One in every 3,500 new-born babies world-wide is affected by a thyroid deficiency. Up to 1 in 900 babies are born with this deficiency in regions with low iodine diets. Neonatal hypothyroidism leads to mental retardation and intellectual impairment.
If the disease is detected within the earliest days of life and the child is treated promptly with a hormonal replacement, it will grow up to be normal and healthy. Proper detection requires screening all new-borns. So over the past 10 years, the International Atomic Energy Agency (IAEA) has been supporting national and regional screening programs in more than 20 developing countries in Africa, Asia and Latin America, using the Radioimmunoassay (RIA) technique. Recent achievements in this field were presented today during an IAEA/WHO Symposium on Global Perspectives of Nuclear Medicine at the 7th World Congress of Nuclear Medicine and Biology, held in Berlin, Germany, from 30 August to 4 September 1998.
RIA is a simple and cost-effective diagnostic technique for screening new-borns on a national scale. No radioactivity is administered to the patient. A drop of the baby's blood is applied to a test card and analysed in a laboratory. The amount of radioactive tracer (<sup125< sup=""> Iodine) used in most assays is minimal. RIA is easy to learn and robust enough to be applied even in developing countries with adverse environmental conditions such as high temperature and humidity.
With IAEA assistance, for example, Thailand is expected to test all of the country's new-borns (1.2 million per year) by the year 2000. In Latin America, over 3,000,000 babies are being screened per year. Uruguay has already reached 100% screening coverage during the past four years, and three other Latin American countries are now screening over 85% of their infant population.
Support to national laboratories has included the supplies, or where possible the local production, of reagents (monoclonal antiboides against human Thyroid Stimulating Hormones - hTSH and recombinant hTSH), state-of-the-art equipment for diagnosis, computer software, expert services and quality control, including safety procedures as part of the IAEA training. Interactive multimedia educational software is being developed to help train doctors and technicians.
The key to success and sustainability of developing country screening programs is the balance between cost and quality of the hTSH tests. The Agency helped the Uruguayan Nuclear Medicine Center in Montevideo bring the costs of reagents down to just $1 per test. "All attempts at starting a national screening program had failed until the InternationalAtomic Energy Agency helped us to produce the RIA reagents locally", explains Dr. Alicia Aznarez of the Nuclear Medicine Centre, who is in charge of the Uruguayan screening program and presenting its results at the Symposium. To date, 68 positive cases have been identified in Uruguay and undergone appropriate treatment. A 1994 governmental mandate to screen new-borns for hypothyroidism and wide acceptance amongst the country's medical community, health authorities and parents has contributed to the program's success.
National screening systems in developing countries, set up with the help of the IAEA, have an additional advantage. They facilitate early diagnosis and timely treatment of other inborn diseases, including cystic fibrosis and other errors of metabolism. In several countries, the IAEA supports these projects by introducing nuclear-based techniques, such as the polymerase chain reaction (PCR).