Iodine in Contrast Agents and Skin Disinfectants Is the Major Cause for Hypothyroidism in Premature Infants during Intensive Care

Abstract

In 51 sick newborns the influence of two different nonionic, iodine-containing contrast agents, Amipaque® (group 1) and Omnipaque® (group 2) and of long-term treatment with polyvinylpyrrolidone-iodine (PVP-I) (group 3) on thyroid function was studied. In the dose given, freshly dissolved Amipaque® releases roughly 100 µg ‘free’ iodide/kg body weight; this release may be even higher in the solubilized agent Omnipaque® because of increased breakdown. Urinary iodine excretion was elevated in all groups on day 5 after iodine exposure. In group 1 which included 17 term newborns, the median TSH level was normal after 5 days and 2 weeks, only 1 case of transient hypothyrotropinemia was observed; T₄ and T₃ median levels were in the lower range of normal. In groups 2 and 3, which included 8 preterm infants of 15 newborns and 9 preterm infants of 19 newborns, respectively, the median TSH values were elevated and T₄ and T₃ levels were very low. Hypothyroidism was diagnosed in 6 of the 8 preterm and in 1 of the 7 term newborns of group 2. In group 3, 7 of the 9 preterm and 3 of the 10 term newborns reacted with hypothyroidism. Eight preterm and 3 term newborns had to be substituted with thyroxine. The thyroid function of term newborns was less affected by Amipaque® or Omnipaque® than by PVP-I. The data show that preterm infants are very sensitive to an iodine load.

Parenteral trace element provision: recent clinical research and practical conclusions

“…104 Furthermore, PN patients are frequently exposed to iodine from various exogenous sources, in particular from iodine-based skin antiseptics. 105, 106 Non-dietary iodine provision has been considered adequate to meet basal requirements as thyroid function remains normal in the majority of long-term PN patients, 11 and there are no reports of iodine deficiency symptoms during hospital PN. 37 As the wide replacement of iodine-containing antiseptics with 2% chlorhexidine for skin cleansing, the risk of iodine deficiency in patients receiving PN has increased during recent years.…”

Iodine Supplementation: Usage “with a Grain of Salt”

“…Thereby neonatal goiter and congenital hypothyroidism can occur in case of maternal excessive iodine intake [ 36 , 37 ]. Moreover, cases of acquired neonatal hypothyroidism due to iodine overload have been observed in preterm infants [ 38 ], full-term infants with congenital heart disease [ 39 ], and infants exposed to iodine-containing antiseptics during delivery [ 40 ] and during breastfeeding [ 41 ].…”