Butanol-extractable iodine in human and bovine colostrum and milk.

High total iodine content and significant amounts of iodinated amino acids, but not of thyronines, have been reported in milk of various species. Since the human neonate requires thyroxine-like iodine compounds for central nervous system development, analyses of thyroxine-like iodine compounds such as butanol-extractable iodine of colostrum or early milk were indicated. Four samples of human milk 2-5 days postdelivery and 11 samples of bovine milk were examined for butanol-extractable iodine content. Thyroxine-like iodine compounds of colostrum or milk soon after parturition were extremely low, but total iodine values of milk supply abundant inorganic iodine for the mature neonatal thyroid.