Morphological asymmetry in thyroid lobes, and sex and handedness differences in healthy young subjects.

The aim of the present study was to investigate sex and handedness differences in the sizes of the right and left thyroid lobes. Subjects were 72 healthy university students (36 female and 36 male), 18 to 23 years of age. Hand preference was assessed using the Edinburgh Handedness Inventory. The volumes of the right and left thyroid lobes were measured by ultrasonography. The right lobe was larger than the left. The right and left lobes were larger in men than in women. There were no handedness difference in the total thyroid volume and the volume of right lobe. But, the left lobe was larger in right-handed subjects than in the left handed ones. The difference (right minus left) was statistically larger in left-handers than in right-handers. The sex-related differences may be attributed to the sex differences in body weight. It can be stated that handedness is associated with the asymmetry of thyroid lobes.