NEW YORK – A new study supported by the National Institutes of Health and published this week found that routine laboratory tests are not reliably able to detect long COVID.
The study, published Tuesday in Annals of Internal Medicine, included more than 10,000 adults from the NIH's Researching COVID to Enhance Recovery (RECOVER) cohort, most of whom had a prior SARS-CoV-2 infection and nearly 19 percent of whom were identified as having long COVID. The study's participants completed surveys and underwent a physical examination and 25 standard laboratory blood and urine tests, and were then followed for two years, taking surveys every three months and laboratory tests at certain periods.
The study was conducted to determine whether a COVID-19 infection led to changes in biomarkers, such as platelet counts or protein in the urine, NIH said in a statement.
The lab tests, according to the study, detected very few differences in biomarkers between patients with prior infection and those without prior infection. Prior infection was associated with modest increases in HbA1c, but those increases disappeared after the researchers excluded people with preexisting diabetes, the NIH said.
There were also slight increases in uACR, which is a measure of low kidney function, but those may have resulted from severity of the initial infection, the NIH noted.
The researchers also conducted a secondary analysis looking only at patients with previous infection to determine the differences between those who developed long COVID and those who didn't. The study found no meaningful differences in lab test results between those who developed long COVID and those who did not.
"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," David Goff, director for the Division of Cardiovascular Sciences at the NIH’s National Heart, Lung, and Blood Institute, said in a statement.
"Future work will use RECOVER's biobank of cohort samples, such as blood and spinal fluid, to develop more novel laboratory-based tests that help us better understand the pathophysiology of long COVID," Kristine Erlandson, professor of medicine for infectious disease at the University of Colorado Anschutz Medical Campus, Aurora, and one of the study's authors, said in a statement.