GetInventoryInfoByItemID API Documentation

-- Returns details about which not hidden characters and guilds contain items matching the item ID
-- (does not work for battle pet cages).
--   itemID: number
--   onlyConnectedRealms: boolean
--   onlyCurrentFaction: boolean
Syndicator.API.GetInventoryInfoByItemID(itemID, onlyConnectedRealms, onlyCurrentFaction)

See here for some sample output.