Abstract
Biological significance of reverse triiodothyronine (rT3) is yet to be identified. Cord blood values reflect the fetal thyroid state as one of rT3, excess and triiodothyronine (T3) deficiency. Postnatally, T3 levels progressively rise and rT, levels fall.
In an attempt to correlate thyroid function and gestational age, TSH, T4, T3, and rT3, concentrations were measured by RIA on 50 cord blood samples. Infant gestational ages (GA) ranged from 29-42 weeks by the Ballard criteria; birth weights from 650-3870 grams.
Results show a significant positive correlation between gestational age, T3, and T4, and significant negative correlation between gestational age, rT3, and TSH. However, the rT3/T3 ratio offered the best coefficient of correlation as shown in the graphs
In conclusion, rT3/T3, ratio appears to represent a biological marker for gestational age.
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Isaac Alberto Hayek, R., Burstein, R. & Standefer, J. REVERSE TRIIODOTHYRONINE/TRIIODOTHYRONINE RATIO: A BIOLOGICAL MARKER FOR GESTATIONAL AGE. Pediatr Res 11, 426 (1977). https://doi.org/10.1203/00006450-197704000-00342
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DOI: https://doi.org/10.1203/00006450-197704000-00342
