Effect of Iodine Loading on the Thyroid Hormone Level of Newborns Living in Kayseri Province

Abstract

Introduction Excessive iodine exposure during the fetal and neonatal periods can lead to neonatal hypothyroidism. This study was conducted to evaluate the level of iodine loading among newborns living in Kayseri province. A total of 59 newborns, who were admitted due to disorders in thyroid hormone levels, were included in the study.

Materials and Methods Among the patients who applied with thyroid hormone dysfunction, newborns with a spot urine iodine level ≥ 20 μg/dL were included in the study between the years 2003 and 2013. Free T3 (fT3), free T4 (fT4), thyroid stimulating hormone (TSH), thyroglobulin (Tg), breast milk iodine, thyroid ultrasonography, and control measurements of fT3, fT4, TSH, and Tg levels were obtained accordingly from both groups of patients who received or did not receive treatment.

Results The average age of the patients was 15 days with a 36/23 girl to boy ratio. Statistically, no significant difference was noticed between all the girls and boys with respect to all the measured values. The etiologic search showed that out of 59 cases, in 18 cases (30.5%) only the mother and in 19 cases only the newborns (32.2%) had a history of povidone iodine exposure; in 8 cases both mothers and their babies had exposure to povidone iodine (13.6%). In 14 cases (23.7%), the source of iodine loading could not be determined. Levothyroxine (L-thyroxine) treatment was initiated in 56% of the patients (n = 33). Out of 33 patients who were under treatment with L-thyroxine, in 13 cases only the mother had history of povidone iodine exposure; in 12 cases, only the baby had a history of povidone iodine exposure; in 1 case, both mother and her baby had a history of povidone iodine exposure, but the etiology could not be found in 7 cases.

Conclusion The use of antiseptics-containing iodine for mothers before and after birth and for newborns, especially for umbilical cleansing, can lead to iodine loading and hypothyroidism. If transient hypothyroidism develops within this period, then it may not be detected promptly. This can later lead to retardation in psychomotor development and disorder in learning skills during the childhood period.

Keywords

iodine - thyroid - newborn - thyroglobulin

• References

• 1 Kelly FC. Iodine in medicine and pharmacy since its discovery-1811-1961. Proc R Soc Med 1961; 54 (10) 831-836
• 2 McClure RD. Goiter prophylaxis with iodized salt. Science 1935; 82 (2129) 370-371
• 3 de Benoist B, McLean E, Andersson M, Rogers L. Iodine deficiency in 2007: global progress since 2003. Food Nutr Bull 2008; 29 (3) 195-202
• 4 Woeber KA. Iodine and thyroid disease. Med Clin North Am 1991; 75 (1) 169-178
• 5 Storm W. Transitorische Hypothyreose des Neugeborenen nach Amniofetographie mit jodhaltigem Kontrastmittel. Geburtshilfe Frauenheilkd 1986; 46 (3) 185-186
• 6 Eng PH, Cardona GR, Fang SL , et al. Escape from the acute Wolff-Chaikoff effect is associated with a decrease in thyroid sodium/iodide symporter messenger ribonucleic acid and protein. Endocrinology 1999; 140 (8) 3404-3410
• 7 Markou K, Georgopoulos N, Kyriazopoulou V, Vagenakis AG. Iodine-Induced hypothyroidism. Thyroid 2001; 11 (5) 501-510
• 8 Hudaoglu OG, Uçar SK, Atlihan F, Dizdarer C, Büyükgebiz A. The effects of topical iodine containing antiseptics on thyroidal status of preterm versus term babies. Saudi Med J 2009; 30 (6) 783-787
• 9 Furnée CA, van der Haar F, West CE, Hautvast JG. A critical appraisal of goiter assessment and the ratio of urinary iodine to creatinine for evaluating iodine status. Am J Clin Nutr 1994; 59 (6) 1415-1417
• 10 Kapelari K, Kirchlechner C, Högler W, Schweitzer K, Virgolini I, Moncayo R. Pediatric reference intervals for thyroid hormone levels from birth to adulthood: a retrospective study. BMC Endocr Disord 2008; 8: 15
• 11 Fisher DA. Hypothyroidism. Pediatr Rev 1994; 15 (6) 227-232 , quiz 232
• 12 Buchinger W, Lorenz-Wawschinek O, Semlitsch G , et al. Thyrotropin and thyroglobulin as an index of optimal iodine intake: correlation with iodine excretion of 39,913 euthyroid patients. Thyroid 1997; 7 (4) 593-597
• 13 Chanoine JP, Toppet V, Lagasse R, Spehl M, Delange F. Determination of thyroid volume by ultrasound from the neonatal period to late adolescence. Eur J Pediatr 1991; 150 (6) 395-399
• 14 Wolff J, Chaikoff IL , et al. The temporary nature of the inhibitory action of excess iodine on organic iodine synthesis in the normal thyroid. Endocrinology 1949; 45 (5) 504-513 , illust
• 15 Theodoropoulos T, Braverman LE, Vagenakis AG. Iodide-induced hypothyroidism: a potential hazard during perinatal life. Science 1979; 205 (4405) 502-503
• 16 Coakley JC, Francis I, Gold H, Mathur K, Connelly JF. Transient primary hypothyroidism in the newborn: experience of the Victorian Neonatal Thyroid Screening Programme. Aust Paediatr J 1989; 25 (1) 25-30
• 17 Nishiyama S, Mikeda T, Okada T, Nakamura K, Kotani T, Hishinuma A. Transient hypothyroidism or persistent hyperthyrotropinemia in neonates born to mothers with excessive iodine intake. Thyroid 2004; 14 (12) 1077-1083
• 18 Connelly KJ, Boston BA, Pearce EN , et al. Congenital hypothyroidism caused by excess prenatal maternal iodine ingestion. J Pediatr 2012; 161 (4) 760-762
• 19 Aliefendioğlu D, Sanli C, Cakmak M, Ağar A, Albayrak M, Evliyaoğlu O. Wolff-Chaikoff effect in a newborn: is it an overlooked problem?. J Pediatr Surg 2006; 41 (12) e1-e3
• 20 Khashu M, Chessex P, Chanoine JP. Iodine overload and severe hypothyroidism in a premature neonate. J Pediatr Surg 2005; 40 (2) E1-E4
• 21 Leger AF, Laurent MF, Savoie JC. Iodine excess and iatrogenic thyroid pathology (author's transl) [in French]. Ann Endocrinol (Paris) 1981; 42 (4-5) 446-453
• 22 Cassio A, Colli C, Piazzi S , et al. Results of screening of congenital hypothyroidism and iodine excess in neonatal age [in Italian]. Ann Ist Super Sanita 1998; 34 (3) 337-341
• 23 Bona G, Chiorboli E, Rapa A, Weber G, Vigone MC, Chiumello G. Measurement of urinary iodine excretion to reveal iodine excess in neonatal transient hypothyroidism. J Pediatr Endocrinol Metab 1998; 11 (6) 739-743
• 24 de Vijlder JJ, Ris-Stalpers C, Vulsma T. On the origin of circulating thyroglobulin. Eur J Endocrinol 1999; 140 (1) 7-8
• 25 Torréns JI, Burch HB. Serum thyroglobulin measurement. Utility in clinical practice. Endocrinol Metab Clin North Am 2001; 30 (2) 429-467
• 26 Knudsen N, Bülow I, Jørgensen T, Perrild H, Ovesen L, Laurberg P. Serum Tg—a sensitive marker of thyroid abnormalities and iodine deficiency in epidemiological studies. J Clin Endocrinol Metab 2001; 86 (8) 3599-3603
• 27 Zimmermann MB, Aeberli I, Andersson M , et al. Thyroglobulin is a sensitive measure of both deficient and excess iodine intakes in children and indicates no adverse effects on thyroid function in the UIC range of 100-299 μg/L: a UNICEF/ICCIDD study group report. J Clin Endocrinol Metab 2013; 98 (3) 1271-1280
• 28 WHO/UNICEF/ICCIDD.. Assessment of Iodine Deficiency Disorders and Monitoring Their Elimination: a Guide for Programme Managers. 3rd ed. Geneva, Switzerland: World Health Organization; 2007