Abstract Background: The frequency of overweight and obese children has increased worldwide, particularly in economically developed countries. No studies have been conducted to verify whether the increasing frequency of overweight and obesity in schoolchildren may affect the evaluation of iodine nutritional status in populations. The aim of this study was to verify whether urinary iodine concentration, thyroid volume and thyroid hypoechoic pattern may be affected by body mass index (BMI) in schoolchildren. Methods: The children included in this study (age 11-13 years) were a part of the schoolchildren recruited in the second nationwide survey (period 2015-2019) conducted in Italy to monitor the nationwide iodine prophylaxis program. Specifically, 1281 schoolchildren residing in iodine-sufficient areas (IS-group) and 384 children residing in a still mildly iodine deficient area (ID-group) were recruited between January and March 2015 in the first degree secondary state schools. In all the children, spot urinary iodine concentration (UIC) was measured, thyroid ultrasound was performed to evaluate thyroid volume (TV), and hypoechogenicity was assessed to indirectly evaluate iodine-associated thyroid autoimmunity. Results: The frequency of overweight (OW), obese (OB), and adequate weight (AW) children were similar in IS- and ID-group at any age. After adjusting by sex and age, the regression analysis showed lower UIC values in OB than in AW children of IS-group (beta coefficient = -34.09; 95% CI: -65.3; -2.8), whereas no significant differences were observed in ID-group. Both in IS- and ID-group, the distribution of TV in AW children was significantly shifted towards lower values in comparison to the distribution of OB children (P<0.001 in IS-group; P=0.012 in ID-group). Furthermore, the frequency of thyroid hypoechogenicity was higher in ID- than in IS-group (10.9% vs 6.6%, P=0.005), in both groups however, it was significantly lower in AW than OB children (P<0.01) Conclusions. This study for the first time demonstrates that BMI may be a confounding factor in monitoring iodine nutritional status in schoolchildren. Since in Italy as in other Western countries the number of OW and OB children is high, BMI is a factor to consider in monitoring salt iodization programs worldwide.
Obesity and monitoring iodine nutritional status in schoolchildren: is body mass index a factor to consider?
Tonacchera M;Di Cosmo C;
2020-01-01
Abstract
Abstract Background: The frequency of overweight and obese children has increased worldwide, particularly in economically developed countries. No studies have been conducted to verify whether the increasing frequency of overweight and obesity in schoolchildren may affect the evaluation of iodine nutritional status in populations. The aim of this study was to verify whether urinary iodine concentration, thyroid volume and thyroid hypoechoic pattern may be affected by body mass index (BMI) in schoolchildren. Methods: The children included in this study (age 11-13 years) were a part of the schoolchildren recruited in the second nationwide survey (period 2015-2019) conducted in Italy to monitor the nationwide iodine prophylaxis program. Specifically, 1281 schoolchildren residing in iodine-sufficient areas (IS-group) and 384 children residing in a still mildly iodine deficient area (ID-group) were recruited between January and March 2015 in the first degree secondary state schools. In all the children, spot urinary iodine concentration (UIC) was measured, thyroid ultrasound was performed to evaluate thyroid volume (TV), and hypoechogenicity was assessed to indirectly evaluate iodine-associated thyroid autoimmunity. Results: The frequency of overweight (OW), obese (OB), and adequate weight (AW) children were similar in IS- and ID-group at any age. After adjusting by sex and age, the regression analysis showed lower UIC values in OB than in AW children of IS-group (beta coefficient = -34.09; 95% CI: -65.3; -2.8), whereas no significant differences were observed in ID-group. Both in IS- and ID-group, the distribution of TV in AW children was significantly shifted towards lower values in comparison to the distribution of OB children (P<0.001 in IS-group; P=0.012 in ID-group). Furthermore, the frequency of thyroid hypoechogenicity was higher in ID- than in IS-group (10.9% vs 6.6%, P=0.005), in both groups however, it was significantly lower in AW than OB children (P<0.01) Conclusions. This study for the first time demonstrates that BMI may be a confounding factor in monitoring iodine nutritional status in schoolchildren. Since in Italy as in other Western countries the number of OW and OB children is high, BMI is a factor to consider in monitoring salt iodization programs worldwide.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
