. All scoring systems gave points to autoantibodies as anti-nuclear antibody (ANA) and anti-smooth muscle antibody (SMA) positivity. This study investigates the impact of the co-positivity of the ANA and SMA antibodies on the autoimmune hepatitis diagnosis. Material and Method: We monitored 78 autoimmune liver disease (autoimmune hepatitis, AIH) suspected patients with positive SMA antibody and then further tested for ANA between 2014 and2021. SMA test was screened at 1/40 and 1/100 titers and patients who were positive were taken to further dilution. The ANA test was screened at a titer of 1/40 and 1/160, a positive result was found to be repeated with advanced dilutions. All patients’ autoantibody scores of simplified AIH diagnostic system were calculated. Results: Seventy eight patients with positive SMA antibodies screened for ANA test with 1/40 and 1/160 titer, only 2 patients was found to be negative. The most frequently observed ANA pattern is cytoplasmic linear fibrils (68% ). The 95% ANA positive results was examined at a screening titer of 1/160. The 95% SMA positive results was found at a screening titer of 1/100. The autoantibody scores of 76 patients were +2, patient’s scores were +1. Conclusion: SMA antibody positivity is accompanied by a high rate of ANA antibody positivity but the co-positivity didn’t effect diagnostic score systems. On the other the co-positivity could be a sign of another associated autoimmune diseases.