Like the Drexels, parents will do anything before giving up hope and calling off a search, wondering if the child is out there somewhere in need.
"Are they choosing to come home or unable to come?" Rando asked. "Are they lost or physically injured? They may be imprisoned or mistreated."
"You do whatever you can," she said. "Maybe one more flier, one more congressman to reach and one more reporter to give the story to can make a difference."
For the DuBois family of Escondido, Calif., whose daughter Amber has been missing since last February, the wait for answers that have never come has been devastating.
The 14-year-old was last seen 200 yards from the gate of Escondido High School. She had sent four text messages to her grandmother at 6:45 a.m. and was last seen by family friends around 7:15 a.m.
There have been few leads in her case. At the time of her disappearance, she was carrying a $200 check for a school program, and Valentine's Day gifts for her friends.
Her cell phone was turned on for a few minutes on the day following her disappearance but hasn't been used since.
"I'm hanging in there, but it's still hard to function every day," said her mother, Carrie McGonigle, who has a younger daughter from a new marriage. "It's hard to be a good parent to my 6-year-old. It's tearing up the family."
"She feels like we don't love her and that our focus is on finding Amber," said McGonigle. "She gets angry and her teachers say she has changed 360 degrees from nice to angry."
McGonigle is on antidepressants for stress and has not been able to work at her customer service job at a printing company in four months.
"It's utterly devastating and tears us apart," said Amber's father, who is an electronic engineer. "I haven't worked a day since she went missing."
"All we have is our hope, and when you lose that, all is gone," said Maurice "Moe" DuBois.
If you have any information regarding the disappearance of Amber Leeane DuBois, please contact Amber's Search Center at (760) 743-7343.
For Kelly Jolkowski, who has waited for her son Jason's return for eight years, activism has helped her cope.
Jason disappeared at the age of 19 on June 13, 2001 -- an anniversary that will hit the family hard on Saturday. He left home to meet a co-worker who was supposed to drive him to work.
He was last seen by his younger brother Michael taking the trash out in their Omaha, Neb., driveway.
"He had no enemies. He was a nice kid. No one hated him, and there is no evidence of mental health issues or family problems," she told ABCNews.com. "He doesn't look like a runaway and there is no evidence someone took him."
She said she replays that day forever in her mind.
"Parents always wonder if they could have done something to prevent this," said Jolkowski. "They always play back the last day or the last week."
Parents of a missing teen might worry that things may have been different had they not yelled at the child about picking up his clothes.
The Jolkoski's marriage has remained intact, despite the pressures, and a close network of friends and extended family have softened the pain.