Thyroid volumes in US and Bangladeshi schoolchildren: comparison with European schoolchildren

Abstract

Objective: The World Health Organization (WHO) recently adopted thyroid volume ultrasonography results from European schoolchildren as the international reference for assessing iodine deficiency disorders. Our objective was to describe thyroid volumes measured by ultrasonography in US and Bangladeshi schoolchildren and compare these with European schoolchildren. Methods: Cross-sectional studies were performed in schoolchildren in the US (n = 302) and Bangladesh (n = 398). Data were collected on the following: thyroid size by palpation and ultrasonography; urinary iodine; age; sex; weight; and height. Results: Applying the new WHO thyroid volume references to the Bangladeshi children resulted in prevalence estimates of enlarged thyroid of 26% based on body surface area (BSA) and 7% based on age. In contrast, in the US children, the prevalence estimates were less than 1% for each reference. In the US children, the best single predictor of thyroid volume was BSA (R 2 = 0.32), followed by weight (R 2 = 0.31). Using linear regression, upper normal limits (97th percentile) of thyroid volume from US children were calculated for BSA, weight and age, and were found to be lower than the corresponding references based on BSA and age from European schoolchildren. Conclusions: In areas with malnutrition, such as Bangladesh, the BSA reference should be preferred to the reference based on age. Results from the US children indicated that a thyroid volume reference based on weight alone would perform as well as the one based on BSA. European schoolchildren had larger thyroids than US children, perhaps due to a residual effect of iodine deficiency in the recent past in some areas in Europe.

Mild iodine deficiency in a sample of New Zealand schoolchildren

“…There were no significant differences between the median thyroid volumes of boys and girls in this study. Only Delange et al (1997) and Foo et al (1999) report significant differences in thyroid volumes between boys and girls, while most other studies have found no differences (Hess & Zimmermann, 2000;Langer et al, 1994;Liesenkötter et al, 1997;Vitti et al, 1994;Xu et al, 1999). Foo et al (1999) state, however, that in their study the differences in thyroid volumes between boys and girls were small and suggest a unisex reference for children aged up to 10 y old.…”

“…There has been discussion in the literature regarding the appropriateness of the 1997 reference data; the WHO=ICCIDD=UNICEF median and ULN values are similar to those found in a few studies of iodine-replete children (Büurgi et al, 1999;Vitti et al, 1994), but higher than those found in a number of other studies (Foo et al, 1999;Gutekunst & Martin-Teichert, 1993;Hess & Zimmermann, 2000;Liesenkötter et al, 1997;Xu et al, 1999). Recently a set of provisional reference values has been published that are approximately 30% smaller than the 1997 values, in an effort to correct for the large systematic measurement bias shown to be apparent in the 1997 reference data (Zimmerman et al, 2001).…”

“…The 95% confidence intervals in our data indicate that a number of girls fall just below the cut-off, suggesting that if the ULN values for girls were lower (ie closer to the values for boys) more girls in our study would have been classified with an enlarged thyroid gland. Xu et al (1999) propose that the larger thyroid volumes seen in girls in the Delange et al (1997) data might be the result of two factors. Firstly, girls are more affected by marginal iodine deficiency than boys, and secondly, that despite an adequate urinary iodine concentration the thyroid glands of girls take longer to regress than boys after iodine intervention.…”

Impact of protein energy malnutrition on thyroid size in an iodine deficient population of Gujarat (India): Is it an aetiological factor for goiter?

“…Previous studies have shown that the best predictors of thyroid size in normal iodine sufficient children are BSA, weight, height and age whereas WAZ, HAZ and WHZ are less predictive of thyroid volume (15). These authors did not measure other anthropometric parameters of nutrition such as MUAC, TC and TSF.…”

Toward a consensus on reference values for thyroid volume in iodine-replete schoolchildren: results of a workshop on inter-observer and inter-equipment variation in sonographic measurement of thyroid volume

“…However, several reports have suggested these reference criteria may be too high. T vol values in iodine-sufficient US children (3), Swiss children (4) and Malaysian children (5) are smaller than those of the European children from whom the WHO normative data are derived (6). In addition, two investigative teams have recently reported large differences (10±56%) in sonographic T vol in iodine-sufficient Swiss schoolchildren (4,7).…”