Hypothyroidism epidemiology

Arem R, Escalante D. Subclinical hypothyroidism Epidemiology, diagnosis, and significance. Adv Infern Med 1996 41 213-250. 

Thyroid status can be assessed using dried blood spot specimens for epidemiological surveys. Since TSH levels (as a marker of hypothyroidism) are stable in dried blood spot specimens for months this is the preferred assay for monitoring purposes. TSH monitoring is used in this way in India, China, Zaire, Thailand and Indonesia. 

Dixon, R. M., S. W. Reid, and C. T. Mooney. 1999. Epidemiological, chnical, hematological and biochemical characteristics of canine hypothyroidism. Veterinary Record 145 481 87. 

As discussed elsewhere in more detail (Morreale de Escobar et ai, 2004), it is inaccurate to assume, which has been very frequently done, that inhabitants of areas of ID are chnically hypothyroid individuals. The present experimental model supports the epidemiological findings that inhabitants of areas of ID are not clinically hypothyroid individuals, as their normal circulating T3 ensures euthyroidism of most tissues by extrathyroid adaptive mechanisms known to be operative in man when iodine availability decreases. But, as shown experimentally here, this does not avoid selective hypothyroidism of tissues, such as the brain, that depend mostly on T4 for their intracellular T3 supply. This selective hypothyroidism is aheady present in conditions of mildly decreased iodine availability, and may already negatively affect mental functions (Delange, 2001 Vitti et al., 2003 Vermiglio et ai, 2004). Indeed, inhabitants of areas of ID are often described as dull. Whole populations appear to wake up when their ID — and the consequent hypothyroxinemia — are corrected (Dunn, 1992). 

The relationship between maternal hypothyroidism and neurological damage in the offspring has already been established by several epidemiological studies in areas with severe ID (Delange, 1994) or normal dietary iodine intake (Haddow et al., 1999) and in animal models (Friedhoff et al., 2000 Dowling et al., 2000). Conversely, maternal... 

Epidemiological surveys have reported the prevalence of hypothyroidism of between 0.4% and 5.9% in elderly people (Sawin et al., 1979 Campbell et al, 1981 Parle et al, 1991 Bemben et al, 1994 Dlez et al, 2003 Wilson et al., 2006). In the Colorado Study (Canaris et al., 2000), the prevalence of overt hypothyroidism was 0.4% and that of subclinical hypothyroidism was 9%. In the NHANES III survey hypothyroidism was found in 4.6% (0.3% overt and 4.3% subchnical) of subjects (Hollowell et al., 2002). Both studies clearly showed that the prevalence of elevated TSH levels increased with age and was higher in women at all age groups. 

The results from the congenital hypothyroidism screening program were compared to the data of the epidemiological... 

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