“Maternal/Neonatal” Iodine Status in Patients with Prolonged Physiological Jaundice

Abstract

Background: The increasing knowledge indicated that borderline hypothyroidism may cause neurodevelopmental disorders. Borderline compensated congenital hypothyroidism could caused by iodine deficiency or iodine overload. One of the most important etiological factors causing prolonged jaundice in the neonatal period is congenital hypothyroidism. Aimed of this study is to investigate the frequency of borderline or overt hypothyroidism in a group of newborn with prolonged physiological jaundice, and to evaluate iodine status of these babies and their mothers.

Methods: Fifty-five apparently healthy newborn were evaluated. Twenty-five of them showed borderline thyroid dysfunctions. Remained 30 babies had normal thyroid function, considered as euthyroid group. Iodine status was evaluated by measuring urinary iodine excretion.

Results: According to UIE, maternal iodine deficiency (55%) associated with neonatal iodine overload (65%) had came to attention. Although mean urinary iodine levels in both mother groups were similar, the mean urinary levels of borderline hypothyroidic and euthyroid groups were 432±129 μg/l and 271.5±137 μg/l, respectively. Iodine overload was also presence in newborn with normal thyroid function tests.

Conclusion: We considered that individual sensitivity to iodine overload could make the differentiation on thyroid function. Iodine overload in important degree seen in borderline hypothyroidic babies emphasize the harmful effect of topical antiseptic iodine application that given to mothers during labor. This application could also mask possible prenatal iodine deficiency.

Key words

borderline hypothyroidism - iodine deficiency - iodine overload

References

• 1 Alemzadeh R, Friedman S, Fort P. et al . Is there compensated hypothyroidism in infancy?.  Pediatrics. 1992;  90 207-211
• 2 Calaciura F, Mendorla G, Distefano M. et al . Childhood IQ measurement in infants with transient congenital hypothyroidism.  Clin Endocrinol. 1995;  43 473-477
• 3 Calaciuria F, Motta RM, Miscio G. et al . Sub clinical hypothyroidism in early childhood: a frequent outcome of transient neonatal hyperthyrotropinemia.  J Clin Endocrinol Metab. 2002;  87 3209-3214
• 4 Daliva AL, Linder B, DiMartino-Nardi J. et al . Three-year follow-up of borderline congenital hypothyroidism.  J Pediatr. 2000;  136 53-56
• 5 Dunn JT, Crutchfield HE, Gutekunst R. et al . Two simple methods for measuring iodine in urine.  Thyroid. 1993;  3 119-123
• 6 Erdoğan G, Erdogğan MF, Emral R. et al . Iodine status and goiter prevalence in Turkey before mandatory iodization.  J Endocrinol Invest. 2002;  25 224-228
• 7 Gaudino R, Gerelt C, Czernichow P. et al . Proportion of various types of thyroid disorders among newborns with congenital hypothyroidism and normally located gland.  Clin Endocrinol. 2005;  62 444-448
• 8 Hannam S, MacDonnel M, Rennie JM. Investigation of prolonged neonatal jaundice.  Acta Pediatr. 2000;  89 694-697
• 9 Kabyemala EAR, Swinkels LMJW, Chuwa LMM. et al . Thyroid function studies in normal pregnant Tanzanian women.  Am J Trop Med Hyg. 1996;  54 58-61
• 10 Kung AWC, Lao TT, Chau MT. et al . Goitrogenesis during pregnancy and neonatal hypothyroxinaemia in a borderline iodine sufficient area.  Clin Endocrinol. 2000;  53 725-731
• 11 Kung AWC, Pang RWC, Janus ED. Elevated serum lipoprotein (a) in sub clinical hypothyroidism.  Clin Endocrinol. 1995;  43 445-449
• 12 Kurtogğlu S, Akçakuş M, Kocaogğlu Ç. et al . Iodine status remains critical in mother and infant in central Anatolia (Kayseri) of Turkey.  Eur J Nutr. 2004;  43 297-303
• 13 L’Allemand D, Gruters A, Heidman P. et al . Iodine-induced alterations of thyroid function in newborn infants after prenatal and perinatal exposure to povidone iodine.  J Pediatr. 1983;  102 935-938
• 14 Linder N, Davidovitch N, Reichman B. et al . Topical iodine-containing antiseptics and sub clinical hypothyroidism in preterm infants.  J Pediatr. 1997;  131 434-439
• 15 MacElduff A, MacElduff P, Wiley V. et al . Neonatal thyrotropin as measured in a congenital hypothyroidism screening program: influence of the mode of delivery.  J Clin Endocrinol Metab. 2005;  90 ((12)) 6361-6363
• 16 Nishiyama S. Transient hypothyroidism or persistent hyperthyrotropinemia in neonates born to mothers with excessive iodine intake.  Thyroid. 2004;  14 1077-1083
• 17 Nøhr S, Laurberg P. Opposite variations in maternal and neonatal thyroid function induced by iodine supplementation during pregnancy.  J Clin Endocrinol Metab. 2000;  85 623-627
• 18 Oltarzewski M, Szymborski J. Neonatal hypothyroid screening in monitoring iodine deficiency and iodine supplementation.  J Endocrinol Invest. 2003;  26 27-31
• 19 Rapaport R. Congenital hypothyroidism: expanding the spectrum.  J Pediatr. 2000;  136 10-12
• 20 Rendl J, Bier D, Groh T, Reiners C. Rapid Urinary Iodide Test.  J Clin Endocrinol Metab. 1998;  83 1007-1012
• 21 Turan S, Bereket A, Angaji M. et al . The effect of the mode of delivery on neonatal thyroid function.  J Matern Fetal Neonatal Med. 2007;  20 ((6)) 473-476
• 22 World Health Organization, United Nations Children's Fund, International Council for Control of Iodine Deficiency Disorders . Assessment of the iodine deficiency disorders and monitoring their elimination. Geneva: World Health Organization 2001 WHO document WHO/NHD/01.1

Correspondence