Abstract
Background: Thyroxin hormone (T4) is produced by the thyroid glands which lies antero-lateral to the trachea. Computed tomography (CT) scan is
one of the commonly used imaging modality in the brain investigation. It uses X-ray which could induce biological effect on the thyroid gland that is highly radiosensitive. The study aimed to determine the effect of X-ray on Serum thyroxin hormone level in patients undergoing brain CT in Port Harcourt.
Methods: A prospective longitudinal study was carried out in Rivers State University Teaching Hospital in Port Harcourt with 60 participants sent for brain CT that fulfilled the study criteria. A 64 slice helical GE Optima CT machine was used. Patient venous blood was collected to measure serum thyroxin levels before, immediately, after and 7-day post exposure using Total Thyroxin Enzyme Immunoassay Test Kit. The thyroxin level of each participant was also recorded. The data collected was analyzed using SPSS windows version 22.0 statistical software. Pearson correlation and linear regression analysis models were used to evaluate correlation between the variables.
Results: The mean (±SD) serum thyroxin hormone levels in Preexposure, Immediate post-exposure, and 7-day post CT were 7.46 ± 1.30 μg/dl, 6.62 ± 1.78 μg/dl, and 7.89 ± 1.13μg/dl, respectively. There was no correlation between the pre exposure, immediate post exposure, and 7-day post exposure serum thyroxin levels. Conclusion: There was no effect of X-radiation on Serum thyroxin hormone level in patients undergoing brain CT in Port- Harcourt. Although the serum thyroxin level is not adversely affected, there is a great need to protect the thyroid gland.

Key words: Thyroxin hormone, computed tomography, X-ray, Port Harcourt.