| Member | Definition | Role |
|---|
| 2-iodophenol | | 2-iodophenol |
| 4-iodophenol | | 4-iodophenol |
| ioxynil | A nitrile that is benzonitrile substituted by a hydroxy group at position 4 and iodo groups at positions 3 and 5. | ioxynil |
| tetraiodothyroacetic acid | A monocarboxylic acid that is thyroacetic acid carrying four iodo substituents at positions 3, 3', 5 and 5'. | 3,3',5,5'-tetraiodothyroacetic acid |
| thyroxine | An iodothyronine compound having iodo substituents at the 3-, 3'-, 5- and 5'-positions. | thyroxine zwitterion; thyroxine |
| thyroxine | The L-enantiomer of thyroxine. | L-thyroxine zwitterion; L-thyroxine |
| triiodothyronine | An iodothyronine compound having iodo substituents at the 3-, 3'- and 5-positions. Although some is produced in the thyroid, most of the 3,3',5-triiodo-L-thyronine in the body is generated by mono-deiodination of L-thyroxine in the peripheral tissues. Its metabolic activity is about 3 to 5 times that of L-thyroxine. The sodium salt is used in the treatment of hypothyroidism. | 3,3',5-triiodo-L-thyronine zwitterion; 3,3',5-triiodo-L-thyronine |