Chapter 79 - Evaluating the Efficiency of Iodization Programs: Impact of Iodine Prophylaxis on Different Aspects of Life and Society

Abstract

Isolation of iodine from natural sources, its presence in the thyroid gland, and its importance in the treatment of goiter are the results of extensive studies of the nineteenth century, but necessary knowledge for successful prophylactic use in the prevention and control of iodine deficiency was initiated only in the latter part of the 20th century. The importance of iodine in the treatment of goiter is the outcome of studies of the nineteeth century, but its prophylactic use in the prevention of goiter and associated iodine deficiency disorders (IDD) was initiated only in the next century. Earlier iodization programs failed and fell into disrepute because of the use of overdoses of iodine, which results in excessive secretion of thyroid hormone, leading to a number of disorders. To evaluate the effectiveness of salt iodization programs, a large-scale study was organized in 1956 for the prevention of Himalayan endemic goiter in India. A follow-up study in 1962 showed a marked decrease in goiter prevalence, while 131I uptake and excretion of urinary iodine had become normal, indicating a state of normal thyroid. Excess iodine supplementation, however, is related to the further risk of thyroid disease. Occurrence of iodine-induced hypothyroidism and iodide-goiter, IIH and iodine-induced thyroiditis are the consequence of excess iodine supplementation in certain populations who were iodine deficient till 40 years or more of age. To make iodization programs fully successful, studies of environmental factors other than iodine deficiency are important in areas where IDD persists in spite of the recommended iodine intake being supplied.