Doctors were baffled when one of their patients showed up at hospital and just could not stop throwing up.
The young woman was sometimes wretching as many as 30 times a day.
On a particularly bad day, that would involve chucking up six litres of sick.
The 27-year-old would have these vomiting episodes about once a month, according to a case study published in the Frontiers In Endocrinology journal last month.
The patient would be left feeling an "impending sense of doom” before each churn up from her insides, knowing the first release of vomit was unlikely to be her last.
The woman, who has Type 1 diabetes, visited hospital in 2016 in a “state of panic” about what she was going through.
With her condition so bad, doctors set about looking into what was driving this flurry of vomiting.
The team diagnosed her with "cyclic vomiting syndrome" (CVS), a condition characterised by sudden vomiting attacks interspersed with long periods without symptoms.
The exact cause of CVS is unknown.
But, researchers think the syndrome might arise from errant nerve signals between the brain to the digestive system.
It might also be a dysfunctional hormonal response to stress or based on certain genetic mutations, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
Experts suspected the woman’s symptoms likely stemmed from an underlying autoimmune disorder.
After hospital admission, her vomiting would usually subside over several days.
But, worryingly for a diabetic on insulin, her blood sugar would plummet, and stay low for days on end.
Dr Wei Liang, a physician in the endocrinology department at University of Hong Kong-Shenzhen Hospital, told Live Science a whole-body examination found “nothing significant”.
Yet closer inspection of the patient’s blood revealed “extremely high" levels of GAD autoantibodies — immune molecules that inadvertently attack the body's own tissues and are found in patients with Type 1 diabetes.
The presence of the antibodies helped explain why the patient's blood sugar was dropping low, so doctors cut them down using a drug called rituximab.
They did not actually think that would address the cycles of extreme vomiting, but the patient, during her follow-up appointment, was found to be faring much better.
“Vomiting symptoms were remarkably reduced in our patient in the eight-month follow-up after one course of rituximab treatment," Dr Liang said.
The Hong Kong medical team suspected that the autoantibodies in the patient's blood were somehow driving her CVS.
It meant that, when the antibodies were reduced, so too did the patient's vomiting episodes.
"In our opinion, cyclic vomiting syndrome is not likely linked to diabetes or insulin use," because the syndrome isn't more common in diabetic people than it is in the general public, Liang said.
"Therefore, we think CVS may be a separate autoimmune disorder.”
They plan to test their theory by studying the patient’s case and autoantibodies further, Live Science reported.
