Over 5 million infants have been screened for primary congenital hypothyroidism in California since 1980. This large number along with the multi-ethnic nature of California’s population allows for a detailed analysis of the effects of ethnic origin , sex, and their interaction on birth prevalence. Sex is the most important factor, with at least a 2 :1 (female : male) ratio across all major ethnic groups except blacks. The sex ratio among Hispanics is more striking; female cases out number male cases by a ratio of 3 :1 , and the birth prevalence for Hispanic fem ales is 1 in 1886 births. Previously published rates for Asians and blacks are suspect because of small sample sizes, and Hispanic rates also may be mislead in g if sex is not taken into account. These factors are important when screen in g tests, such as the serum T 4 test, are used as a statistical prescreening before thyroid stimulation hormone levels can be determined and before the influence of ethnic group and sex can be taken into account, because other factors may prevent high-risk groups (such as Hispanic females) from being declared positive.
Lorey, Fred W. and Cunningham, George C.
"Birth Prevalence of Primary Congenital Hypothyroidism by Sex and Ethnicity,"
4, Article 4.
Available at: http://digitalcommons.wayne.edu/humbiol/vol64/iss4/4