Goiters prevalence

Table 13.1 Examples of the association between iodine in drinking water and goiter prevalence...

District Iodine content of drinking water (ng/i) Correlation to goiter prevalence References... 

Large-scale, epidemiologic cross-sectional trials are too cost-intensive to be used as an instrument for regular monitoring of IDD. Instead of cross-sectional trials, periodic prevalence surveys are an adequate method to evaluate changes in goiter prevalence/UI over time (WHO, 2001). 

Table 43.6 Change in total goiter prevalence between 1993 and 2003 by WHO region...

Iodine status assessments should also be based on food production surveillance and prospective clinical studies measuring Ul, iodine content in daily diets and goiter prevalence. 

Until the 1990s, total goiter prevalence (TGP) in school-age children was the primary indicator for the assessment of functional consequences of iodine deficiency in the population (WHO et al., 2001). Thyroid size was traditionally determined by palpation, but the reliability of this method is limited by high inter-observer and intra-observer variations. The measurement of thyroid size by ultrasound has therefore been an important step in the detection of mild-to-moderate iodine deficiency. International reference values for normal thyroid size are now available from iodine-sufficient children (Zimmermann et al., 2004). Because TGP is not a sensitive indicator of recent changes in iodine status in the... 

Figure 48.1 Total goiter prevalence (TGP) in 1993 and 2003 and percent change in 2003 by WHO region. Percent change in TOP from 1993 to 2003.

If compared to 1993 estimates, the current TGP data suggest that there is an overall increase of 31.7% in goiter prevalence throughout the world. The prevalence increased in the WHO regions of Africa, the Eastern Mediterranean, Europe and Southeast Asia, but decreased in the Americas and the Western Pacific (Figure 48.1). However, these data must be interpreted with much caution, as TGP does not reflect recent changes in iodine intake. Furthermore, the majority of the available TGP data in the time span of 1993—2003 were collected before 1998 — a time when many programs of iodine deficiency control had not yet been implemented (WHO et ai, 1993). 

Surveys on goiter in schoolchildren and on the iodine content of drinking water were conducted for the first time in four representative counties, namely, Houghton, Wexford, Midland and McComb. The prevalence of goiter was 38.6% among the 65537 school children studied. Salt containing potassium iodide (1 part in 5000) was introduced, and by 1929 the prevalence rate was reduced to 9% (Kimball, 1937). Brush and Airland (1952) conducted follow-up surveys on 53785 subjects in the same counties and found only 1.4% goiter prevalence. 

In 1972, spot checking of goiter prevalence in iodized salt areas showed negligible prevalence of goiter among school children, while uptake and excretion of urinary iodine had become normal, indicating a state of normal thyroid function and iodine nutrition. 

There has been a marked decline in goiter prevalence and an improvement in the functional status of thyroid, which has been achieved by normalizing iodine nutrition status after successful iodization programs in many countries however, goiter endemicity from severe to mild degrees still persists in many areas, indicating the existence of... 

Year Area Sample Goiter prevalence Urinary iodine ( ig/i)... 

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