Is Iodine safe while breastfeeding?

Effects on the breastfed infant

In Switzerland, a girl born at 29 weeks of gestation with adequate size for gestational age showed negative TSH screening on day 5. Her mother developed an abscess of the abdominal wall 1 week after her cesarian section and the wound was packed with tampons containing about 10.5 mg of iodine. The baby's TSH was elevated to 23 milliunits/L on day 23, and 288 milliunits/L on day 29. Free thyroxine (T4) levels were decreased to 2.8 ng/L and free liothyronine (T3) with 1.52 ng/L, without signs or symptoms of hypothyroidism. Iodine contents of maternal milk and of infant urine were 4.4 mg/L and 3.9 mg/L, respectively. Treatment with levothyroxine was started, breastfeeding was discontinued and disinfection with iodine was stopped. The infant's thyroid function tests normalized after 6 days.[ 44 ] The infant's abnormal thyroid function tests were probably caused by maternal iodine use. The mother of a 31-week, 961 gram preterm infant packed her cesarean section wound with iodine-soaked gauze because of wound dehiscence and infection. She was expressing milk for her hospitalized infant. The infant's thyroid function tests were normal at birth, but at 2 weeks of age, the infant's serum thyroxine was borderline low and TSH levels were elevated. One week later, TSH had increased to 77 milliunits/L and both thyroxine and free thyroxine levels were low. Breastmilk was discontinued and levothyroxine was started. The mother discontinued the iodine packing and 1 week later breastmilk feeding was resumed. At 2 months of age, the infant's thyroid function test were normal while taking levothyroxine.[ 45 ] A study of 31 preterm infants born at 34 weeks gestational age or less was performed in Korea where mothers typically ingest large amounts of seaweed soup during the first month postpartum. Subclinical hypothyroidism was frequently found in the infants with high intake of iodine from breastmilk.[ 17 ] A mother used an iodine antiseptic on her episiotomy wound for 10 to 12 days post

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Iodine is a normal mineral in breastmilk that is essential for the infant's thyroid. Iodine concentrations are highest in colostrum, declining gradually as lactation progresses. The amounts of iodine in breastmilk vary with maternal iodine intake and possibly with genetic variants in the NaI symporter and its activity may be increased by breastfeeding.[ 25 , 26 ] The WHO recommends that lactating women have urinary iodine levels of 100 mcg/L. Others have suggested a breastmilk iodine reference range between 60 and 450 mcg/kg.[ 9 ] Maternal Levels. Usual dietary intake. A study in Thailand compared mothers supplemented with 200 mcg daily of iodine daily to unsupplemented mothers. Breast milk samples were collected from 57 lactating women, 33 of whom received iodine supplementation during pregnancy. The median breastmilk iodine concentration at 2 months postpartum was significantly higher in the supplemented mothers (109 mcg/L) than in unsupplemented mothers 70 mcg/L).[ 27 ] A study of 97 iodine-sufficient women in Switzerland compared two analytic methods. The ICP-MS standard curve method found a median iodine concentration of 245 mcg/kg in pooled milk samples from 25 women while the ICP-MS 129-I isotope ratio method found a median concentration of 183 mcg/kg in pooled milk samples of 66 women.[ 28 ] A study of 36 breastmilk samples from 18 different states in 2003 to 2004 found a mean iodide breastmilk concentrations of 63.3 mcg/L (range 4.5 to 162 mcg/L).[ 29 ] Another study of 108 breastmilk samples from 10 women by the same authors found a mean iodide concentration of 87.9 mcg/L (range 3.1-334 mcg/L), and a median concentration of 55.2 mcg/L.[ 30 ] The reason for the differences in iodine values between these two studies and the above studies is not clear. A study in northern Spain compared the milk iodide level of mothers taking a normal diet, including iodized salt and seafood (n = 14), with mothers on the same diet plus a supplement of 200 mg daily of potassiu

Alternatives LactMed lists

• Benzalkonium Chloride