Postural orthostatic tachycardia syndrome can be diagnosed by a simple blood test
POTS is distinguished by the substantial increase in heart rate and at times the decrease in blood pressure when one stands up. Symptoms of POTS include unconsciousness, light-headedness, and heart palpitations. Apart from fainting, POTS patients also observe additional symptoms like fatigue, pain, gastrointestinal issues, bleeding issues, anxiety, and brain fog.
POTS is known to affect nearly 3 million Americans but has been very challenging to identify due to its wide array of symptoms which are also seemingly unrelated.
“The issue in the diagnosis of POTS is that as of now there is only a clinical diagnosis possible. And this diagnosis is based on the medical history of the patient, the absence of other illnesses, and whether there is an increase in heart rate when standing up. There does not exist any kind of blood test right now to corroborate this diagnosis. This process can be extremely frustrating for the patients” states Dr. Blair Grubb, Distinguished University Professor of Medicine and Pediatrics in the UToledo College of Medicine and Life Sciences and Director of electrophysiology services at The University of Toledo Medical Center.
Journal of the American Heart Association published the largest study of POTS patients to date on September 9, reporting that 89% of these patients showed elevated levels of autoantibodies against the adrenergic alpha 1 receptor. This study was conducted by Grubb and UToledo research collaborators.
For years, small-scale studies along with many people suspect a theory of POTS having an autoimmune connection, says Grubb, one of the world's leading experts in syncope and disorders of the autonomic nervous system. "We did a much larger cross-section of patients than what has ever been done earlier, and we found that nearly all of them tested positive for autoimmune antibodies. That's a notable finding." In this cross-section, there were 55 patients out of which 52 were women. The average age was 30 and none of the 55 participants of the study had any other recognized autoimmune disorder.
Researchers tested the patients' blood for autoantibodies against nine receptors. Only a handful of patients reported elevated levels against all nine. However, it was the prevalence of adrenergic A1 subtype receptor autoantibodies that make these findings intriguing to delve deeper.
Dr. William Gunning, a professor of pathology in the UToledo College of Medicine and Life Sciences, and the paper's lead author says that “it is great to identify a biomarker. With these results, we have the ability to diagnose POTS, or at least come near to one. Like other autoimmune diseases, doctors, with the help of blood samples, can detect an increase in the levels of autoantibodies present. According to our results, autoantibodies against this specific receptor should be present in approx. 90% of POTS-affected patients."
Gunning and Grubb say that more research is required into this. However, this study builds on the evidence supporting that POTS is an autoimmune disorder. It reflects that it is a possibility for physicians to have an easy way to test for it. Grubb says “this provides proof for this theory. There have been other studies that have used very expensive research tests. What we did is that we used the same kind of testing mechanism but which would be available and used in regular hospitals. This is because of our aim to do something that can be a test which can be applied to the general population, and is not just a pure research test."
Gunning and Grubb clarify that they are still investigating the pertinent methods by which POTS is established and that their research makes it possible for existing immune-modulating medications to be a feasible therapeutic method in some patients.
This study gained funding from the Dysautonomia Advocacy Foundation, the Life as a Zebra Foundation, and the Virginia Lounsbury Foundation.