The Allegheny County medical examiner says Estelle Cepek, of Blawnox, died Sunday night at UPMC Presbyterian hospital.
She had been there since she was hit by what police believe was a dark-colored pickup truck in the parking lot of a McDonald's restaurant in the city's East Liberty section about 7:15 a.m. Wednesday.
Police say Cepek was originally listed in fair condition and expected to survive before doctors discovered broken bones and other internal injuries.
The victim volunteered by answering calls at a behavioral health center near the restaurant where she walked to get her morning coffee each day.
Police have yet to charge or identify the driver.