Per the team, no further details will be shared.
Hedman, 35, last played March 19 against the Vancouver Canucks, where he exited early due to an illness.
In 33 games this season — shortened as a result of injuries — the Swede has one goal and 17 points.
The 2009 second-overall pick has played 1,164 NHL games, all with Tampa Bay.
The Lightning return to action Thursday against the Seattle Kraken.
