Hornsey and Wood Green MP Lynne Featherstone said there was no evidence to support proposals to close the A&E department at Whittington Hospital in north London.
In a Westminster Hall debate on 17 March 2010 Ms Featherstone said "sweeping" changes planned by NHS London could see the hospital lose its emergency department.
The Lib Dem MP said the move would mean local residents having to travel much further for emergency treatment.
She added that the hospital was in a socially deprived area where many people were not registered with a GP, and were therefore reliant on Whittington's A&E should they become ill.
"I do not know a single person locally who doesn't think this is sheer madness," she said.
Health Minister Mike O'Brien said reforms were being driven by local clinicians.
The minister said he had seen no evidence to suggest that Whittington's emergency department should close.
"I'm very sceptical about it," he said.