Increased recall rate at screening for congenital hypothyroidism in breast fed infants born to iodine overloaded mothers.

Abstract

SUMMARY Skin disinfection with povidine-iodine (PVP-I) is widely used in obstetrics. We evaluated the influence of PVP-I in mothers at delivery on the serum thyroid stimulating hormone concentrations of their infants at the time of screening for congenital hypothyroidism. The study covered 4745 infants who were either breast fed (3659, 77%) or bottle fed (1086, 23%); 3086 (65%) of them were born to mothers with no iodine overload (controls) and 1659 (35%) to mothers with iodine overload. Compared with the control group, the breast and bottle fed infants born to mothers with iodide overload had a shift of neonatal thyroid stimulating hormone concentration towards high values. The shift was maximal in the breast fed infants with a 25 to 30 fold increase in the recall rate at screening for congenital hypothyroidism (serum thyroid stimulating hormone >50 mU/l) while in the bottle fed infants, the recall rate was barely modified. In conclusion, the use of PVP-I in mothers at delivery induces a transient impairment of thyroid function in their infants, especially if breast fed. This situation is detrimental to screening for congenital hypothyroidism. Consequently PVP-I is not recommended in obstetrics.Skin disinfection with povidone-iodine (PVP-I) is widely used in obstetrics in epidural anaesthesia or caesarean section. This procedure results in iodide overload of the mother due to cutaneous absorption of iodine. 1 Iodide readily crosses the placenta2 and is actively concentrated in the mammary gland.3 Consequently, newborn infants born to mothers treated with PVP-I are also exposed to iodine overload, especially if breast fed.4The thyroid gland of newborns is highly sensitive to the blocking effect of excess iodide on thyroid hormone synthesis, and a raised concentration of serum thyroid stimulating hormone is the most reliable index of impairment of thyroid function.5The objective of the present work was to evaluate the influence of cutaneous application of PVP-I in mothers at delivery on the concentrations of thyroid stimulating hormone in their infants at the time of screening for congenital hypothyroidism. In order to appreciate the specific role of the iodine contained in breast milk, a comparative study was performed between breast and bottle fed infants. Patients and methodsThe study included 4745 (96%) of the 4923 infants born in our maternity ward during a two year period. Of the 178 infants who were not included in the study, three were omitted because they had permanent congenital hypothyroidism due to thyroid agenesis with an appreciably raised serum thyroid stimulating hormone concentration and a low thyroxine concentration at screening and diagnosis. One hundred and seventy five (45 full term and 130 premature infants) were omitted because they were neither breast nor bottle fed: they were severely ill and received total parenteral nutrition until at least the fifth day of life. None of these 175 infants had a serum thyroid stimulating hormone concentration >50 mU/l at the time of screening for congeni...

Rate of Recalls in Congenital Hypothyroidism Based upon a Regional Survey in Isfahan, Iran, Using Serum T4 and TSH Analyses: Comparison of Two Different Recall Methods

“…The results showed that the rate of recall was significantly increased among deliveries using povidone iodine and also among neonates who were breast-fed [13]. According to the announcement of the Isfahan CH screening project committee, maternity hospitals were advised not to use povidone iodine as far as possible during the course of delivery, but it cannot be ascertained that this recommendation has been accepted and implemented carefully.…”

“…Different surveys have been implemented to study recalls and factors affecting recall rate in CH screening programs [2,10,11,12,13,14,15]. The different recall rates in various screening programs are suggested to be due to several factors [1]: the use of T4 or TSH level or both for screening [2], differences in sample collecting methods and laboratories [3,] different established criteria for recalling that is related to cultural, regional, and social factors of a community.…”

Thyroid Dysfunction in Neonates Born to Mothers Who Have Undergone Hysterosalpingography Involving an Oil-Soluble Iodinated Contrast Medium

“…Excessive maternal iodine intake is one of the well-known causes of neonatal transient hypothyroidism or hyperthyrotopinemia [1,2,3,4,5,6]. Excessive maternal iodine intake may arise due to the consumption of iodine-rich foods, such as seaweed, and iodine-containing medicines.…”

Thyroid Function in Nurses: The Influence of Povidone-Iodine Hand Washing and Gargling

“…The amount of iodine incorporated after gargling using PVP-I cannot be neglected. Therefore, long-term use of PVP-I for gargling should be avoided in people with a high risk of developing thyroid dysfunction due to excessive intake of iodine, such as those with existing thyroid disease [1, 6, 11, 12], and in pregnant women [12, 13, 14] and breast-feeding mothers [15], because of possible effects on the thyroid function of their babies.…”