Changes in Thyroglobulin Antibody Levels in Differentiated Thyroid Cancer Patients After Thyroidectomy: A Retrospective Study in Basrah, Iraq.

Introduction: Differentiated thyroid cancer (DTC), the most common endocrine malignancy is subdivided into papillary (the most common) and follicular type. Generally, DTC has a good prognosis with standard treatments such as surgery and, in some cases, radioactive iodine (RAI). Post-treatment follow-up includes thyroglobulin (Tg) and anti-thyroglobulin antibody (TgAb) measurement and imaging to assess treatment success and detect recurrence. However, TgAb can interfere with Tg measurements, making it essential to measure TgAb at different times (months).  Aim of the study: The aim of this study was to evaluate the changes in TgAb level in DTC patients after thyroidectomy and its association with recurrence.

Methods: This was a retrospective cohort study done at the Faiha Specialized Diabetes, Endocrine, and Metabolism Center (FDEMC), Basrah, Iraq, for individuals diagnosed with DTC between 2008 and 2023. The data collected were analyzed using IBM SPSS Statistics for Windows, Version 21.0 (Released 2012; IBM Corp., Armonk, New York, United States). The categories were classified according to the TgAb level as: (i) elevated (>115 IU/ml) and (ii) normal (<115 IU/ml), where TgAb levels measured at 0-6 months, 6-12 months, 24-36 months, 36-48 months, and beyond 48 months.

Results: The mean age at diagnosis of the study population (n=108) was 40.15 years with a female-to-male ratio of 4:1. Among these individuals, 52.8% (n=57) were found to be obese. Total thyroidectomy was performed on 84.3% (n=91). Papillary thyroid cancer was diagnosed in 69.5% (n=75). TgAb levels were influenced by body mass index (BMI); higher BMI (>30kg/m) was associated with less consistent TgAb normalization, particularly beyond 48 months (P = 0.04). The study found no significant differences in TgAb normalization based on gender, age, BMI, type of surgery, type of cancer, American Thyroid Association (ATA) risk of recurrence, or radioactive iodine (RAI) treatment.

Conclusion:  Factors including gender, age, type of surgery, type of cancer, ATA risk of recurrence, and RAI treatment did not significantly affect TgAb normalization in DTC individuals over the study period. However, higher BMI is associated with less consistent TgAb normalization in the long term.