Thyroid volume measurement by ultrasound in children as a tool for the assessment of mild iodine deficiency.

Thyroid ultrasound was used to measure thyroid volume in children and compared with thyroid palpation for the assessment of the prevalence of goiter in an area of mild iodine deficiency. School children, 6-14 yr old, were from control areas (n = 2693; urinary iodine excretion, 110 micrograms/L) or from an area of mild iodine deficiency (IDA; n = 278; urinary iodine excretion, 72 micrograms/L). Thyroid volume determined by ultrasound in control children increased with age (r = 0.62; P < 0.0001) and was significantly correlated with height (r = 0.51; P < 0.0001) and body weight (r = 0.126; P < 0.0001). Both median and mean thyroid volumes were greater in IDA children than in controls. The prevalence of goiter determined by ultrasound was 68 of 268 children (25.3%) in IDA and 105 of 2693 children (3.9%) in the control area (chi 2 = 204; P < 0.0001). Thyroid enlargement, as assessed by palpation, was found in 59 of 268 children (22%) in the IDA group and in 165 of 2693 (6.1%) subjects in the control area (chi 2 = 88; P < 0.0001). Some subjects of the IDA who were judged goitrous by palpation (11.2%) had a normal thyroid volume at ultrasound, and 12.7% of subjects with an abnormal thyroid volume at ultrasound were judged nongoitrous by palpation. In conclusion, 1) thyroid volume in children, as assessed by ultrasound, increases with age and is closely related to the parameters of body growth; 2) in every age group, thyroid ultrasound shows greater thyroid volume in an IDA group than in controls; and 3) a discrepancy between palpation and ultrasound is found in 23.9% of children living in an IDA, confirming that palpation is relatively inaccurate for assessing the prevalence of goiter in mild iodine deficiency. These data indicate that thyroid volume measurement by ultrasound in children provides a useful tool for the assessment of goiter in mild iodine deficiency.