“…Therefore, thyroxine present in the faeces of the orally treated rats could not be entirely due to failure of absorption; interpretation of the results is further complicated by the fact that some at least of the thyroxine and its metabolites excreted in the bile would be re-absorbed from the intestinal lumen (cf. Schittenhelm & Eisler, 1932;Gross & Leblond, 1947). Our results indicate that about 70 % of an oral dose of sodium DL-thyroxine is absorbed by rats.…”