Frequency and clinical Importance of Anti - TG auto antibodies [ATG]

ABSTRACT

To note the frequency of anti thyroglobulin autoantibodies [ATG] and its clinical importance in 25 follow-up cases of differentiated thyroid cancer [DTC]. Design: A case control study. Place and Duration of Study The total duration of study was one year [September 2000 to August 2001]. Majority of the patients included were the routine follow-up cases at IRNUM, Peshawar. However, few of the cases were also included from NORI, Islamabad and AFIP, Rawalpindi. Subjects and All the patients who had undergone sub-total or total thyroidectomy followed by I-131 ablation therapy were selected for this study. Thyroglobulin [Tg] and ATG were measured using immunometric assay technique with reference range of non-detectable to 40 IU/L. Patients with serum Tg level ' 10 ng/mL were included in group-1 [n=15] and all the remaining [n=10] in group-2. Overall, 11 patients showed ATG titer above the pre-defined threshold level. In group -1 patients, 8 had positive anti-Tg antibodies in their sera while in group-2, it was positive in only 3 cases. Risk of relapsing metastatic/recurrent disease in association with ATG was calculated which showed that patients with positive ATG have almost seven - fold increased risk of having recurrent/metastatic disease than those who do not. Samples for s-Tg measurements must also be evaluated for ATG status because more than one-third of these patients have positive ATG titer in their sera. Although in the presence of positive ATG, the risk of concurrent metastatic/recurrent thyroid disease is increased but still more studies are required to support its significance: