Consumption pattern of iodised salt in households and serum TSH levels among 5-9 year old children in the plantation sector of Sri Lanka.

INTRODUCTION Salt is the main source of iodine in areas with high rainfall and iodine deficiency is the main cause of preventable hypothyroidism. Iodisation of salt increases iodine intake, but will depend on how salt is handled. This study was carried out to assess the pattern of salt consumption in the estate population and to ascertain the relationship between household salt iodine concentration and TSH levels in children. METHODS A descriptive cross sectional study was carried out in 20 randomly selected estates in the Ratnapura district of Sri Lanka, from August to November 2009. 1683 households with at least one child between 5-9 years were surveyed to determine patterns of salt usage. A salt sample from each household was tested for adequacy of iodine (concentration ≥ 30 ppm). In phase two, 519 children were randomly selected from these households and serum TSH levels were assayed. RESULTS Salt powder (54.5%) was preferred to salt crystals. Salt crystals were washed before use in 20% households. Salt was kept away from the fire-place in 90.4% of households. Salt samples of 88.7% households had an adequate iodine concentration. Salt iodine concentration was significantly lower when salt was stored near a fire-place and washed before use (p<0.001). The median TSH level of children from households with adequate salt iodine concentrations was significantly lower than that of children from households with inadequate salt iodine concentration (p<0.001). CONCLUSIONS A significant number of households did not have adequate iodine in salt samples probably due to inappropriate handling and storage. Consumption of salt low in iodine is associated with high serum TSH levels.