An athyrotic infant had hypothyroidism at 1 year of age. He had grown at an above-average velocity until age 10 months when breast-feeding was discontinued, yet his bone age remained that of a newborn. These observations suggested that breast-feeding had attenuated hypothyroidism by providing significant quantities of thyroid hormones in the milk. To test this hypothesis, thyroxine (T4), 3,5,3'- triiodothyronine (T3, and 3,3',5'-triiodothyronine (reverse T3) were measured in breast milk samples collected serially from three months before to four months after delivery. Mean breast milk T4 content fell from 1.4 to 0.7 μg/dl within 48 hours after delivery, while T3 content rose from 136 to 286 ng/dl. Reverse T3 content remained unchanged. The shift in the T4/T3 ratio after delivery was observed in samples of all five donors; the highest postpartum T4 level was 1.1μg/dl and the highest postpartum T3 level was 405 ng/dl. It is concluded that breast-feeding may deliver sufficient thyroid hormones to the athyrotic infant to mitigate severe hypothyroidism and to prevent impaired neurological development.
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机译：一名无甲状腺的婴儿在1岁时患有甲状腺功能减退症。他的成长速度高于平均水平，直到停止母乳喂养的10个月大时为止，但他的骨龄仍然是新生儿的年龄。这些观察结果表明，母乳喂养可通过在牛奶中提供大量甲状腺激素来减轻甲状腺功能减退症。为了检验该假设，从三个月前至四个月连续收集的母乳样品中测量了甲状腺素（T4），3,5,3'-三碘甲状腺素（T3和3,3'，5'-三碘甲状腺素（反向T3）分娩后48小时内母乳中的T4平均含量从1.4降至0.7μg/ dl，而T3含量从136 ng / dl上升至286 ng / dl。反向T3含量保持不变。分娩后T4 / T3比值的变化在所有五个供体的样本中均观察到了这种现象;最高的产后T4水平为1.1μg/ dl，最高的产后T3水平为405 ng / dl。结论是，母乳喂养可为无足轻症婴儿提供足够的甲状腺激素，以减轻重症婴儿的体质甲状腺功能减退并防止神经系统发育受损。
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