In order to study the effect of levothyroxine in the treatment of endemic goitre, a longitudinal study was conducted among the Aborigines in Lanai Post and Sinderut Post, situated in an iodine-deficient area located in the district of Kuala Lipis, Pahang. All subjects in the treatment group (Lanai Post) were given 100 µg of levothyroxine per day and were followed for 1 1/2 years. A total of 311 subjects were examined at baseline, 323 on the first, 256 on the second, 239 on the third and 184 on the fourth visit following levothyroxine supplementation. Goitre prevalence, thyroid hormones, thyroid volume, nutritional status, urinary iodine levels, arterial blood pressure and mental performance were determined. Following the intervention, goitre prevalence was significantly reduced in the treatment group (baseline 42.8% vs final visit 13.0%, p<0.0001); however, no significant difference was noted in the control group. Total T4 levels were increased in the treatment group (p<0.0001), while a significant reduction was noted in the control group (p<0.0001). Thyroid-stimulating hormone levels increased significantly in the treatment group following 1 year of intervention, while no significant changes were observed in the control group. As for the thyroid volume, both groups showed a significant increment following the intervention (p<0.0001). With respect to the nutritional status, the treatment group showed a significant increase in body weight following the intervention (p<0.05). In addition, the mid-arm circumference and body mass index also increased after 1 year of intervention. However, the control group showed a reduction in the waist-hip ratio (p<0.0001). Although there was no statistical difference in the waist-hip ratio in the treatment group, there has been a significant reduction observed after 1 year of intervention. At 1 year, a reduction in skinfold thickness was noted in the treatment group while only the triceps and subscapular were increased in the control group. The body fat was decreased in the treatment group following 1 year of intervention (p<0.0001). No particular trend was noted in the urinary iodine excretion in the treatment group, but surprisingly, the levels were increased in the control group (p<0.0001). A significant increase in both systolic and diastolic blood pressures was observed in the treatment group following 1 year of intervention, but the controls showed a reduction in the systolic blood pressure (p<0.0001). Both groups showed a remarkable increase in mental performance, with a more pronounced effect in the treatment group (p<0.05). The correction of iodine deficiency by levothyroxine supplementation has a short-term beneficial effect in reducing the prevalence of goitre and improving the mental ability among the Aborigines in endemic areas; however, proper monitoring and close supervision are needed to maintain compliance.
Although endemic goitre is no longer a major public health problem in Malaysia, iodine deficiency still remains a significant problem in a few remote settlements. The aim of this study was to determine the effectiveness of iodized oil intervention in the prevention of endemic goitre among the indigenous people in Malaysia. A pretest and post-test controlled trial was conducted among primary schoolchildren and pregnant mothers in Lasah, Sungai Siput and Perak. Legap Post and Yum Post were selected as the intervention areas, while Perwor Post and Poi Post were taken as controls. The variables studied included thyroid hormone concentrations, thyroid volume, urinary iodine excretions and mental performance. A baseline and two follow-up visits were conducted in both intervention and control areas. Intervention subjects were given iodized oil in the form of capsules which were taken orally (Laboratoire Guerbet, Paris, France). There was a significant increase in serum thyroxine hormone (T4) concentrations (p<0.0001) and a significant decrease in thyroid stimulating hormone (TSH) concentrations (p<0.05) in the schoolchildren following the intervention, however, pregnant mothers did not show any significant changes in T4 and TSH concentrations. Thyroid size was significantly reduced in both groups (p<0.05). Urinary iodine excretions 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, as 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 awaiting national coverage for the salt iodization program.