A young woman experienced spontaneous vomiting attacks during which she would sometimes retch more than 30 times a day and heave up to 1.6 gallons (6 liters) over the full course of an episode. It turns out, the symptoms likely stem from an underlying autoimmune disorder.
According to a report of the case, published Nov. 10 in the journal Frontiers in Endocrinology, the 27-year-old woman also has type 1 diabetes, an autoimmune disease in which the immune system attacks cells in the pancreas that produce the hormone insulin. Insulin helps shepherd sugar out of the bloodstream and into cells, but the disease reduces the body's supply of the hormone, which causes blood sugar, or glucose, levels to rise.
About 1 in 5 people with type 1 diabetes have an additional autoimmune disorder of some kind, according to a 2020 report in the journal Diabetes Care. In the woman's case, such an autoimmune disorder seems to drive her vomiting episodes, although her doctors are still working out how.
The doctors first examined the patient in 2016, when she began experiencing vomiting episodes about once a month. Before each, the patient felt an "impending sense of doom and came to our hospital for help in a state of panic," the authors wrote. The patient would then develop nausea, excruciating abdominal pain and vomiting. "The episodes were so severe that the patient had vomiting episodes more than 30 times a day and the vomiting volume could be as large as 6 liters [1.6 gallons]."
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Based on the pattern of the patient's episodes, the team diagnosed her with "cyclic vomiting syndrome" (CVS), a disorder characterized by sudden vomiting attacks interspersed with long periods without symptoms. The exact cause of CVS is unknown, but researchers think it might arise from errant nerve signals between the brain and digestive tract; dysfunctional hormonal responses to stress; or certain genetic mutations, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
After hospital admission, the patient's symptoms usually subsided over several days, but her blood sugar would then plummet and stay low for days, despite her insulin treatment being tightly controlled.
To unpack this complex case, the medical team conducted a whole-body exam, "but nothing significant was found," case report author Dr. Wei Liang, a physician in the endocrinology department at University of Hong Kong-Shenzhen Hospital, told Live Science in an email. However, an analysis of the patient's blood revealed "extremely high" levels of GAD autoantibodies, which are immune molecules that inadvertently attack the body's own tissues and are found in patients with type 1 diabetes, she said.
The patient's blood also contained antibodies that latch onto insulin, which can sometimes develop in people who need insulin injections. Oddly, the team found that the antibodies seemed to make the insulin hang around for longer than is typical for people who take insulin.
"We observed an unusual phenomenon of 'insulin recycling' in this patient," where the hormone was reentering the bloodstream rather than being efficiently broken down by cells, case report author Aimin Xu, a professor in the University of Hong Kong's State Key Laboratory of Pharmaceutical Biotechnology, told Live Science in an email.
There are several theories as to how insulin antibodies might cause this to happen, but the phenomenon isn't well understood. However, the antibodies did explain why the patient's blood sugar was dropping, so her doctors tried depleting the antibodies with different drugs. They found that rituximab, which tags antibody-producing immune cells for destruction, reduced the number of antibodies and corrected the low blood sugar.
Unexpectedly, "vomiting symptoms were remarkably reduced in our patient in the eight-month follow-up after one course of rituximab treatment," Liang told Live Science. The team suspects that the autoantibodies in the patient's blood were somehow driving her CVS, so when those antibodies disappeared, 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," she said.
To test this hypothesis, the team plans to study the patient's case and autoantibodies further, and eventually, they may consider conducting clinical trials with rituximab as a treatment for CVS, Xu said.
