The alleged victim of the assault had multiple sclerosis, Newcastle Local Court heard.

Wayne Ernest Wilton, 43, of Carrington, appeared on charges of assault, resisting police and shoplifting.

He pleaded guilty to the theft and not guilty to the other two charges.

A police facts sheet tendered to the court during a bail application said Wilton was at the Hunter Street Medical Centre, Newcastle West, about 1.30pm on Tuesday.

He was allegedly seated in the waiting room when a doctor called his name.

Wilton allegedly said to the doctor: "About time, you arsehole". The doctor replied: "I beg your pardon".

Wilton repeated himself and, feeling uncomfortable, the doctor turned to his secretary to arrange for another doctor to see him.

Wilton allegedly became angry and aggressive. He yelled abuse and threatened to "get" the doctor, police allege.

Wilton then approached the doctor with a clenched fist. The doctor became unsteady on his feet and turned to the reception desk for support.

Wilton then allegedly punched him to the kidney area. Wilton was restrained by two other patients, but allegedly continued to yell threats. He left after police were called.

Wilton was arrested a short time later with a bottle of whisky he had earlier stolen from a bottle shop. He allegedly struggled and tried to break free from police.

Solicitor Lachlan Cumming, for Wilton, said his client indicated he had bipolar disorder but was not medicated.

Magistrate Sharon Holdsworth refused bail, citing Wilton's history of violence and likelihood of him reoffending.

The case was adjourned to January 27.