Tsunade did tell them to make researching "that effect" their top priority. Naturally, they'd report those results to her before moving onto other things. (plus, didn't Shizune say the autopsy wasn't complete?)Originally Posted by Darth Ender
For most of Shippuuden, Tsunade's focus was to protect Naruto. It makes sense to research any self harm he's doing to himself before working out how a dead enemy's (unique) ability works. This is true especially for Tsunade, who had two close ones die on her.