Lynne Spalding, 57, was admitted to San Francisco General Hospital for treatment on September 19 and underwent treatment for infection.
Two days later, on September 21, Lynne Spalding disappeared.
San Francisco authorities and Spalding's family are seeking information on her whereabouts and appealing to the public for help in locating her.
"Lynne is an upbeat, lively person and her family's at a complete loss over her disappearance," family spokesperson David Perry said, in an interview with People.
Spalding, who had recently lost a great deal of weight, was being treated for an infection. Her condition was improving and listed as "fair" though family noted she seemed "very confused" when they last saw her.