Worthington's side are set to face San Marino on Wednesday in a 2010 World Cup qualifier.
Their preparations had been hindered by the withdrawal of Manchester United centre-half Jonny Evans through injury and Fulham full-back Chris Baird through illness.
Worthington has, therefore, decided to add Cathcart to his senior party as cover.
The 20-year-old, who is currently on loan at Plymouth from Manchester United, was initially scheduled to play for Northern Ireland's U21 side in a friendly against Wales on Tuesday.
Under-21 manager Steve Beaglehole believes Cathcart will not let anyone down if he is given a chance to impress.
"I am pleased for Craig," he said. "I have also seen him in action a couple of times for Plymouth and he has made big strides.
"Craig is a good footballer, you can see why Manchester United signed him. He is comfortable on the ball and reads the game well. He just lacks a bit of physical strength at the moment."