An ambulance was called to Brisbane's Queen Elizabeth II Courts of Law on Monday after Clayton David Backman suffered an injury in his holding area.

Officials confirmed there was a "medical incident" at the courthouse and that paramedics attended to Backman but he was not required to be taken to hospital.

Backman, 31, was set to be sentenced in the Supreme Court on Monday on a total of 21 offences including manslaughter.

Backman was arrested when he handed himself in to police with a loaded gun in his pants after a 32-year-old father was fatally shot in Tingalpa, in Brisbane's east, in 2016.

Backman went to Brisbane City Watchhouse late at night in November 2016, telling officers over the intercom he'd been involved in a fatal shooting earlier that day.

He also told them he had a loaded, sawn-off shotgun down the front of his pants, prompting two officers to rush outside and draw their weapons on Backman.

However, Backman put his gun on the ground and was taken into custody without incident.

Backman remains in custody with sentencing rescheduled for Friday.

Australian Associated Press