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Effect of passive smoking on thyroid function in infants
A Gasparoni1, M Autelli, M F Ravagni-Probizer
1Research Laboratories (Pediatric Oncohaematology and Neonatal Immunology, Policlinico San Matteo, IRCCS, Pavia, Italy.
Insights
Passive smoking significantly increases thyroglobulin (TG) and thiocyanate levels in infants born to smoking parents. These elevated thyroid function markers persist for at least one year, indicating long-term effects of secondhand smoke exposure.
Area of Science:
- Endocrinology
- Environmental Health
- Pediatrics
Background:
- Secondhand smoke exposure is a significant environmental health concern.
- Infant thyroid function is crucial for development and can be influenced by environmental factors.
Purpose of the Study:
- To investigate the impact of parental passive smoking on infant thyroid function.
- To assess thyroid-related markers, including thyroglobulin (TG) and thiocyanate, in infants exposed to varying levels of secondhand smoke.
Main Methods:
- A comparative study involving three groups of infants based on parental smoking status (non-smokers, father-smoker, both parents smokers).
- Measurement of cord serum and 1-year serum concentrations of thyroid hormones (T3, fT3, T4, fT4, TSH, TBG), thyroglobulin (TG), and thiocyanate.
- Statistical analysis to compare marker levels across the groups.
Main Results:
- No significant differences in T3, fT3, T4, fT4, TSH, or TBG levels were found among the groups.
- Significantly higher median concentrations of thyroglobulin (TG) and thiocyanate were observed at birth and at 1 year in infants of smoking parents compared to non-smoking parents.
- Elevated TG and thiocyanate levels persisted at 1 year in infants exposed to passive smoke.
Conclusions:
- Infants exposed to passive smoking, particularly from both parents, exhibit elevated thyroglobulin and thiocyanate levels.
- These changes in thyroid function markers suggest a potential direct effect of thiocyanate on the thyroid gland.
- The observed alterations in thyroid function can persist for at least one year with continued exposure to parental passive smoking.
Objective:
To evaluate the effect of passive smoking on thyroid function in infants.
Design And Methods:
Cord serum tri-iodiothyronine (T3), free T3 (fT3), thyroxine (T4), free T4 (fT4), TSH, thyroxine binding globulin (TBG), thyroglobulin (TG) and cord plasma thiocyanate were measured at birth, and serum TG and thiocyanate after 1 year of life, in 18 infants born from parents who did not smoke (group A), in 18 infants with a father who smoked (group B) and in 18 infants with parents both being smokers (group C).
Results:
No significant differences were observed in cord serum concentrations of T3, fT3, T4, fT4, TSH and TBG among the three groups. Median (range) TG concentrations (ng/ml) were 30.2 (5.0-102.0), 56.3 (20.5-208.0) and 76.0 (26.0-199.0) at birth (P=0.009 for groups A and B compared; P=0.0002 for groups A and C compared), and 14.9 (5.4-32.0), 19.5 (10.0-57.5) and 20.0 (14.0-40.7) at 1 year (P=0.017 for groups A and C compared), in the three groups respectively, and thiocyanate concentrations (mmol/l) were 3.3 (0.0-51.4), 12.9 (0.0-122.2) and 27.8 (3.3-184.5) at birth (P=0.015 for groups A and C compared), and 3.1 (0.0-32.7), 6.0 (0.0-47.3) and 20.3 (0.0-230.8) at 1 year (P=0.01 for groups A and C compared) in the three groups respectively.
Conclusions:
TG and thiocyanate concentrations at birth and at 1 year of age in infants of smoking parents are greater than in infants with non-smoking parents. These results indicate that the change in thyroid function as evaluated by serum TG concentrations observed at birth can persist at least for 1 year if the exposure to passive smoking from both parents is continued. Increased TG concentrations may be due to a direct effect of thiocyanate on the thyroid gland.