The Influence of the Use of Iodine during Perinatal Period on the Screening Test for Congenital Hypothyroidism

ABSTRACT

PURPOSE: This study was performed to detect the diseases of congenital hypothyroidism by the neonatal mass screening test early and to demonstrate the possible role of topical iodinated antiseptics(povidone-iodine, PVP-I) on transient hyperthyrotropinemia in newborn infants. METHODS: We performed neonatal screening tests for inborn errors of metabolism since 1985 by Guthrie test for PKU, maple syrup urine disease, histidinemia, and homocystinuria and enzyme-linked immunosorbent test for TSH. And for our prospective study, 366 newborns with a appropriate gestational age (between 37 and 42 weeks) were submitted to TSH screening test. We divided the study subjects into 4 groups; the group used PVP-I for mother and alcohol for cord care was categorized as Group A, the group used PVP-I for both mother and cord care as Group B, the group used triple dye for mother and PVP-I for cord care as Group C, and the group used triple dye for mother and alcohol for cord as Group D. RESULTS: 1) By neonatal screening test for inborn errors of metabolism during the last 10 years, we detected one case of phenylketonuria (PKU), one case of histidinemia and 28 cases of congenital hypothyroidism. The incidence of congenital hypothyroidism was 1 in 3,918 live births. 2) The mean TSH levels were 6.25+/-5.09 microU/ml(male 5.85+/-4.77 and female 6.6+/-5.41 microU/ml) in Group A, 8.30+/-7.68 microU/ml(male 6.30+/-7.15 and female 9.98+/-7.77U/ml) in Group B, 7.42+/-5.35 microU/ml(male 7.40+/-6.11 and female 7.44+/-4.63 microU/ml) in Group C, and 6.33+/-1.95 microU/ml(male 6.19+/-1.90 and female 6.42+/-2.03 microU/ml) in Group D, There were statistically significance between Group A and Group B, and Group D, but there was no statistically significance between gender. 3) The number of the newborns showed high levels of TSH over 15 muU/ml were 4.2%, 26.7% and 7.7% in Group A, B, and C, respectively. But nobody showed high TSH level over 15 microU/ml in Group D without use of PVP-I. CONCLUSIONS: In conclusion, we might be concerned for neonatal mass screening test on a national scale to prevent mental retardation and it is necessary to switch the povidone-iodine to other preparations as a perinatal antiseptics because of the possibility of the effect on neonatal screening test for congenital hypothyroidism.