SAN FRANCISCO - The family of a missing teenager who recently suffered a traumatic brain injury said today that doctors have warned he could die if he is not found soon.

The family of Sean Sidi, 19, who has been missing since May 21st, is hoping the opinion issued this week by Dr. Geoffrey Manley, the chief of neurosurgery at San Francisco General Hospital, will help change Sidi's status with police to "medically disabled."

Police have said Sidi is considered at risk due to his medical condition. But changing his status to medically disabled would raise the priority level of the search with law enforcement and bring additional resources into play, according to family friend Kathleen Fazekas.

On the day of his disappearance Sidi went to visit a former high school teacher at 150 Oak St. in San Francisco around 11:40 a.m., according to his mother, Lynn Ching.

His last cellphone call to his father, Claude Sidi, was made around 1:30 p.m. and has been traced back to Golden Gate Park, Ching said. Search efforts have been focused at the park.

Sidi is described as being a slim male of mixed Caucasian and Asian descent, with dark brown hair and eyes and braces on his teeth. He is 5 feet 5 inches tall and weighs 120 pounds.

He was last seen wearing a black and gray North Face hooded rain jacket, jeans and black canvas shoes. He recently came out of an arm cast and was wearing a black splint on his left wrist and arm.

Anyone who thinks they may have information on his whereabouts should call San Francisco police Sgt. Ann MacKenzie at (415) 734-3268 or go to www.seansidi.com.

Family and friends are planning to hold an information vigil Sunday at 2 p.m. at Stanyan and Page streets in San Francisco.