Study finds that common lab tests aren't reliable for diagnosing long Covid

New Delhi, Aug 13: A new study reveals that most routine laboratory tests fail to reliably diagnose Long Covid, also known as Post-Acute Sequelae of SARS-CoV-2 infection (PASC). Published in the journal Annals of Internal Medicine, the research found no dependable biomarker among 25 routine clinical lab values for prior infection, PASC, or specific PASC symptom clusters, indicating that these routine tests are not clinically useful for diagnosing PASC.

“Our study demonstrates that patients may have severe Long Covid with normal lab results,” said Kristine Erlandson, Professor in the Division of Infectious Diseases at the University of Colorado Anschutz Medical Campus, US. “This suggests that doctors should focus on patients' symptoms and finding ways to alleviate them rather than relying on blood tests to diagnose Long Covid,” Erlandson said.

David Goff, director of the Division of Cardiovascular Sciences at the National Institutes of Health (NIH)’s National Heart, Lung, and Blood Institute, emphasised the urgency of identifying reliable biomarkers. “Our challenge is to find biomarkers that will allow us to quickly and accurately diagnose Long Covid, ensuring that people suffering from this disease receive the best possible care as soon as possible," he stated.

"Long Covid symptoms can prevent someone from returning to work or school and may even make everyday tasks a burden, so the ability to diagnose quickly is critical.” The team noted that till the time a reliable biomarker is found, history-taking and clinical assessment remain the best diagnostic modality for PASC.

The study underscores the complexity of Long Covid, suggesting it involves multiple physiological pathways beyond what can be detected through routine lab tests. The researchers also stressed the importance of continuing routine tests to rule out other conditions during Covid.