Hoping to gain insight into the best way to diagnose and monitor inflammatory bowel disease (IBD), researchers from several hospitals in Zurich, Switzerland, asked 16 healthy adults to drink 10 shots worth of their own blood and then collect their stools for analysis. The resultant study, titled “The Vampire Study: Significant elevation of fecal calprotectin in healthy volunteers after 300 ml blood ingestion mimicking upper gastrointestinal bleeding”, was recently published in the United European Gastroenterology Journal.
So… Let us explain.
The term IBD refers to a family of poorly understood autoimmune conditions characterized by chronic inflammation of the digestive tract that induces diarrhea, abdominal pain, fever, fatigue, and other unpleasant symptoms. Without knowing what causes IBD, gauging who has it and whether or not that person is experiencing a flare-up can be quite challenging, especially since the degree of inflammation within the intestine does not always correspond with the severity of symptoms.
Currently, the best testing method involves measuring the amount of a protein called calprotectin present in one’s poop. Fecal calprotectin (fC) serves as a good biomarker of active IBD because it is abundant in neutrophils, a type of immune cell that swarm the lining of the intestines during these periods of self-attack. Yet neutrophils are always present in human blood, and therefore people experiencing gastrointestinal (GI) bleeds would also show elevated levels of fC, which could “erroneously indicate active inflammation in IBD”, according to the authors. To make matters more confusing, those with IBD often experience upper GI bleeds, and as of now, the only way to clearly distinguish if a patient’s bleeding is IBD related or from another cause is to perform an endoscopy, but this procedure is expensive and invasive.
Thus, the team led by Dr Stephan Vavricka, head of the Gastroenterology and Hepatology division at the Triemli Hospital, set out to determine how much blood has to pass through the GI tract into the poop to result in fC levels at or above the threshold physicians consider indicative of IBD. And the only way to mimic GI bleeding without causing real harm is to ingest it.
Despite experiencing high rates of the common side effects of high blood intake – nausea, diarrhea, heartburn, and constipation – the authors reported that participants handled the unusual experience well.
Subsequent analysis of their poop revealed that elevated fC levels (> 50 µg/g) were rare at baseline, yet very common in the three days following consumption of 300 ml of blood, and somewhat common immediately following 100 ml consumption.
The good news is that fC levels above 250 to 300 µg/g – the established cut-off for relevant intestinal inflammation in patients with inflammatory bowel disease, per the authors – was only seen in one individual. Given that 100 and 300 ml are significant blood volumes, the authors conclude that it is unlikely that GI bleeding is confounding IBD fC tests, and that the high levels seen in IBD individuals are indeed from the migration of neutrophils.
The team does caution, however, that severe bleeding, such as from an ulcer or as in ulcerative colitis, could potentially muddle the test.
[H/T: Live Science]