The amount of a 3,3',5-triiodo-L-thyronine when measured in anatomical entity. The trait is 3,3',5-triiodo-L-thyronine level (OBA_1000960, an Ontology of Biological Attributes term). Also known as: 3,3',5-triiodo-L-thyronine amount, anatomical entity 3,3',5-triiodo-L-thyronine amount, thyroid hormone T3 amount, thyroid hormone T3 level, triiodothyronine amount, triiodothyronine level.