Blood Thinners Don’t Make Your Blood Thinner

When I was a teenager, I was tentatively diagnosed with a genetic disorder called Marfan syndrome. The short explanation: My connective tissue is stretchier than normal, making me tall and somewhat gangly. It also has the potential to cause heart problems. But I’m a marginal case. So years of having a modest income and poor health insurance led me to avoid what should have been annual visits to a cardiologist to make sure my heart and aorta were running smoothly.

When I enrolled in the Johns Hopkins University science writing program I got my first decent health insurance in years. So I jumped on the opportunity to get re-evaluated at the age of 31, a good 15 years after the original diagnosis. Our knowledge of Marfan, as with most things, has grown in the last decade, and more than anything else I wanted to know if I actually needed to worry about my ticker so much that I needed yearly heart sonograms. So I went to the hospital and met with a cardiologist there.

To my relief, it turns out I don’t need yearly sonograms after all. But this story isn’t about that.

As we discussed my history, the cardiologist asked me what I was going to school for. I told him about the science writing program, and doing the tricky work of trying to simplify science for a general audience while not sacrificing our accuracy. His eyes widened, he tilted his head, and he leaned back in his chair a little. Something had just leaped into the doctor’s mind. I realized I was about to hear his opinion on what I do.

These platelets don't care how thin your blood is

He told me he wasn’t fond of the simplified term “blood thinners.” It’s often used to describe drugs that chemically control the microscopic bits and pieces — proteins, other molecules, and cell fragments called platelets — in our bloodstreams responsible for clotting. The doctor told me patients regularly assumed that blood thinners made their blood less gooey and more watery. He called it one of the more frustrating simplifications out there. “We have people around here on blood thinners who think they’ve got thin blood!” he said.

His statement got me thinking. My first impulse was to try to come up with ways the term could be defensible. Maybe if the drug reduced the number of clot-causing proteins, you could say the content of those proteins has become thinner? But I really felt like I was grasping.

The man had a point. Blood thinners just plain don’t make your blood thinner. It’s a convenient metaphor, attaching an every-day idea to a more complex biochemical concept, but it isn’t clear that it is a metaphor, which makes it easy to confuse the chemical changes going on in your bloodstream with a change in the blood’s consistency.

This is an old misconception, too, rooted in a very traditional way of thinking on blood thinness and thickness. If you’re interested in reading about what scientists know happens in blood compared to what the general public often thinks, check out this charming study on folk hematology, in which physicians and patients are interviewed on their familiarity with concepts like “thick blood” and “high blood.” This quote sums up the author’s take on “blood thinners”:

These drugs [“blood thinners”] are given to patients to prevent abnormal blood clotting. These drugs do not, as folk theory has it, “thin” the blood to a less viscous and more “watery” consistency. To avoid a befuddling biomedical explanation and accommodate a patient’s need for explanation, some physicians have opted for the term “blood thinner”, a term perhaps originally borrowed from their patients.

I had a sense of the issues with simplification before I joined the program — it is, after all, one of science writing’s central issues. I’m now seeing first hand how this kind of hazard pops up all the time, and we may not even be aware of it. Simplifications can be wonderful and elegant, or they can completely mislead. A metaphor can be brilliantly effective, but it must be clear that it’s a metaphor.

In the case of blood thinners, it’s probably naive to think the term will disappear from our language any time soon. Just type “blood thinner” into Google News, and hundreds of articles from the past month will pop up. The term is deeply embedded in our primal conceptualization of blood and drugs. Though I wonder what term would even make a good alternative. Clot stoppers?


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