Relevance of anti‐thyroperoxidase antibodies in immune thrombocytopenia in adults: A single‐centre cohort study

Relevance of anti-thyroperoxidase antibodies in immune thrombocytopenia in adults: A single-centre cohort studyTo the Editor, Immune thrombocytopenia (ITP) is an acquired autoimmune disorder causing potentially severe bleeding with isolated thrombocytopenia (platelet count <100 × 10 9 /L).Although treatment strategies are well established, biomarkers to predict first-line treatment response, relapse and long-term outcomes are lacking.Screening for anti-nuclear (ANA), anti-phospholipid (APL) or anti-thyroid autoantibodies (ATA) is suggested during the diagnostic process.1,2 ANA are detected in up to 20%-50% of patients with primary ITP 3,4 and may indicate a higher risk for chronic disease and overexposure to second-line therapies.ATA, particularly anti-thyroperoxidase (anti-TPO) antibodies, are found in 10%-30% of ITP patients.5 Anti-TPO antibodies are associated with other autoimmune diseases such as Hashimoto's thyroiditis and recurrent miscarriage.Their role in ITP remains unclear.In children, ATA positivity correlates with lower platelet counts at diagnosis but not with treatment response or disease duration.6 Given the lack of data regarding the role of ATA in adults with ITP, we conducted a retrospective cohort study to evaluate the prognostic value of anti-TPO in adults with ITP.Patients followed at the Department of Internal Medicine, University Hospital of Nice, France, aged 18 years or older, diagnosed with ITP, 2 having anti-TPO antibody measurement at diagnosis and ≥1 year follow-up were included.Demographic, clinical and biological data were collected at the time of ITP diagnosis and during follow-up.Anti-TPO antibodies were measured using the chemiluminescence analyser Atellica SII (Siemens, healthineers).The presence of anti-TPO antibodies was set when the value was over 60 mUI/L (Limit of Quantification [LOQ] < 28 mUI/L; Variation Coefficient [VC] < 5%).The study was approved by the Institutional Review Board of Nice University Hospital (IRB number 2025-710).Secondary ITP was defined as ITP associated with prevalent or concomitant chronic infection, autoimmune disease, haematological malignancy or primary immunodeficiency.Other patients were diagnosed with primary ITP.Severe bleeding was defined as a bleeding score >8.7 An overall response (OR) was defined as a platelet count >30 × 10 9 /L and at