Measurements of the effective thyroxine ratio (ETR) in the neonate, infant, and child.
The applicability of the effective thyroxine ratio (ETR) was assessed in euthyroid neonates, infants, and children. ETR determinations on cord blood fell within the normal adult range. In contrast, ETR values of newborns age 4 hr to 2 days were all elevated (1.17 -1.37) and within the hyperthyroid range for adults. Values in infants age 2 weeks and older and in children age 1-15 years all fell within the normal adult range. These findings suggest that the ETR can be used as an ancillary measure of thyroid function in infants and children. In the immediate postpartum period, however, ETR values may be normally in the adult hyperthyroid range.
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005312:Fetal Blood / Q000032:analysis; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007231:Infant, Newborn; D013974:Thyroxine / Q000097:blood*
D013974:Thyroxine