Congenital Hypothyroidism in Spanish-Surnamed Infants in Southern California: Increased Incidence and Clustering of Occurrence

Sir .—From January 1, 1981, through December 31, 1987, 113358 newborns were screened for congenital hypothyroidism at the Los Angeles Country University of Southern California Medical Center. Of these newborns, 107676 had a Spanish surname. The diagnosis of primary congenital hypothyroidism was confirmed in 55 infants with a Spanish surname. Forty-eight of these infants were born without a thyroid gland, 3 had dysgenesis of the thyroid gland, 3 had an inborn error of thyroid metabolism, and 1 had transient hypothyroidism. Thus, the incidence of permanent idiopathic congenital hypothyroidism (12 males and 39 females per 107676 newborns) in Spanish-surnamed infants is 1 per 2111, confirming findings from a preliminary report from this medical center. 1 This incidence is greater than the 1 per 32377 for the black population 2 and the 1 per 4254 for the white population. 3 Additionally, of the 51 newborns, 24 (6 males and 18 females) with permanent