Urine test 'can detect dangerous snoring'

It is estimated that up to 12% of children snore

A urine test that can differentiate between dangerous and safe snoring is possible, say researchers at the University of Chicago.

They looked at 90 children referred to a clinic to be evaluated for breathing problems in sleep, and 30 controls.

A number of proteins were increased in the urine of the children diagnosed with dangerous snoring.

The research is published in the American Journal of Respiratory and Critical Care Medicine.

The team say their findings need to be repeated but may lead to a simple test.

Sleep tests

The children all had standard overnight tests and some were classified as having obstructive sleep apnoea (OSA).

OSA is a big problem in children with large tonsils or who are obese Dr Ian Balfour-Lynn, Royal Brompton Hospital

OSA can lead to mental, behavioural, cardiovascular and metabolic problems in children. It is estimated that up to 3% of all children up to the age of nine may suffer from it.

The researchers collected the children's first sample of urine on the morning after the sleep study.

They used a process with fluorescent dyes to separate and characterise the proteins in the urine and found three proteins at higher concentrations in the urine of children with OSA: urocortin 3, orosomucoid and uromodulin.

Another protein, kallikrein 1, was at lower levels in the urine.

The scientists say further research is needed to work out which proteins work best for a test and the right time to get the urine sample.

They think that it may be possible to develop a simple colour-based test like a pregnancy kit that can be done by doctors or parents.

Diagnostic screening

"It was rather unexpected that the urine would provide us with the ability to identify OSA" said Dr David Gozal, who led the research.

"If we can develop this further we might be able to screen children for OSA for a fraction of the cost of keeping them in a sleep clinic overnight, and it would overcome the huge waiting lists for such screening."

Dr Ian Balfour-Lynn, a respiratory consultant at the Royal Brompton Hospital, which carries out many sleep studies on children, said: "OSA is a big problem in children with large tonsils or who are obese.

"Some overweight children with this problem have to use ventilators to sleep at night.

"This is an interesting finding - the implication is that the children's renal and kidney function is being affected by their OSA.

"But the research is too far from being something practical doctors and patients would be able to use."

Dr Paul Gringras, consultant in Paediatric Neurodisability and Sleep Medicine at the Evelina Children's Hospital, agreed that OSA was an important condition because of its harmful impact on physical health as well as learning and behaviour.

"The specialist centres that can accurately identify true cases are few, and at full capacity" he said.

"It is appealing to look at certain proteins from a single urine sample that could make the diagnosis.

"This study is the first step towards this possibility, but more work is needed to check the test is reliable, when the best time of day is to perform the test, and, finally, to simplify the biochemical tests so that they are easier to carry out."

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