Iodine Nutrition, Thyroid-stimulating Hormone, and Related Factors of Postpartum Women from three Different Areas in China: A Cross-sectional Survey

Objective Studies on the relationship between iodine,vitamin A(VA),and vitamin D(VD)and thyroid function are limited.This study aimed to analyze iodine and thyroid-stimulating hormone(TSH)status and their possible relationships with VA,VD,and other factors in postpartum women.Methods A total of 1,311 mothers(896 lactating and 415 non-lactating)from Hebei,Zhejiang,and Guangxi provinces were included in this study.The urinary iodine concentration(UIC),TSH,VA,and VD were measured.Results The median UIC of total and lactating participants were 142.00µg/L and 139.95µg/L,respectively.The median TSH,VA,and VD levels in all the participants were 1.89 mIU/L,0.44μg/mL,and 24.04 ng/mL,respectively.No differences in the UIC were found between lactating and non-lactating mothers.UIC and TSH levels were significantly different among the three provinces.The rural UIC was higher than the urban UIC.Obese mothers had a higher UIC and a higher prevalence of excessive TSH.Higher UICs and TSHs levels were observed in both the VD deficiency and insufficiency groups than in the VD-sufficient group.After adjustment,no linear correlation was observed between UIC and VA/VD.No interaction was found between vitamins A/D and UIC on TSH levels.Conclusion The mothers in the present study had no iodine deficiency.Region,area type,BMI,and VD may be related to the iodine status or TSH levels.

Basal Energy Expenditure of Chinese Healthy Adults:Comparison of Measured and Predicted Values

Objective This study aimed to measure the basal energy expenditure(BEE)of Chinese healthy adults and establish an accurate predictive equation for this population.Methods In total,470 Chinese healthy adults had their BEE measured using the Cosmed K4b2 portable metabolic system.Multiple linear regression analysis was applied to develop new optimal equations for predicting BEE.The bias,accuracy rate,concordance correlation coefficient(CCC),and root mean square error(RMSE)were used to evaluate the accuracy of the predictive equations.Results There was a significant difference in BEE between males and females,with 5,954 kJ/d and 5,089 kJ/d,respectively.People living in rural areas expended significantly higher BEE(5,885 kJ/d)than those in urban areas(5,279 kJ/d).Previous equations developed by Henry,Schofield,Harris-Benedict(HB),and Liu overestimated the BEE of Chinese healthy adults.The new equations derived from the present study displayed the smallest average bias and RMSE from the measured basal energy expenditure(mBEE).The CCC of the new equations was higher than other predictive equations,but it was lower than 0.8.There was no significant difference in the accuracy rate among all predictive equations.Conclusions Sex and regional differences in BEE were observed in Chinese healthy adults.Neither the widely used previous predictive equations nor the one derived in the present study were accurate enough for estimating the BEE of Chinese healthy adults.Further study is required to develop more accurate equations for predicting the BEE of Chinese healthy adults aged between 20–45 years.