Sen. Chuck Grassley, the oldest and longest-serving senator, has been released from the hospital after treatment for an infection, his office announced Thursday.

“Senator Chuck Grassley (R-Iowa) has been discharged from the hospital and expects to be back to work next week,” an unsigned statement from his office said.

The senior GOP Iowa senator’s office said Tuesday that Grassley, 90, was “receiving antibiotic infusions” at a Washington-area hospital “to treat an infection.”

“He is in good spirits and will return to work as soon as possible following doctors’ orders,” the unsigned statement released Tuesday said. Grassley’s been in office since 1981.

Grassley’s office did not immediately respond to a request for comment on his current condition or when next week he will return to work.

Anthony Adragna contributed to this report.