The 20-year-old is one of nine players drafted in by manager Chris Coleman after a series of withdrawals over the weekend.
Isgrove will link up with Wales shortly ahead of their final two 2014 FIFA World Cup qualifiers, the first of which sees them host Macedonia on Friday at the Cardiff City Stadium.
The squad then travels over to Brussels, where they face Belgium in the King Baudouin Stadium on Tuesday night.
Wales currently sit bottom of UEFA Qualifying Group A with no chance of reaching next summer's World Cup finals in Brazil, so Coleman may well see the game as an opportunity to blood some youngsters.
Isgrove joins Artur Boruc (Poland), Maya Yoshida (Japan), Dejan Lovren (Croatia), Rickie Lambert (England), Steven Davis (Northern Ireland), Gastón Ramírez (Uruguay), Dani Osvaldo (Italy) James Ward-Prowse, Luke Shaw (both England Under-21s), Calum Chambers, Matt Targett (both England Under-19s) and Chris Johns (Northern Ireland Under-19s) in departing for international duty this week.