Abstract

PEREIRA, Denise N.  and  PROCIANOY, Renato S.. Effect of perinatal asphyxia on thyroid hormones. Rev. bol. ped. [online]. 2003, vol.42, n.2, pp.140-143. ISSN 1024-0675.

Objective: to verify the effect of perinatal asphyxia on thyroid hormone levels in term newborn infants. Methods: we carried out a case-control study with 17 term and asphyxiated (A) and 17 term and control (N) newborn infants at the Hospital de Clínicas de Porto Alegre. Patients were paired according to color of skin, sex, mode of delivery, gestational age, and weight at birth. We collected plasmatic T4, T3, free T4, reverse T3, and TSH of the umbilical cord after 18 to 24 hours of life and from asphyxiated and control newborn infants. Results: there were no differences in thyroid hormones of cord blood, with the exception of reverse T3, which was higher in A than in controls [median (percentile 25-75): A= 2(1.4-2); N= 1.41 (1.13-1.92); P=0.037)]. Thyroid hormone levels were lower in A than in controls on 18-24-hour after birth samples, except for reverse T3, which was similar in both groups [average ± SD: T4 A= 9.79 ± 2.59;\ N=14.68 ± 3.05; P<0.001; median T3 A= 40.83 (37.4-80.4); N= 164 (56.96-222.5); P=0.003; average ± SD: free T4 A=1.85 ± 0.92; N= 2.8 ± 0.74; P=0.004; median: reverse T3 A=1.54 (1.16-1.91); N=1.31(0.87-2); P=0.507; TSH A=9.1 (6.34-12.95); N=14.5(12.9- 17.85); P=0.008]. Conclusions: our data suggests that lower T4, free T4, and T3 levels are secondary to lower TSH levels in asphyxiated newborns; also, peripheral metabolism of T4 in asphyxiated infants can be altered due to low T3 and normal reverse T3 levels.

Keywords : perinatal asphyxia; thyroid hormones; euthyroid sick syndrome.