Effect of iodized oil supplementation on thyroid hormone levels and mentalperformance among Orang Asli schoolchildren and pregnant mothers in an endemic goitre area in Peninsular Malaysia

Although endemic goitre is no longer a major public health problem in Malay sia, iodine deficiency still remains a significant problem in a few remote settlements. The aim of this study was to determine the effectiveness of io dized oil intervention in the prevention of endemic goitre among the indige nous people in Malaysia. A pretest and post-test controlled trial was condu cted among primary schoolchildren and pregnant mothers in Lasah, Sungai Sip ut and Perak. Legap Post and Yum Post were selected as the intervention are as, while Perwor Post and Poi Post were taken as controls. The variables st udied included thyroid hormone concentrations, thyroid volume, urinary iodi ne excretions and mental performance. A baseline and two follow-up visits w ere conducted in both intervention and control areas. Intervention subjects were given iodized oil in the form of capsules which were taken orally (La boratoire Guerbet, Paris, France). There was a significant increase in seru m thyroxine hormone (T4) concentrations (P < 0.0001) and a significant decr ease in thyroid stimulating hormone (TSH) concentrations (P < 0.05) in the schoolchildren following the intervention, however, pregnant mothers did no t show any significant changes in T4 and TSH concentrations. Thyroid size w as significantly reduced in both groups (P < 0.05). Urinary iodine excretio ns showed a significant increase in both groups following the intervention (P < 0.01). However, mental performance in schoolchildren was not affected. In conclusion, iodized oil (oral) is effective in reducing thyroid size, a s well as improving the supply of iodine among schoolchildren and pregnant mothers in endemic goitre areas; however, its long-term effects need to be monitored closely. This method can be considered as an alternative while aw aiting national coverage for the salt iodization program.