The government has been urged to improve support for the "heartbroken" families of people who go missing.
The UK's first parliamentary inquiry into the issue heard from campaigners who say there is a "complete gap" in help for those affected.
Kate McCann, whose daughter Madeleine vanished abroad in 2007, told MPs it should not be down to "grieving parents" to search for their child.
The prime minister's official spokesman said help for families was a priority.
Mrs McCann, from Rothley, Leicestershire, is one of three mothers giving evidence over four sessions.
She said grief was compounded by a "lack of communication and information", and called for a single point of contact between families and the police.
"To be left in the dark when your child is missing and at risk is unbearable," she told the inquiry.
"Many people have been worn down by this process because it's absolutely relentless and exhausting."
Madeleine was three went she went missing during a family holiday in Portugal.
The other mothers who gave evidence were Sarah Godwin, whose son Quentin was 18 when he went missing in New Zealand while on his way to an after-school job in 1992, and Nicki Durbin, whose son Luke was 19 when he disappeared after a night out in Ipswich five years ago.
Mrs Godwin said her son could be anywhere, but has strong roots with England because she is from England and he was very close to her English parents, who have since died.
She told the BBC: "I think it's the connectivity that's really important for the families, or people who are struggling with a missing relative, not to have to search around and work out who to talk to."
Ms Durbin said: "There isn't an hour of a day that goes by without me thinking about Luke.
"If my house was burgled, I would have got support... when I reported Luke missing, there was nothing. And there still isn't anything."
She has been backed by the charity Missing People, which says that after 48 hours relatives should be given support similar to that given to the victims of serious crime.
This includes a dedicated police officer as well as emotional and practical advice.
Chief executive Martin Houghton-Brown told the inquiry that up to 20,000 families a year could benefit from his charity's support, but many did not know it was there.
Earlier, he told the BBC that all families of missing people were immediately "plunged into emotional distress".
"If the person going missing is also earning money for the family, they may be placed in financial or legal difficulties as well," he added.
MPs at the inquiry also heard from Home Office Minister James Brokenshire, who said he would continue to work closely with the voluntary sector to provide additional funding for Missing People.
Peter Lawrence, father of missing York chef Claudia Lawrence, will give evidence later in the week along with Rachel Elias, the sister of missing Manic Street Preachers guitarist Richey Edwards.
The inquiry will also consider calls to make it easier to register the death of a missing person whose body has not been found, in order to sort out their financial and legal affairs.
Courts can be asked to declare someone dead after seven years, although in England and Wales it is not statutory.
Ms Elias, whose brother Richey Edwards went missing in a high-profile case in 1995, says getting a missing person declared dead is too complicated.
She told BBC Radio 4's Today programme: "There were no advisory organisations out there to help us to know what to expect.
"Our solicitor was very good but it was in fact the first time that he had done it. It was difficult enough for us, and for families who have wider issues to deal with, such as dissolving a marriage or dealing with joint assets, it's an even more difficult process."
Prime Minister David Cameron's official spokesman said he was working hard to ensure the "best arrangements" were in place to support families.
And assistant chief constable Phil Thompson, from the Association of Chief Police Officers (Acpo), said: "This is crying out for a national strategy for missing people."
The inquiry will examine whether a new system is needed for the national database of unidentified bodies - currently totalling 1,000 - to match these details with information about missing people.
Organised by the All Party Parliamentary Group on Runaway and Missing Children and Adults, it will make recommendations to the coalition government.
From 1 July, the Child Exploitation and Online Protection agency will take over responsibility for missing children.