Long Covid continues to evade a clear diagnostic test , researchers reported in a study published Monday in the Annals of Internal Medicine . The findings are part of the National Institute of Health’s RECOVER Initiative, a billion-dollar-plus effort launched in 2021 to research causes and treatments for the estimated 17 million Americans with long Covid. Monday’s study used data from more than 10,000 patients at 83 clinical sites around the country.

The researchers looked at a number of lab results from the patients, including routine blood counts; kidney and liver tests results; and markers of inflammation in the body. They found no differences between those with long Covid and those without the condition. Dr.

Kristine Erlandson, the lead author of the study and an infectious disease physician at the University of Colorado Anschutz Medical Campus, said she was disappointed they weren’t able to find a test that could clue doctors into long Covid. “I think it is consistent with what we’ve learned more recently,” Erlandson said. “It’s really a symptom-driven condition and there isn’t a specific laboratory value that points us towards that definition or diagnosing someone with long Covid .

” In an accompanying editorial , doctors at Johns Hopkins University School of Medicine wrote, “Clinicians are left to continue doing what we have done in the past: order tests to rule out alternative explanations rather than to diagnose long COVID.” Patients in the stu.