Increased soluble Fas Serum Level associates with thyroid auto-antibody positivity in untreated Graves' hperthyroidism: A case-control study

Serum soluble Fas (sFas) increases in Graves’ disease (GD) and it may play a role in the pathogenesis of GD through interfering with the Fas-FasL interaction. To determine the association of serum sFas level with thyroid autoantibodies we evaluated the serum level of sFas and thyroid autoantibodies in 31 untreated GD patients and 37 re-lated healthy controls. Serum sFas level was significantly higher in patients (P<0.005) compared to controls. Odds ratios of thyroid autoantibodies serum positivity for serum sFas quartiles were 1.99 (95%CI: 1.2-3.3) for TSH receptor antibodies (TRAb), 1.68 (95%CI: 1.04-2.71) for thyroid peroxidase antibodies (TPOAb), 1.13 (95%CI: 0.7-1.83) for anti thyroid microsomal anti-bodies and 1.17 (95%CI: 0.73-1.88) for anti thyroglobulin antibodies. However, Odds ratios of quartiles of serum titer of thyroid autoantibodies for serum sFas were not significant. There was a moderate but significant direct correlation between serum levels of sFas and free T4 and free T3 (ρ=0.392 and ρ=0.360 respectively; P<0.05) in GD patients.