Neonates iodine requirements

Delange F Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition. Public Health Nutr 2007 10 1571. [PMID 18053281]... 

Iodide requirements in extreme preterm infants are particularly difficult to assess as they have very limited thyroidal iodine reserves (Etling, 1977 Costa et ai, 1986 van den Hove et at, 1999), and they are also susceptible to iodine toxicity and hypothyroidism if too much iodide is given (L AUemand et ai, 1987). There are no current pubhshed studies indicating the iodine requirements of extreme preterm infants, sick infants, or infants in the early neonatal period. Iodide requirements of these infants should therefore be assessed through carefully-controlled studies that avoid toxicity, but also test the efficacy of iodide supplementation in optimizing thyroid function. 

The risk of excessive iodine intake in sheep is high if mineral blocks are used for supplementation. When the effects of the major and trace elements in the amounts administered via the mineral blocks were assessed separately, only iodine reduced plasma immunoglobulin (Ig)G concentration (Boland etaL, 2004). Rose etal. (2007) fedlactating ewes 5.5, 9.9, 14.8 and 21 mg-iodine/kg-diet dry matter. The lambs of the mothers given the two highest iodine doses had only half the IgG in the plasma of those born to mothers fed the lowest dose (Rose et al., 2007). Absorption of sufficient Ig from the mother is required to maintain the health of the mammalian neonate. A deficiency of Ig in the neonate increases the incidence of pneumonia, septicemia and navel infections, increasing neonatal mortality. 

Iodine is readily absorbed when PVP-I is applied to the skin of a newborn infant, because of high cutaneous permeability, and neonates are very sensitive to iodine overload, as described previously. Topical PVP-I therapy is associated with a significant risk of hypothyroidism in neonates, especially very-low-weight babies (Smerdely et ai, 1989). Many cases of hypothyroidism induced by topical use of PVP-I have been reported in newborn infants, mainly from iodine-deficient regions (Markou et ai, 2001). However, a case of severe hypothyroidism in a neonate was also reported from North America, an iodine-sufficient region (Khashu et al. 2005). A premature infant developed severe hypothyroidism that required L-thyroxine replacement therapy after application of PVP-I for 20 days. 

Figure 108.1 Human fetal and neonatal hypothyroid syndromes iodine defioienoy and endemic cretinism. If environmental iodine deoreases, maternal iodine deficiency in early pregnancy will not provide the fetal thyroxine required for neural development. Insuffioient supply of iodine leads to fetal and neonatal hypothyroidism.

Administration usually creates pain, anxiety and phobia, and requires professionally trained staff. Topical anaesthesia (creams, gels, patches or simply cold to numb the area) is usually performed to help to manage the pain and associated fears, as well as to distract the child. There is no taste issue with the parenteral routes but the excipients used must be biodegradable imder the available metabolic processes. This can be a problem in neonates as not all pathways have fully matured. Moreover, formulation composition is critical as some excipients can be toxic. This includes vehicles, preservatives or even the antiseptic used to disinfect the surface of the skin prior to injection (e.g. iodine-containing antiseptic that can be absorbed through the skin). 

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