Assessing Thyroid Function in Infants and Children
This chapter will review assessment of thyroid function through measurement of serum thyroid hormone and thyroid stimulating hormone (TSH) levels in infants and children. There are aspects of thyroid function that are unique to infants and children, as compared to thyroid function in adults. While serum TSH is the single most accurate test to diagnose hypo- or hyperthyroidism , age-related normal ranges are higher and vary with age more in infants and children as compared to adults . Further, a TSH level alone is not adequate to diagnose central hypothyroidism or thyroid hormone resistance. In addition, in the early stages of thyroid dysfunction, a serum TSH abnormality will precede an abnormality in thyroid hormone levels, e.g., mild or subclinical hypo- or hyperthyroidism. For all of these reasons, pediatric endocrinologists prefer to measure both serum TSH and serum free thyroxine (T4; or total T4) in the evaluation of patients with suspected thyroid dysfunction.
KeywordsThyroid Stimulate Hormone Subclinical Hypothyroidism Congenital Hypothyroidism Thyroid Stimulate Hormone Level Primary Hypothyroidism
- 2.Nelson JC, Clark SJ, Borut DL, et al. Age-related changes in serum thyroxine during childhood and adolescence. J Pediatr. 1993;123:889-905.Google Scholar
- 4.National Newborn Screening and Genetics Resource Center. National Newborn Screening Report—2000. Austin, TX: NNSGRC; February, 2003.Google Scholar
- 6.American Academy of Pediatrics; Rose SR, Section on Endocrinology and Committee on Genetics, American Thyroid Association; Brown RS, Public Health Committee, Lawson Wilkins Pediatric Endocrine Society, et al. Update of newborn screening and therapy for congenital hypothyroidism. Pediatrics. 2006;117:2290.CrossRefPubMedGoogle Scholar
- 17.Toft A, Beckett G. Measuring serum thyrotropin and thyroid hormone and assessing thyroid hormone transport. In: Braverman L, Utiger R, eds. Werner and Ingbar’s The Thyroid. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:329-344.Google Scholar
- 26.Fisher DA. Thyroid physiology in the perinatal period. Mead Johnson Symposium on Perinatal and Developmental Medicine. No.8. Marco Island, Florida; 1975.Google Scholar