Pregnancy iodine

Iodine Deficiency in Pregnancy Iodine Deficiency and Supplementation in Pregnancy... 

In the cerebral hemispheres, there was little change in weight or cell number (as measured by the DNA content) but in the visual cortex area an increase in neuronal density was apparent in the granular band in the second pregnancy iodine-deficient newborns. Synaptic counts also were reduced in the visual cortex (Table 2). 

A deficiency of iodine results iu insufficient synthesis of thyroxine and a low plasma level, so that secretion of TSH is increased in an attempt to stimulate synthesis but this results in enlargement of the thyroid gland (goitre). Iodine deficiency in pregnancy impairs brain development in the foetus, causing mental retardation (known as cretinism). Indeed iodine deficiency is one of the major public health issues worldwide an estimated 200 million people are affected. 

Iodides should not be used alone since the normal gland will escape from iodide blockade in 2-8 weeks. Chronic use in pregnancy is not recommended because it crosses placenta and cause fetal goitre. Iodide treatment results in high intrathyroidal iodide content that can delay the onset of thioamide therapy or delay the use for radioactive iodine therapy for weeks if not months. Adverse effects include Hodism which is rare and reversible. The clinical symptoms are acneiform rash, sialadenitis, mucous membrane ulceration, conjuctivitis, rhinor-rhoea, metallic taste and rarely anaphylactoid reaction. 

WHO/UNICEF/ICCIDD. Iodized oil during pregnancy. Safe use of iodized oil to prevent iodine deficiency in pregnant women. Geneva (Switzerland) World Health Organization 1996. (WHO/NUT/96.5). 

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]... 

Neonatal goiter caused by the use of potassium iodine as an expectorant during pregnancy has been reported (67). The neonate, a girl, had acute hypothyroidism, with myxedema and respiratory distress. She was given levothyroxine for 6 months, with complete normalization of thyroid function. 

Severe transient postnatal hypothyroidism has been reported in infants whose mothers have received high doses of iodine during pregnancy or multiple local applications of povidone-iodine during pregnancy and for delivery (SED-14, 472). Transient neonatal hypothyroidism during breastfeeding after postnatal maternal topical iodine treatment has also been reported (68). 

Skin disinfection with iodine also caused goiter and hypothyroidism in five of 30 newborns under intensive care (69). Antiseptics containing iodine should be avoided not only during pregnancy and delivery but also after the delivery during breastfeeding. 

Radioactive iodine passes the placenta and accumulates in the fetal thyroid where the concentration probably exceeds that in the maternal thyroid. Detailed studies show that the fetal dose of iodine is virtually nil before the 90th day of gestation but sharply increases thereafter (29). This alone is sufficient reason to avoid the use of 131I in pregnancy, but there is also some controversial evidence that various congenital deformities have been produced by the isotope (30). 

Goh KO. Radioiodine treatment during pregnancy chromosomal aberrations and cretinism associated with maternal iodine-131 treatment. J Am Med Womens Assoc 1981 36(8) 262-5. 

Iodine concentrations in breast milk and in random urine in neonates and the serum concentrations of neonatal TSH and free thyroxine on day 5 after delivery were measured after the use of povidone-iodine for disinfection after delivery (36). Iodine concentrations in the breast milk and neonatal TSH were significantly raised. Perinatal iodine exposure causes transient hypothyroidism in a significant number of neonates, in whom careful monitoring and follow-up of thyroid gland function are needed. It is better to avoid the use of iodine-containing antiseptics in pregnancy and neonates, especially if follow-up cannot be guaranteed. 

Mahillon I, Peers W, Bourdoux P, Ermans AM, Delange F. Effect of vaginal douching with povidone-iodine during early pregnancy on the iodine supply to mother and fetus. Biol Neonate 1989 56(4) 210-7. 

Because ICG contains a small amount of sodium iodide, it should not be used in patients with sensitivities to iodine or shellfish or in patients at high risk for anaphylactic reaction. The safety of this agent in pregnancy has not been established. 

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