Influence of Physiological Factors on Thyroid Size Determined by Ultrasound

According to its superficial anatomical location, the thyroid gland is easily accessible by sonography. Sonography allows an exact documentation of the size and thyroid volume. The relationship between thyroid volume and anthropometric characteristics is a matter of controversy. The aim of this study was to investigate thyroid volume and its determinants in healthy adult. A cross-sectional study was performed from June2003 until April 2005 in 314 healthy adults aged over 18 years old in Yazd, Iran. Data were collected on age, sex, and weight and thyroid size by sonoraphy. Mean of thyroid volume in male and female was 9.08 ± 2.49 and 7.93 ± 3.2 milliliter which the differences was significant (P<0.003).Differences between thyroid volume and weight was significant (P=0.001). Mean of female weight and proportion of thyroid volume to their weight was 61.83 ± 12.09kg and 0.130 ± 0.33. Mean of male weight and proportion of thyroid volume to their weight was 71.41 ± 9.05kg and 0.126 ± 0.028 (P<0.003). Results of study is similar to other studies. Mean of thyroid volume in Yazd citizens is not differ from other Iranian but is different from other countries. This difference could be related to food intake habit, geographical region and daily oral iodine consumption.