2.4 IODINE DEFICIENCY IN ADULTS

The common result of iodine deficiency in adults is endemic goitre. One of its accompanying effects is a high degree of apathy as noted in populations living in iodine-deficient areas in northern India. This may even affect domestic animals such as dogs. It is apparent that reduced mental function is widely prevalent in iodine-deficient communities with effects on their capacity for initiative and decision-making. Characteristically there is an absence of classical clinical hypothyroidism, but laboratory evidence of hypothyroidism with reduced T-4 levels is common (Fig. 3). This is often accompanied by normal T-3 and raised TSH levels (Maberly et al., 1978; Zhu, 1983; Patel et al., 1973; Goslings et al., 1977).

Iodine administration in the form of iodized salt (Zhu, 1983), iodized bread (Clements, 1960) or iodized oil (Buttfield and Hetzel, 1967) have all been demonstrated as effective in preventing goitre in adults. Iodine supplementation may also reduce existing goitre (Fig.4). This is particularly true of iodized oil injections. The obvious benefit leads to ready acceptance of the measure by people living in iodine-deficient communities.

A rise in circulating thyroxine can be easily demonstrated in adult subjects following iodization (Fig. 3). As already pointed out, this could mean a rise in brain T-3 levels with improvement in brain function.

Figure 3. Effect of a single injection of iodized oil on the level of thyroid hormone (serum protein-bound iodine PBI) in subjects in the Papua New Guinea highlands. Each dot represents an individual. The horizontal lines show the mean level for each group. The figure shows that a single injection of iodized oil causes a rise in the level of thyroid hormone for up to four and a half years. (Reproduced from Buttfield and Hetzel, 1967, with permission). WHO 70219

Figure 4. Disappearance of goitre from the neck of a middle-aged woman in Papua New Guinea three months after the injection of iodized oil. (Reproduced from Buttfield and Hetzel, 1967, with permission). - A

Figure 4. Disappearance of goitre from the neck of a middle-aged woman in Papua New Guinea three months after the injection of iodized oil. (Reproduced from Buttfield and Hetzel, 1967, with permission). - B

The general social effects of iodization are demonstrated by the case of the Chinese village of Jixian near Jamusi in Heilongyang Province, northeast China (Li et al., 1985). In 1978 there were 1,313 people in the village with a goitre rate of 65 percent, and 11.4 percent of cretins. The cretins included many severe cases which caused the village to be known locally as "the village of idiots". Its economic development was hindered - for example, no truck driver or teacher was available. Girls from other villages did not want to marry and live there. The intelligence of the student population was known to be low; children aged 10 had a mental development equivalent to others aged 7. Iodized salt was introduced in 1978. The goitre rate had dropped to 4 percent by 1982. No cretins were born after 1978. The attitude of the people changed greatly - they were much more positive in their approach to life, in contrast with their attitude before iodization. The average income had increased from 43 Yuan per head in 1981 to 223 Yuan in 1982 and 414 Yuan in 1984, higher than the average per-caput income in the district. In 1983 cereals were exported for the first time. Before iodization, no family had a radio, but now 55 families had a TV set. Forty-four girls came from other villages to marry boys in Jixian. Seven men joined the People's Liberation Army whereas before they had been rejected because of goitre. These effects were due mainly to the correction of hypo-thyroidism by iodized salt. The social impact of IDD control programmes needs to be investigated further.