Last update Nov. 23, 2019
Very Low Risk
Hypothyroid infants may have feeding difficulties due to sucking and swallowing problems due to neurological retardation and macroglossia (large tongue) (Lawrence 2016 p 498). Because of this and difficulty in gaining weight, they are more at risk of having breastfeeding suspended.
Breastfeeding is the best option for a hypothyroid infant (Lawrence 2016 p 498, Lawrence 2013).
Although breastmilk has significant amounts of thyroid hormone (Sack 1979 and 1977, Varma 1978) and breastfed infants have higher plasma concentrations of thyroid hormones than non-breastfed infants (Hahn 1983), breastmilk is not sufficient on its own to treat hypothyroidism (Sack 1979, Varma 1978).
The treatment consists in the daily oral administration of synthetic thyroid hormone, levothyroxine (LT4), either in the form of crushed tablets or the new liquid forms.
The intestinal absorption of the thyroid hormone decreases discreetly with the calcium in the milk (Chon 2018) so it is usually recommended that it be administered whilst fasting, half an hour before eating (Bach 2009).
But this recommendation is not applicable to small breastfed infants. Keep in mind that cow's milk, on which the 2018 Chon article is based, contains 1,300 mg/L of calcium versus 330 mg/L in breastmilk.
In addition, the amount of LT4 to be administered depends on the analytical results of the infant, increasing or decreasing the dose depending on the TSH and T4 results of the infant.
Several medical associations, experts and expert consensus in pediatric endocrinology recommend mixing LT4 with water or "breastmilk" for administration (Castilla 2015, Lèger 2014, GPC 2014, Brown 2012, Grob 2012).
The bioavailability of LT4 liquid preparations does not decrease with the simultaneous intake of food, so it would not be necessary to carry out a period of fasting with this type of preparations (Pirola 2018, Marina 2017, Ianiro 2014, Bernareggi 2013).
Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it.
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