Bolton saw skipper David Wheater forced off early in the second half with a back problem before Josh Vela was carried off on a stretcher in the closing stages with a serious ankle injury.
Christiansen added: “Berardi’s injury was his shoulder and Matthew Pennington’s was his ankle.
“We will know more in the next couple of days. It’s disappointing, but at the same time I was very pleased with the contribution of Conor Shaughnessy and Vurnon Anita.
“They came on and did well, so there were negatives and positives and overall I enjoyed it a lot.
“It was a tough game, which I expected, against a tough opponent, and a result I had dreamed of.
“We need to recover now and focus on Port Vale in the League Cup on Wednesday.
“It’s good to start the season like this and now we have a few games at Elland Road where we will have even greater backing from our supporters.”
Manchester United left-back Cameron Borthwick-Jackson is poised to join Leeds on loan and at least one more centre-back is also on Christiansen’s radar.
The Dane left out Liam Bridcutt, Stuart Dallas and Ronaldo Vieira – all regulars last season – and he explained: “These are the problems I have as coach.
“It’s good that I have to choose, but bad that I have to leave players out. Only 18 players can play and today I’m happy with the decision I took.”
Wood hit 30 goals last season and continues to be linked with a number of rival clubs, but Christiansen said: “It’s very important to keep Chris Wood, but you never know what will happen.”
Bolton boss Phil Parkinson bemoaned his side’s injury blows and defensive frailties as they lost their first game back in the Championship after one season in League One.
Parkinson said: “The worry for us is that Wheater had to come off with a problem he had in the week during training.
“Josh looks like he’s going to go to hospital and we need to keep our fingers crossed in the next 24 hours that it’s not too bad.
“But when Josh Vela went down and stayed down, I was instantly worried because he’s a tough lad and he very rarely goes down.
“We conceded some uncharacteristic goals when you consider the defensive qualities we showed last year.
“But in the second half we showed a good reaction, especially when you’re 3-1 down in the first game of the season in front of the TV cameras.
“I thought we gave it everything to try and get back in the game. We got it back to 3-2 and nearly got something from it.”