Hope for the 1 in 3 Americans with liver disease: New stool test could spot the condition years before symptoms arise without the need for invasive tests
- Left undetected, early-stage liver disease can turn into serious damage, but it is hard to spot early
- There are few symptoms and definitive diagnosis historically requires surgery
- A new UC San Diego study suggests a way to spot signs with a stool test
A stool test could detect liver disease before symptoms arise without the need for invasive tests, a new study found.
The new method looks at bacteria in stool, which can tell doctors if non-alcoholic fatty liver disease (NAFLD) is at an early or advanced stage.
Early-stage NAFLD, a build-up of fat in the liver, affects one in three Americans and Britons, with the case-load rising as waistlines expand.
If left undetected, it can develop into serious liver damage, including cirrhosis, but it is incredibly difficult to catch early because there are few symptoms and it requires surgery.
Now, a study by researchers at the University of California, San Diego, has identified unique patterns of bacterial species in the stool of people with the condition.
Left undetected, early-stage liver disease can turn into serious damage, but it is hard to spot early. There are few symptoms and it requires surgery. A UC San Diego study suggests a way
‘If we are better able to diagnose NAFLD-related cirrhosis, we will be better at enrolling the right types of patients in clinical trials, and ultimately will be better equipped to prevent and treat it,’ professor of medicine Dr Rohit Loomba said.
‘This latest advance toward a noninvasive stool test for NAFLD-cirrhosis may also help pave the way for other microbiome-based diagnostics and therapeutics, and better enable us to provide personalised, or precision, medicine for a number of conditions.’
The precise cause of NAFLD is unclear, but both diet and genetics play substantial roles.
Up to half of people with obesity are believed to have NAFLD, and people with a first-degree relative with NAFLD are at increased risk for the disease.
In a previous study of patients with biopsy-proven NAFLD, Dr Loomba and colleagues found a gut microbiome pattern that distinguished mild/moderate NAFLD from advanced disease.
This allowed them to predict which patients had advanced disease with high accuracy.
In the new study, Dr Loomba’s team wanted to know if a similar stool-based ‘read-out’ of what is living in a person with NAFLD’s gut might provide insight into their cirrhosis status.
The microbial makeup of stool samples from 98 people known to have some form of NAFLD and 105 of their first-degree relatives, including some twins were analysed.
This was done by sequencing the 16S rRNA gene, a genetic marker specific for bacteria and their relatives, archea.
The 16S rRNA sequences serve as ‘barcodes’ to identify different types of bacteria and the relative amounts of each, even in a mixed sample like stool.
Researchers first noticed that people who share a home also tended to share similar microbial patterns in their gut microbiomes, further validating several previous studies.
In addition, they observed that people with extreme forms of NAFLD had less diverse and less stable gut microbiomes.
The team then identified 27 unique bacterial features unique to the gut microbiomes, and thus stool, of people with NAFLD-cirrhosis.
They were able to use this noninvasive stool test to pick out the people with known NAFLD-cirrhosis with 92 per cent accuracy.
But more importantly, the test allowed them to differentiate the first-degree relative with previously undiagnosed NAFLD-cirrhosis with 87 per cent accuracy.
The results were confirmed by magnetic resonance imaging.
The stool-based microbiome diagnostic could be available within five years and would cost around £300.
Dr Loomba also pointed out that while a distinct set of microbial species may be associated with advanced NAFLD-cirrhosis, the study does not suggest that the presence or absence of these microbes causes NAFLD-cirrhosis or vice versa.
The study was published in the journal Nature Communications.