Effect of passive smoking on thyroid function in neonates

ABSTRACT

To evaluate the effect of passive smoking on thyroid function in infants. Cord serum Tri-iodothyronine [T3], Thyroxine [T4], Serum thyroid stimulating hormone [TSH], Thyroglobulin [Tg], and cord plasma thiocyanate [SCN] were measured at birth in 43 infants born to smoking fathers, and in 40 infants whose both parents were non-smokers. No significant differences were observed in cord serum concentrations of T3, T4 and TSH among the two groups. Tg and SCN concentrations were significantly higher in the study group than in controls [p<0.0001]. T3, T4, TSH were not correlated with SCN values, while there was strong [+ve] correlation between Tg and SCN [r=0.97]. Birth weight was significantly higher in controls than in the study group and, by regression, it was affected mainly by gestational age, and was not affected by SCN. Passive smoking during pregnancy may be responsible for elevated serum levels of thyroglobulin due to a direct effect of thiocyanate on the thyroid gland