a cross-sectional morphometric study of thyroid glands in cadavers

Abstract

Introduction: Thyroid gland is an organ with a highly variable morphology. Despite several studies having been done to assess its measurements, a consensus has not been arrived at as to what constitutes a ‘normal’ thyroid. Aim: To determine the dimensions of the normal thyroid gland obtained from cadavers of South Indian region and to derive the mean and standard deviations of the measurements of the gland in the given population, thus contributing to the existing data. We also aimed to study three common but not constant components of the thyroid gland, namely Pyramidal Lobe (PL), Tubercle of Zukerkandl (TZ) and Levator Glandulae Thyroideae (LGT). Materials and Methods: The study was conducted on thyroid glands obtained from cadavers of South Indian region. Institutional ethics committee approval was obtained. Sixty thyroid glands were obtained from cadavers received for either routine dissection or autopsies. The thyroid glands were studied after adequate exposure and fixing in formalin. Dimensions were measured using Vernier calipers. Specimens with anomalies like absent isthmus etc were excluded from the study. Statistical analysis was done using the MedCalc Version 17.0 software. Results: The average dimensions of the lobes were: height 3.83 cm, width 2.62 cm, and thickness 2.69 cm. The average dimensions of the isthmus were: height 1.38 cm, width 1.36 cm and thickness 1.29 cm. The average dimensions of the pyramidal lobe were: height 2.03 cm, width at the base 1.91 cm and thickness 1.16 cm. Pyramidal lobe was present in 60% of cases. Levator glandulae thyroideae was observable in three cases (5%). Significant correlation was found between the dimensions of right and left lobes and regression equations were calculated. Conclusion: The dimensions of the thyroid gland are very variable. Knowledge of the wide ranging variations and measurements will be of help to surgeons and radiologists in correct interpretation, diagnosis and treatment of thyroid diseases.