NEW YORK – Though testing laboratories and test manufacturers have been making improvements to mitigate the effects of biotin interference in immunoassay testing, it remains a headache that both continue to have to grapple with.
"We're not completely out of the woods," Brooke Katzman, a codirector of the hospital clinical laboratory and point-of-care testing at the Mayo Clinic, said in an interview.
In November, the US Food and Drug Administration updated a safety communication about the potential of biotin interference with lab tests. This followed a 2017 warning the agency issued that ingesting high levels of biotin, also known as vitamin B7, can lead to incorrect lab test results.
Then in January, the American Association for Clinical Chemistry issued a guidance instructing clinicians, lab professionals, and patients how to prevent biotin from interfering with test results.
The guidance highlights the need for good communication between clinicians and labs to ensure doctors and patients understand what tests might be affected by patient biotin use and to keep labs informed about patients' biotin intake, the AACC said.
Together, the issuances of the two recent communications suggest that labs and diagnostic test makers may not be as proactive in dealing with the issue as is necessary. As Katzman said, diagnostic manufacturers are working to update some assays, and "there's a lot more awareness of the interference among laboratories now."
But while "communication between labs and physicians and between physicians and patients has really helped," diagnostic companies and laboratories still have a lot of work ahead of them to manage the issue, she noted.
Biotin – a nutritional supplement taken by some to improve the appearance of their hair and nails, among other things – and the issue it can cause for immunoassays, has been on the radar of laboratories for several years. In a 2017 study published in JAMA, investigators at the University of Minnesota, Boston Medical Center, Children's Mercy Hospitals, and Johns Hopkins Medical Institutions assessed the performance of specific biotinylated immunoassays after patients ingested 10 mg/d of biotin, a level often found in over-the-counter supplements for healthy adults.
The group evaluated the performance of 37 immunoassays for the analytes on four diagnostic systems. Of the total, 23 assays incorporated biotin and streptavidin and rest served as controls.
Among the two women and four men who took biotin for seven days, biotin ingestion-associated interference was found in nine of the 23 biotinylated assays compared with none of the 14 nonbiotinylated assays. Results from five of eight biotinylated competitive immunoassays tested falsely high and results from four out of 15 biotinylated sandwich immunoassays tested falsely low.
Sihe Wang, director of clinical laboratories at Akron Children’s Hospital in Ohio, said that in managing issues associated with biotin interference, "most laboratories are relying on the packing information from the test manufacturers and what is available in the literature. If somebody is taking a low dose of biotin, there's a 99.9 percent chance that you don't have interference. If somebody is taking a high dose of biotin, 100 milligrams per day, for example, certain tests are going to have interference."
In 2018, Katzman and fellow laboratorians at the Mayo Clinic investigated the prevalence of biotin consumption by surveying the outpatient population using a questionnaire and by quantifying biotin in plasma samples collected from patients presenting to the emergency department.
In a study published in Clinical Biochemistry, they noted that of 1,944 patients that returned completed questionnaires, 7.7 percent indicated biotin use. By measuring levels of biotin in emergency department's plasma samples, the group found that 7.4 percent had concentrations at or above the lowest known threshold (10 ng/mL) for biotin interference in Roche Diagnostics immunoassay tests.
The investigators concluded from the study that biotin is common and the range of biotin concentrations in emergency department patient samples "highlights the magnitude of the biotin interference problem and identifies a population at risk for potential harm."
The endocrinology group at Mayo Clinic currently addresses the issue of potential biotin interference by closely observing the results of patients' thyroid function tests. Among the challenges seen by Katzman and her colleagues is that patients' biotin intake is not always reflected in their clinical records.
Ensuring that patients are reporting not only their prescription drugs, but also the multivitamins and supplements they are taking has become part of ongoing activities to mitigate the effects of biotin on immunoassay results, she said.
Mayo Clinic also developed a troubleshooting protocol to investigate biotin interference in its immunoassay tests. "We've developed a procedure where we can remove biotin from the specimen and determine whether it caused or something else caused interference," Katzman said. "Anytime a result doesn't match [our clinicians'] expectations, they'll call us. And it's not always biotin causing the interference. We know that there are several other interferences at play."
Patrick Kyle, an author of the AACC guidelines and a director of clinical chemistry and toxicology at the University of Mississippi Medical Center, said that almost "every laboratory immunoassay has some component that could interfere with a test result, so this is not uncommon in laboratory testing and we deal with it every day."
However, diagnostic manufacturers are continuing to work on assays to mitigate the effects of biotin, Kyle said. "You can imagine that a test for heart disease or cancer testing could have significant ramifications if it provided a false negative or false positive result."
While it is recommended that labs use assays that are not affected by biotin, most are locked into three- to five-year contracts with their instrument vendors, he said.
However, most labs have developed methods to deal with results that are suspect. "If there is a questionable result of some concern to a clinician, a laboratory has the option to send out samples for testing on biotin-free platforms," Kyle said.
Further, companies are developing products that enable laboratorians to remove biotin from specimens. One, developed for research-use only, is from Charleston, South Carolina-based Veravas.
In February, Veravas announced it had raised $4 million from private investors through the issuance of convertible notes, and last week it announced that it had entered into an agreement with molecularly imprinted polymers (MIP) specialist MIP Diagnostics to develop, license, and supply a novel MIP for Veravas' sample preparation technology.
Carmen Wiley, the company's chief medical officer, said the firm has developed two products that are being used mainly by high complexity CLIA -certified academic laboratories to assist with the issue of biotin interference.
The firm has developed a rapid point-of-care assay, VeraTest, that tells the user whether the biotin concentration is less than 15 nanograms per milliliter in a sample. Laboratories looking to treat all tests with possible interference can opt for VeraPrep, a product that enables comparing results by testing the freshly drawn sample and one treated with the Veravas product.
Developers of diagnostic platforms are also taking steps to address the issue of biotin interference.
In the context of monitoring for biotin interference, Roche has a "post-market monitoring system" that enables it to track specific trends and determine whether they are "happening more often than in the past," said Dusanka Kasapic, senior medical affairs manager for centralized and point-of-care solutions at Roche. "This is something that we do routinely and if you look at the total number of cases that people report where test results have been affected by biotin, it is a pretty low number compared to the high number of tests that are done using our immunoassay platforms."
Kasapic and her colleagues published the results of a research study in 2017 in the journal Future Science that evaluated population pharmacokinetics of exogenous biotin and the relationship between biotin serum levels and in vitro immunoassay interference.
The Roche researchers noted at the time of the study that guidance on how to mitigate the risk of biotin interference in streptavidin-biotin-based assays varied from one diagnostic test manufacturer to another. "The spectrum of guidance provided in package inserts ranges from no mention or a vague generic warning of biotin interference, which is insufficient as it does not create awareness of potential issues, to the more comprehensive specification of a serum biotin concentration below which assay interference is minimal, for example, [less than or equal to a] 10 percent change," the researchers wrote.
They added that the findings for the study "provide clear guidance on washout periods required for assays with interference thresholds ranging from 10 to 100 ng/ml" following specific dose regimens.
Some of the manufacturers at the time didn't have a biotin warning in the message sheet that accompanies the test, which is something they have since changed, Kasapic said in an interview. "Interference is something that can always happen in a laboratory, and biotin interference is rare," she said. It is not necessary to update all assays to mitigate for biotin interference, but there are certain circumstances, such as when patients with multiple sclerosis are taking exceptionally high dosages of biotin, that need careful attention.
"For this specific patient group, Roche decided to update some assays, not because biotin interference is a higher risk for patients overall, but because it helps to manage testing for this specific group of patients," she said.