Castillo, 31, entered Wednesday’s action batting .270/.314/.477 with six home runs and 15 RBI in 118 plate appearances. He has gotten the bulk of the work behind the plate, backed up by Omar Narváez.
Castillo’s absence will likely prompt the White Sox to call up Kevan Smith from Triple-A Charlotte. Smith battled an ankle injury in March and April, so he got a late start to the season. In 102 PA at Triple-A, he has hit .283/.343/.457.