Iodine deficiency disorders after a decade of universal salt iodization in a severe iodine deficiency region in China

Abstract

Background & objective: Universal salt iodization (USI) was implemented in all counties of China in 1995. This study was undertaken to assess the status of iodine deficiency disorders control and prevention after 10 years of implementation of USI in a severe iodine deficiency region in China.

Methods: Thirty primary school were selected in Gansu province utilizing cluster sampling methodology for the years 1995 and 2005. In each selected school, 40 children aged 8-10 yr were randomly selected for thyroid and IQ examination, and urinary samples were collected from 12. On the spot casual urine samples and salt samples were collected from a subset of children included in the study. In 2005, casual urine samples were also collected from 50 pregnant and lactating women in each cluster. Effect of health education was studied by a combination method of giving questionnaires to and observing students and families.

Results: The total goiter rates (TGR) were found to be 13.5 and 38.7 per cent in 2005 and 1995 respectively. The medians urinary iodine excretion levels of children were 191.8 and 119.9 mICROg/l in 2005 and 1995. The median urinary iodine excretion level of women was 161.9 mICROg/l. The mean intelligence quotient (IQ) was 96.9 in 2005 significantly more than that in 1997 (P<0.05). The health education pass rate of children and women were 21.1 and 51.1 per cent respectively.

Interpretation & conclusion: After ten years of universal salt iodization (USI), iodine nutrition of people improved and the current iodine nutrition status of population was adequate. Decrease in TGR and increase in IQ showed that IDD control and prevention had made great progress through ten years USI, salt iodization played the key role in IDD control and prevention for sustained elimination of IDD, the programme of USI and other measures like health education should be persisted and enforced.