RESUMEN
Cord blood samples, as sera (n=4,753) and dried blood spots (n=855) obtained from subjects in iodinedeficient districts in northern Thailand, were studied for T4 and TSH. The methodology was optimized by the used of NETRIA bilk reagents and in-house methods were developed to adapt them for cost reduction, convenience and precision/accuracy. The biochemical findings with cut-off values at < 3 µg/dl for T4 and >50 mIU/L for TSH as confirmed by <1ng/dl for FT47 showed 16 cases (0.34%) of neonatal chemical hypothyroidism (NCH) varying from 0.18 to 1.59 percent of 4,753 cases. Out of the total 4,753 cases, 1.45 percent (n=96) could benefit from thyroxine administration. In this research project, the screening indicated a mild to moderate degree of IDD severity. The findings are useful for epidemiological monitoring and for advocacy of the IDD prevention and control programme.