November 1983

Thyroid Function and Human Breast Milk

Author Affiliations

Obstetrics and Gynecology Research Laboratory Albert Einstein Medical Center/Northern Division Philadelphia, PA 19141

Am J Dis Child. 1983;137(11):1131. doi:10.1001/archpedi.1983.02140370087034

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Sir.—I am writing with regard to the article "Thyroid Function Tests in Neonates Fed Human Milk" by Hahn et al (Journal 1983;137:220-222). Relevant to the data presented in that article are the findings of myself and Alfred Tenore, MD, that were recently published in Hormone Research (1983; 17:11-18). We have demonstrated the presence of at least physiologic levels of triiodothyronine (T3) in human milk of all full-term mothers examined, but we have found low to undetectable thyroxine (T4) concentrations. This study coupled column chromatography with specific T3 and T4 radioimmunoassays, enabling a highly sensitive and specific assessment of the hormonal content of the milk samples that were tested. Most breast milk thyroid hormone studies have focused on T4 content and the apparent inability of milk ingestion to affect T4 levels in screening for congenital hypothyroidism; however, the role of T3 in breast