Screening for Congenital Deficiency of Thyroid Hormone

[摘要] The Task Force on Genetic Screening was not able to discuss details of the various forms of genetic and metabolic screening.1 A Committee on Genetics was formed to examine these and other issues relating to congenital disease and medical genetics. The following statement is one of the Committee's reports.Congenital thyroid hormone deficiency is a prime example of a condition whose early diagnosis, as well as the opportunity for effective treatment, can be missed. The following report examines both the practice of newborn infant screening for early diagnosis of congenital thyroid hormone (T4) deficiency and the relation of that activity to the principles of metabolic (and genetic) screening.2 The reader is also referred to a parallel statement prepared by a committee of the American Thyroid Association.3BACKGROUND INFORMATIONThere is limited placental transport of thyrotropin (TSH) and the thyroid hormones 3,5,3'-triiodothyronine (T3) and thyroxine (T4). Serum T4 concentration in the newborn infant will be diminished when there is congenital deficiency of thyroid tissue, impaired activity of one of the enzymes involved in thyroid hormone biosynthesis (T4 hormone dysgenesis), deficient serum binding globulin (TBG), or deficient stimulation of thyroid (by TSH) or pituitary (by thyrotropin releasing hormone [TRH]). Primary congenital hypothyroidism (cretinism) is associated with a high frequency of mental retardation; cretinism accounts for about 1% to 2% of admissions to institutions for the mentally retarded. Only half of the patients with cretinism achieve IQs above 90 if diagnosis and treatment are delayed until 3 to 6 months of age, but 75% of patients achieve this outcome when clinical diagnosis is made and treatment begins before 3 months of age.4

[学科分类] 儿科学