The NHL's top-scoring defenseman left Wednesday night's 3-1 win over the New Jersey Devils in the third period after he was hauled down by Devils forward Steve Bernier.
General manager Brad Treliving says the team wants "to make sure we're being diligent in terms of the protocol on all of the medical side of things. Once we know where Mark's at, definitively, we'll share that."
Giordano has 11 goals and 37 assists in 61 games.
The Flames are trying to stay in the playoff mix during a seven-game road trip. Calgary ranked ninth in the Western Conference, tied in points with eighth-place Los Angeles, before Friday's game.