Postma is scoreless in eight games this season with the Jets, playing most recently Saturday in a 2-1 shootout win against the Dallas Stars. He skated 18 shifts for 15:10 of ice time and had three blocked shots.
"I had an awkward pain in my calf," Postma told reporters Monday. "It didn't feel right. There was part of me that didn't know why it was hurting so much. I talked to our trainers about it and went and got it checked out, and it turned out to be a blood clot."
Postma said his leg started bothering him a few days earlier and worsened following the game against Dallas when the Jets traveled to Colorado for the game Sunday against the Avalanche. He said he was told it could be several months before he's able to return.
"I don't really know much about blood clots. You don't really hear about them too often," he said. "When [the doctor] told me the timeline that they were thinking of, it really startled me and I was in shock. I can't really believe it happened."
Postma became an NHL regular with the Jets during the 2012-13 season and scored four goals with five assists in 34 games. The diagnosis was difficult on him, not only in terms of his health but what will now be a prolonged absence from the Winnipeg lineup.
"That's hard to hear. I've never been out with an injury that long, not even close," he said. "It's going to be tough for me, but just stay positive and try to get through it."