Sentence:  In the presence of a low iodine intake , thyroglobulin labelled in vivo with * * f is found to contain more mono-iodotyrosine than normal , the amounts of <WSD>di-iodotyrosine</WSD> and iodothyronines being correspondingly reduced . 
Meaning of the word marked with <WSD> tags:  tyrosine with two iodine atoms added