Serum Bruton's tyrosine kinase and NF-κB in Hashimoto's thyroiditis ‒ a case-control study of potential diagnostic biomarkers

Abstract

Introduction and aim. Hashimoto's thyroiditis (HT) is the leading cause of hypothyroidism, yet its diagnosis relies on markers with known limitations. Bruton's tyrosine kinase (Btk) and nuclear factor kappa B (NF-κB) are implicated in B-cell-mediated autoimmunity. This study aimed to explore the serum levels and preliminary diagnostic potential of Btk and NF-κB in Iraqi patients with HT. Material and methods. In this case-control study, 30 HT patients, 30 non-autoimmune hypothyroidism patients, and 60 healthy controls were enrolled from three centers in Karbala, Iraq. HT was defined by elevated TSH (>4.2 µIU/mL), reduced fT4 (<0.93 ng/dL), and positive anti-TPO and/or anti-Tg, whereas non-autoimmune hypothyroidism was defined by elevated TSH and low fT4 with negative thyroid autoantibodies. Serum Btk and NF-κB were measured by enzyme-linked immunosorbent assay. Thyroid hormones and autoantibodies were determined by electrochemiluminescence immunoassay. Receiver operating characteristic (ROC) analysis was performed to assess preliminary diagnostic accuracy for distinguishing HT from non-autoimmune hypothyroidism and healthy controls. Results. Serum Btk and NF-κB levels were significantly elevated in HT patients compared to both control groups (Btk: 7.81±0.98 vs. 7.00±0.77 vs. 6.10±1.60 ng/mL; NF-κB: 1.90±0.71 vs. 0.91±0.21 vs. 0.84±0.39 ng/mL, p<0.001). In ROC analysis, NF-κB showed an area under the curve (AUC) of 0.95 (95% CI: 0.89–0.99) for discriminating HT from non-autoimmune hypothyroidism. Both biomarkers correlated positively with anti-TPO, anti-Tg, and TSH, and negatively with fT4. Conclusion. Serum Btk and NF-κB were elevated in HT and showed preliminary associations with autoimmune activity. NF-κB, in particular, demonstrated promising initial diagnostic performance. These exploratory findings require validation in larger, independent cohorts.