The volumes of the thyroid gland in adults aged 18-65 years in Czech republic - determination of the norms
Abstract
Objective: In the areas with moderate iodine deficit the sonographic examination of thyroid gland is a precious method of precise determination of its volume. The objective of the work was the sonographic examination of males and females aged 18-65 years and to determine the norms of the volumes of thyroid gland.
Methods and results: In total, by random sampling, there were sonographically examined 3 416 adults in 11 areas of the Czech Republic; there was chosen a set of 971 females and 681 males whose iodinuria level in first morning urine sample was equal or higher than 100 μg/l. This set was divided according to sex and into the age categories in 5-year interval.
The measurement of 3 dimensions of the thyroid gland was determined by Medison-Kretz SA 600 sonographic device with the use of 7.5 MHz linear probe for the depth and width measurement and 3.5 MHz probe was used for the lengths measurement. The volume was determined for each lobe individually using Brunn's formula: V (ml) = 0.479 x length x depth x width.
Our results imply the age-related increase of the volume of thyroid gland at both sexes (F-ratio = 1.99, p < 0.0001). At men and women the volume of thyroid gland fluently increases to the 30th year equally, from 30 years to 55 years it increases more rapidly in men while in women there is observed a moderate plateau.
Further increase of the volume of thyroid gland is equally fluent from the age of 55 years. Conclusion: We managed to determine first own norms of the volumes of thyroid gland for men and women aged 18-65 years in the Czech Republic in five-year age categories.
In terms of practical use we recommend 90th percentile as a limit for the evaluation of upper limit of thyroid gland and the 10th percentile for the evaluation of lower limit of the volume of thyroid gland.