Sonographic Evaluation of Normal Thyroid Gland Volume in Nigerian Adults: A Cross-Sectional Study in Benin City

Background : Thyroid volume reference values are highly essential for diagnosing goitre and monitoring treatment. It varies across populations due to genetic, environmental, and geographical factors. This study aims to establish reference ranges for thyroid gland volume in Nigerian adults using ultrasonography and to assess correlations with demographic and anthropometric variables. Methods : A prospective cross-sectional study was conducted at the University of Benin Teaching Hospital from January to December 2010. 384 healthy adult volunteers without history of thyroid disease underwent thyroid ultrasonography. Thyroid lobe volumes were calculated. Anthropometric measurements including weight, height, BMI, and BSA were recorded. Statistical analysis was performed using SPSS version 16.0 with Pearson correlation coefficient for variable relationships. Results : The median total thyroid gland volume was 13.20 cm^3 in males and 9.22 cm^3 in females (p<0.05) Mean thyroid volumes were 13.37±0.48 cm³ in males and 9.41±0.48 cm^3 in females, with males having significantly larger volumes (p<0.001). Thyroid volume correlated positively with height (p<0.05), body surface area (p<0.05), weight (p<0.05), and body mass index( p<0.05). Height and BSA were the strongest predictors. Right-handed individuals had larger left thyroid lobes (6.29±0.86 cm^3 ), compared to right lobes (5.79±0.72 cm^3 ), while left-handed individuals showed reversed asymmetry (p<0.05). Conclusions : This study establishes reference ranges for thyroid volume in Nigerian adults with significant gender differences and correlations with anthropometric parameters, particularly height and BSA. These values are essential for clinical assessment of thyroid enlargement in the Nigerian population and demonstrate substantially lower volumes compared to international reference values.