New reference values for thyroid volume by ultrasound in iodine-sufficient schoolchildren: a World Health Organization/Nutrition for Health and Development Iodine Deficiency Study Group Report.
BACKGROUND
Goiter prevalence in school-age children is an indicator of the severity of iodine deficiency disorders (IDDs) in a population. In areas of mild-to-moderate IDDs, measurement of thyroid volume (Tvol) by ultrasound is preferable to palpation for grading goiter, but interpretation requires reference criteria from iodine-sufficient children.


OBJECTIVE
The study aim was to establish international reference values for Tvol by ultrasound in 6-12-y-old children that could be used to define goiter in the context of IDD monitoring.


METHODS
Tvol was measured by ultrasound in 6-12-y-old children living in areas of long-term iodine sufficiency in North and South America, central Europe, the eastern Mediterranean, Africa, and the western Pacific. Measurements were made by 2 experienced examiners using validated techniques. Data were log transformed, used to calculate percentiles on the basis of the Gaussian distribution, and then transformed back to the linear scale. Age- and body surface area (BSA)-specific 97th percentiles for Tvol were calculated for boys and girls.


RESULTS
The sample included 3529 children evenly divided between boys and girls at each year ( +/- SD age: 9.3 +/- 1.9 y). The range of median urinary iodine concentrations for the 6 study sites was 118-288 micro g/L. There were significant differences in age- and BSA-adjusted mean Tvols between sites, which suggests that population-specific references in countries with long-standing iodine sufficiency may be more accurate than is a single international reference. However, overall differences in age- and BSA-adjusted Tvols between sites were modest relative to the population and measurement variability, which supports the use of a single, site-independent set of references.


CONCLUSIONS
These new international reference values for Tvol by ultrasound can be used for goiter screening in the context of IDD monitoring.
Zimmermann
Michael B
MB
Laboratory for Human Nutrition, Swiss Federal Institute of Technology Zürich, Rüschlikon, Switzerland. michael.zimmermann@ilw.agrl.ethz.ch
Hess
Sonja Y
SY
Molinari
Luciano
L
De Benoist
Bruno
B
Delange
François
F
Braverman
Lewis E
LE
Fujieda
Kenji
K
Ito
Yoshiya
Y
Jooste
Pieter L
PL
Moosa
Khairya
K
Pearce
Elizabeth N
EN
Pretell
Eduardo A
EA
Shishiba
Yoshimasa
Y
D002648:Child; D005006:Ethnicity; D005260:Female; D014943:Global Health; D006042:Goiter / Q000145:classification / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D007455:Iodine / Q000172:deficiency* / Q000652:urine; D008297:Male; D015995:Prevalence; D012016:Reference Values; D012720:Severity of Illness Index; D017678:Sex Distribution; D014463:Ultrasonography
D007455:Iodine