Thyroid status in the newborn infant: Effective thyroxine ratio and free thyroxine index
Open Access
- 1 March 1974
- journal article
- research article
- Published by BMJ in Archives of Disease in Childhood
- Vol. 49 (3) , 225-227
- https://doi.org/10.1136/adc.49.3.225
Abstract
The effective thyroxine ratio (ETR) was determined in 28 term and 17 premature infants at birth and in 17 infants aged 0 to 6 weeks. The mean values found were significantly higher than those in 20 adult euthyroid controls. Serum thyroxine (T4), T3 resin uptake ratio (T3 RUR), free thyroxine index (FTI), and ETR were determined in 14 term infants at birth. It was concluded that the raised T4 was partly due to an increase in thyroxine binding globulin but that there was also a degree of true thyroid hyperactivity. Serum thyroxine alone was not considered a suitable index of thyroid function in infants and the free thyroxine index or the effective thyroxine ratio was preferred instead.Keywords
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