New research shows it is possible to diagnose asthma from a patient’s saliva. The method, which uses mass spectrometry to look for metabolic markers, holds promise as a non-invasive way to test for a condition that affects millions of people, many of whom are children.

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Unlike other sampling methods that are more invasive, the new test just needs a sample of saliva that can be collected from passive drool from patients of all ages.

Asthma is a chronic condition where the affected person has repeated attacks of breathlessness and wheezing. The attacks vary in severity and frequency from person to person.

During an asthma attack, the linings of the bronchial tubes swells. This causes the airways to narrow, which in turn reduces the flow of air in and out of the lungs.

While its causes are not completely understood, we do know that inhaling certain substances – such as allergens, tobacco smoke and chemical irritants – can trigger an asthma attack.

There is currently no cure for asthma, but it can be managed and kept under control to enable patients to enjoy a good quality of life. Tests for asthma are used to diagnose and monitor the condition.

Current clinical methods for diagnosing asthma, such as measurement of airflow lung capacity, are inaccurate and do not reflect underlying changes associated with the condition. Other tests using blood, sputum, or urine can be distressing, particularly for children.

Now, in a study published in the journal Analytical Methods, researchers from Loughborough University and Nottingham City Hospital in the United Kingdom describe how their method offers a simple, painless, non-invasive way to test for asthma.

For the study, the researchers collected saliva from patients with asthma and healthy people.

Fast facts about asthma
  • Around 235 million people worldwide have asthma
  • It is the most common noncommunicable disease among children
  • It occurs in all countries – regardless of their level of development.

Learn more about asthma

They then analyzed the samples using liquid chromatography-mass spectrometry (LC-MS) to identify and quantify “metabolic biomarkers” unique to the asthma samples.

The team notes in the study report:

“Ten discriminant features were identified that distinguished between moderate asthma and healthy control samples with an overall recognition ability of 80 percent during training of the model and 97 percent for model cross-validation.”

The team says not only can such a method diagnose asthma, it can also determine disease severity and progression.

One of the study leaders, Colin Creaser, a chemistry professor at Loughborough, says they decided to investigate LC-MS metabolic profiling of saliva as a potential diagnostic for asthma after using it to identify physiological stress from exercise. He says they were “very excited” to discover it would work for asthma.

There is still a way to go before doctors can start using the test, though. Further, longitudinal studies need to validate it. If they succeed, then it is likely that the method will be used for early asthma diagnosis as well as ongoing monitoring of patients.

Unlike other sampling methods, such as expired breath analysis, saliva can be collected by passive drool from the very young to the very old without causing distress.”

Prof. Colin Creaser

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