Pathogenesis of endemic goitre in Eastern Nigeria

Abstract

1. A survey in Eastern Nigeria revealed an area of endemic goitre with a marked variation in incidence form village to village not accounted for by iodine deficiency alone.2. As dried unfermented cassava was consumed in large quantities in the highly goitrous areas, experiments with rats were undertaken to assess the significance of this factor.3. Groups of rats were fed (a) cassava, (b) equal parts cassava and standard diet, (c) cassava with added iodine and (d) standard diet, and each rat received and intraperitioneal injection of 20 μc iodine 24 h before being killed.4. The iodine content and hardness of the water in the various areas were estimated and the chemical and bacteriological indices of pollution determined.5. The following effects were observed: thyroid weight, iodine uptake and plasma-protein-bound iodine were all increased in the cassava-fed animals, the last markedly so. the thyroid's precursor and hormone iodine stores were severely depleted in these animals, which also showed an impaired transfer of iodine from monoiodotyrosine to diiodotyrosine and a high proportion the iodine present as iodothyronine. The giving of iodine with the cassava did not prevent these changes from taking place.6. Many of the observed effects suggest that cassava was acting like the thionamide group of an antithyroid drug.7. These findings are discussed.