A study reveals that routine laboratory tests are not effective in diagnosing Long COVID, challenging current diagnostic approaches and emphasizing the need for symptom-focused treatment.
The Limitations of Standard Blood Tests in Long COVID Diagnosis
The largest study of its kind, published in the Annals of Internal Medicine, examined data from nearly 10,000 adults across 33 U.S. states, Washington D.C., and Puerto Rico. Researchers found no reliable biomarkers among 25 routine clinical laboratory values for identifying prior COVID-19 infection, Long COVID (also known as Post-Acute Sequelae of SARS-CoV-2 infection or PASC), or specific PASC symptom clusters.
Dr. Kristine Erlandson, the study’s lead author and professor at the University of Colorado Anschutz Medical Campus, emphasized the importance of these findings: “Our study shows patients can have severe Long COVID with normal lab results. This suggests doctors should not focus on the results of blood panels to diagnose Long COVID but should focus more on symptoms and ways to help patients get relief by treating their symptoms.”
This research comes at a critical time, as approximately 7% of U.S. adults – nearly 18 million people – currently suffer from Long COVID, according to the Agency for Healthcare Research and Quality’s Medical Expenditure Panel Survey.
The Search for Reliable Biomarkers Continues
While the study found some statistically significant differences in certain lab values between those with and without prior SARS-CoV-2 infection, these differences were too small to serve as reliable diagnostic markers. Participants with prior infection showed modest increases in HbA1c (a marker of long-term blood sugar levels) and urinary albumin-to-creatinine ratio, along with small decreases in platelet counts.
Dr. David Goff, director of the Division of Cardiovascular Sciences at the NIH’s National Heart, Lung, and Blood Institute, highlighted the ongoing challenge: “Our challenge is to discover biomarkers that can help us quickly and accurately diagnose long COVID to ensure people struggling with this disease receive the most appropriate care as soon as possible.”
The study’s findings suggest that Long COVID may involve multiple physiological pathways beyond simple laboratory markers, such as those for inflammation or anemia. This complexity underscores the need for a more comprehensive approach to diagnosis and treatment.
Dr. Grace McComsey, senior author of the paper and professor at Case Western Reserve University, noted the implications for clinical practice: “Until a reliable biomarker is found, the best diagnostic modality for PASC remains the old-fashioned history taking and clinical assessment.”
Why it matters: This research has significant implications for both patients and healthcare providers. It highlights the importance of listening to patients’ reported symptoms and not dismissing concerns based solely on normal lab results. The study also emphasizes the need for continued research to develop more accurate diagnostic tools for Long COVID.
As the medical community grapples with the long-term effects of the COVID-19 pandemic, this study provides valuable insights into the limitations of current diagnostic methods. It underscores the importance of a patient-centered approach to Long COVID care, focusing on symptom management and relief while research into more definitive diagnostic markers continues.
Future research directions may include exploring advanced imaging techniques, genetic markers, or more specialized blood tests to identify reliable biomarkers for Long COVID. Additionally, developing standardized symptom assessment tools and investigating potential treatments based on symptom clusters could improve care for those affected by this complex condition.
