The post looked simple enough: Kim Kardashian, hair pulled back in a ponytail, posed in front of an MRI wearing scrubs branded with the logo of medical imaging company Prenuvo.

“I recently did this @prenuvo scan and had to tell you all about this life saving machine,” she wrote. The MRI could pick up on traces of cancer or other diseases, she said.

But the post was too simple, University of Sydney public health researcher Brooke Nickel thought when she saw it in August 2023. What about the possible harms? The test might find an extremely early stage cancer that would lead to invasive treatment, even though it may never have progressed to something more serious. Kardashian’s post made it seem as if there were only upsides.

That post, and others like it, prompted Nickel to look into how celebrities and influencers promote increasingly popular medical tests such as full-body MRI scans. They also examined posts for products that claim to detect cancer in blood or analyze a hormone linked to fertility, testosterone levels and the gut microbiome.

The results of that study, which scrutinized nearly 1,000 TikTok and Instagram posts from accounts with hundreds of millions of combined followers, were published last week. The paper found that an overwhelming majority of these posts were misleading, painting an overly rosy picture of these tests and rarely including scientific evidence. Only 15% mentioned potential harms. More than two-thirds came from accounts with financial ties to the products, like influencers offering discounts and receiving sales commissions.

“If this is how patients are getting all their information, it’s really unfortunate, because it’s completely acting like medical tests are a new cool pair of sneakers,” said Dr. Rebecca Smith-Bindman, director of the Radiology Outcomes Research Laboratory at the University of California, San Francisco, who was not involved in the study.

One of Nickel’s concerns was that test results could lead to overdiagnosis, or identifying problems that would most likely never have warranted treatment. Overdiagnosis can lead to costly and invasive procedures that may be unnecessary.

“That’s a tough concept for people to get, that more information could be harmful,” said Dr. Michael Pignone, vice chair for quality and innovation at the Duke University School of Medicine. “To do justice to why more information is not always better oftentimes requires more than 140 characters.”

Some of the tests the researchers looked at advertised benefits that were not supported by evidence, like the test for anti-Müllerian hormone. The new study found posts heavily marketing the test to young women as a way to assess their fertility potential, Nickel said. Women might act on their results and choose to freeze their eggs or undergo expensive treatments, even though AMH cannot reliably predict general fertility.

It’s possible that a test like a full-body MRI could save lives, Smith-Bindman said. But the vast majority of MRIs conducted in patients who do not have any symptoms will likely lead to “just finding things that there’s no benefit to finding,” she said.

Christine Alabastro, a spokesperson for Prenuvo, wrote in a statement to The New York Times that “while conversations around overdiagnosis are important, our approach is designed to maximize meaningful insights while minimizing unnecessary interventions.” She added that 1 in 20 people who undergo a Prenuvo scan “discover a potentially lifesaving finding.”

Prenuvo does not pay anyone to promote its products, but it does offer free or discounted scans to high-profile figures.

Around half of the posts that researchers reviewed encouraged viewers to get these tests themselves, despite the fact that there is not strong evidence that they improve outcomes for healthy people, the authors wrote. Some also encouraged consumers to buy specific treatments, such as testosterone replacement therapy.

“They’re selling it as a way of taking control of your health and empowerment,” Nickel said.If you see a post discussing medical tests on social media, ask yourself whether it is trying to convince you of something, rather than just providing information, suggested Tara Kirk Sell, a senior scholar who studies misinformation at the Johns Hopkins Center for Health Security. You should also consider whether a post acknowledges what scientists don’t yet know about a particular test or topic.

Keep in mind that personal stories “trigger an emotional response” that draws you in, Sell said. “It may be for good reasons. It may be for bad reasons. But it’s a technique.”