A woman in Pittsburgh has become the first documented case in a living person of an unusual medical condition where alcohol naturally brews in the bladder from the fermentation of yeast.

The condition, which researchers propose to call either 'bladder fermentation syndrome' or 'urinary auto-brewery syndrome', is similar to another incredibly rare condition, auto-brewery syndrome, where simply ingesting carbohydrates can be enough to make you inebriated, even without consuming any alcohol via regular means.

In the new case, doctors became aware of what seems to be a related syndrome, after attending upon a 61-year-old patient who presented with liver damage and poorly controlled diabetes.

The woman visited University of Pittsburgh Medical Centre Presbyterian Hospital for placement on a liver transplant waitlist, with doctors having previously suspected her problems stemmed from alcohol addiction, due to repeated urine tests for alcohol showing consistently positive.

"Initially, our encounters were similar, leading our clinicians to believe that she was hiding an alcohol use disorder," her doctors explain in a new case report.

"However, we noted that plasma test results for ethanol and urine test results for ethyl glucuronide and ethyl sulfate, which are the metabolites of ethanol, were negative, whereas urine test results for ethanol were positive."

Furthermore, in addition to consistently denying having consumed alcohol, the patient did not appear to show signs of intoxication during visits to the clinic, even though her urine showed high levels of ethanol content.

Another mystery was the presence of large amounts of glucose in her urine – a condition called hyperglycosuria – with abundant levels of budding yeast seen in urine samples.

"These findings led us to test whether yeast colonising in the bladder could ferment sugar to produce ethanol," the researchers write.

Running tests on her urine, the team confirmed remarkably high levels of ethanol production, suggesting her strange results were due to yeast fermenting sugar in the bladder.

The yeast in question was identified as Candida glabrata, a natural yeast found in the body and related to brewer's yeast, but not normally discovered in such abundance.

Unfortunately, efforts to eliminate the yeast with antifungal treatments failed, perhaps due to the patient's poorly controlled diabetes. In light of the woman's seemingly unique predicament, the doctors note that she was reconsidered for liver transplantation, although their report doesn't make clear what ultimately became of the patient.

While researching the woman's case, the doctors became aware of other reports involving similar production of ethanol in urine, but only in one postmortem case, and in experiments run in vitro.

That said, it's possible other patients have presented with this rare medical condition before, but the symptoms weren't recognised, due to the unusual and largely unknown nature of the pathology.

"The experience we describe here of two liver transplant teams at different institutions demonstrates how easy it is to overlook signals that urinary auto-brewery syndrome may be present," the doctors say.

"Clinicians must be diligent about paying close attention to medical record documentation and laboratory results and should always investigate in the event of incongruences."

The findings are reported in Annals of Internal Medicine.