FDA issues an alert about the potential for erroneous results caused by high levels of biotin in patient samples
Interview by Steve Halasey
At the end of November 2017, FDA issued a safety alert for the public, healthcare providers, laboratory personnel, and lab test developers about the potential for biotin to interfere with certain lab tests and cause incorrect results that may go undetected.1
Many lab tests use biotin technology due to its ability to bond with specific proteins that can be measured to detect certain health conditions. For example, biotin is used in hormone tests and tests for markers of cardiac health, such as troponin. However, high levels of biotin in patient samples can cause falsely high or falsely low results, depending on the format of the test. Clinical decisions based on such incorrect laboratory test results may lead to patient harm due to inappropriate diagnosis and treatment.
Also known as vitamin B7, biotin is a water-soluble vitamin often found in dietary supplements, multivitamins, and prenatal vitamins. Some supplements—particularly those labeled for hair, skin, and nail benefits—may provide high doses of biotin, which may not be clear from the label. It’s important for consumers to let their doctors and lab personnel know if they are taking biotin supplements.
However, biotin doesn’t interfere with all test results. Tests that do not employ biotin technology are not affected by biotin interference, so patients whose samples are evaluated using such tests do not need to be concerned about the issue or stop taking supplements before their blood tests.
FDA is working with stakeholders to better understand biotin interference with laboratory tests, and to develop additional recommendations for safe testing among patients who have taken high levels of biotin when using laboratory tests that use biotin technology. To find out more about FDA’s recent alert and its effects on the clinical laboratory community, CLP recently spoke with Ramani Wonderling, PhD, associate director for scientific relations in diagnostics at Abbott, Abbott Park, Ill.
CLP: In diagnostic tests that employ a biotin technology, what role does biotin play?
Ramani Wonderling, PhD: More than 25 years ago, some developers of in vitro diagnostics (IVDs) created lab tests using the strong noncovalent interaction between biotin and streptavidin. The method employs streptavidin-coated microparticles to capture biotinylated antibody or antigen that has been attached to the target analyte, yielding a result based upon the amount captured. This method is referred to as the ‘free capture’ biotin-streptavidin assay method, and it is vulnerable to biotin interference. If a patient takes biotin supplements, the free biotin in the patient’s blood sample can interfere with this method and lead to incorrect lab results (see Figure 1).
By contrast to the ‘free capture’ method, if a lab test uses biotin as part of a ‘preformed complex,’ it’s less likely to have biotin interference. From a reading of package insert instructions, however, it’s not always easy to determine whether a particular test uses the free capture or preformed complex method. If lab personnel have questions about whether a testing method is affected by biotin interference, they should communicate with the IVD developer.
CLP: When it comes to dealing with the results of such biotin-based diagnostics, why is biotin interference problematic?
Wonderling: Biotin offers multifaceted health benefits. It’s readily available for people to purchase over the counter and ingest in doses varying from 5 mg to 10 mg. Doctors may also prescribe biotin for various health conditions, and people may take biotin as part of intravenous drips or as part of a multivitamin regimen. There have been no reported side effects associated with taking biotin supplements.
At higher doses, biotin supplements can affect some lab test results, and this interference is problematic for a few reasons. With such widespread availability and use, it’s not always possible for healthcare systems—including hospitals, laboratories, and doctors’ offices—to know which patients may be taking biotin. If those facilities use lab tests based on the free capture biotin-streptavidin method, they may produce incorrect test results. Those falsely lowered or falsely elevated test results may lead to misdiagnoses or unnecessary treatments for conditions as varied as breast cancer, fertility, heart disease, pregnancy, and thyroid conditions.
Among pregnant women, for example, tests that are affected by biotin interference may produce falsely low measurements of beta human chorionic gonadotropin. Such erroneous results could lead the physician to rule out early pregnancy, thereby raising the potential for a pregnant woman to be inadvertently exposed to x-rays or computed tomography scans that could harm the developing fetus.
In fact, FDA has reported seeing an increase in the number of reported adverse events, including one death, related to biotin interference with lab test results. Clinical laboratories can avoid these issues by selecting and using lab tests that are not vulnerable to biotin interference.
CLP: Does the problem of biotin interference only apply to tests that use blood samples? How do high levels of biotin skew test results?
Wonderling: To date, this interference problem is known to apply only to blood samples, as the free biotin in the subject’s blood interferes with the ability of streptavidin to capture the biotinylated target. In tests that use the free capture biotin-streptavidin method, the levels of biotin that people currently take can skew results. The interference can produce either a falsely lowered or a falsely elevated test result, depending on the assay format, which may lead to the misdiagnosis of patients.
CLP: How does the assay format determine whether test results will be falsely elevated or lowered by excess biotin?
Wonderling: IVD developers typically employ one of two assay formats. If the test is formatted as a sandwich assay, where the target analyte is sandwiched between two antibodies, excess biotin can result in test results that are falsely lowered (see Figure 2). On the other hand, if the test is formatted as a competitive assay, where the target analyte competes with the labeled analyte, the results may be falsely elevated (see Figure 3).
CLP: Why is it of concern if a cardiac troponin or sepsis test is affected by biotin interference?
Wonderling: Cardiac troponin is a protein whose presence in the blood can be a sign of injury to the heart muscle, so immediate troponin testing is indicated for patients who are suspected of having a heart attack. To help diagnose heart attacks, doctors use troponin lab tests to detect changes in troponin levels because troponin levels rise when heart cells are damaged. Although a small proportion of suspected heart attacks is diagnosed by means of electrocardiograms or clinical findings, in most cases clinicians rely on a troponin result to help guide patient management.
For a patient who may be having a heart attack, time is of the essence. Testing cannot be delayed while waiting for an elevated level of biotin to be cleared from the patient’s system. When a patient presents with chest pain, for example, it’s important to carry out an evaluation promptly to determine whether the patient needs immediate transfer to a coronary care unit or catheterization lab for further care. A falsely low troponin test result due to biotin interference could lead to grave consequences, including delays in follow-up testing, misdiagnosis, late initiation of treatment, or even death.
Similarly, in cases where a patient is suspected of having sepsis, testing to determine the blood level of procalcitonin may be useful for patient management and treatment. But if the test generates erroneous results, it could cause some confusion and possible delays. In the case of sepsis, every hour of delay in diagnosis increases patient mortality by 7.6%.2
CLP: How long does biotin stay in the body? After taking biotin, for instance, can patients get rid of the potential for interference by waiting for a few hours before having their blood drawn?
Wonderling: Current data suggest that the length of time required to clear biotin from patient samples may vary from a few days to a few weeks.3–5 Ordering physicians need to consider the amount of biotin taken by the patient, how long the patient has been taking biotin, and how vulnerable the ordered test may be to biotin interference.
Even on the same lab platforms, some tests are more vulnerable to biotin interference than others. In its November 2017 safety communication, FDA noted that “currently available data is insufficient to support recommendations for safe testing using affected tests in patients taking high levels of biotin, including about the length of time for biotin clearance from the blood.”
CLP: Are all lab tests and lab platforms affected by biotin interference?
Wonderling: The good news is that not all lab tests and lab platforms are vulnerable to biotin interference. Having access to such nonvulnerable tests is critical for evaluating patients in acute care situations, such as heart attack or sepsis. For example, lab tests currently available from Abbott are designed in such a way that biotin doesn’t affect the test results. Abbott has investigated the company’s four assays that use biotin, and has confirmed that there is no interference when biotin is introduced up to 1000 ng/mL.
CLP: What are the practical alternatives to biotin technology in current use by test developers?
Wonderling: There are practical alternatives to the biotin technology. One example of an alternative methodology is the magnetic separation technology used by the Abbott Architect platform. In this method, magnetic microparticles coated with antigen or antibody are used to capture the target analyte, and are then separated from the rest of the sample using a magnet (see Figure 4). The free capture streptavidin-biotin method is not used, so biotin in the patient sample doesn’t interfere with the test results.
CLP: Have any adverse events involving patients been reported as a result of biotin interfering with lab results?
Wonderling: According to the FDA safety communication, the agency has seen an increase in the number of reported adverse events related to biotin interference with lab test results, including one death.
CLP: What is FDA advising patients and healthcare providers to do?
Wonderling: FDA encourages consumers to know whether the supplements they’re taking contain biotin. If they do, consumers should let their doctors know that they’re taking biotin. If consumers are concerned about their lab test results, they should talk to their doctors about the possibility of biotin interference.
FDA also advises healthcare providers to be aware that many lab tests employing biotin technology are potentially affected, and that incorrect test results can be generated if biotin is present in the patient’s specimen. Given these considerations, providers need to determine whether their patients are taking biotin supplements, and then let the lab know about it. If a lab test result doesn’t match the patient’s clinical presentation, the provider should consider biotin interference as a possible source of error.
It’s also important that providers report to FDA and the lab test developer if they become aware of a patient experiencing an adverse event due to potentially incorrect lab test results caused by biotin interference.
CLP: And what are FDA’s instructions for clinical laboratorians?
Wonderling: It’s difficult for a lab to pinpoint in advance which of their sometimes thousands of patient samples being tested might contain interfering levels of biotin. Patients may take over-the-counter biotin supplements up to 20 mg per day. For conditions such as multiple sclerosis, physicians may prescribe biotin up to 300 mg per day. Consequently, specimens collected from patients who are taking high levels of biotin may contain anywhere from 100 ng/mL to 1200 ng/mL of biotin.
In light of these complexities, FDA is recommending that all IVD developers investigate each of their assays that employ the biotin-streptavidin technology for biotin interference up to 1200 ng/mL, and to communicate the interference they discover to the clinical lab community.
The FDA safety recommendation also observes that currently available data are insufficient to support recommendations for safe testing using affected tests for patients taking high levels of biotin—or even to support recommendations regarding the length of time needed for biotin clearance from the blood. Therefore, if a lab uses assays based on the biotin-streptavidin technology, it’s very important to communicate that information to doctors and patients, so that incorrect test results and their potential sequelae can be prevented.
Steve Halasey is chief editor of CLP.
- The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication [press release, online]. Silver Spring, Md: FDA, 2017. Available at: www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm586505.htm?utm_campaign=FDA%20Warns%20About%20Biotin%20Interference%20with%20Lab%20Tests&utm_medium=email&utm_source=Eloqua&elqTrackId=9491B149F1419C076FF6918DB60A4A59&elq=a100026055084d2490c3b5f11306949d&elqaid=1526&elqat=1&elqCampaignId=964. Accessed December 4, 2017.
- Kumar A, Roberts D, Wood KE, et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med. 2006;34(6):1589–1596.
- Kummer S, Hermsen D, Distelmaier F. Biotin treatment mimicking Graves’ disease. N Engl J Med. 2016;375(7):704–706; doi: 10.1056/nejmc1602096.
- Trambas CM, Sikaris KA, Lu ZX. More on biotin treatment mimicking Graves’ disease. N Engl J Med. 2016;375(17):1698; doi: 10.1056/nejmc1611875.
- Mardach R, Zempleni J, Wolf B, et. al. Biotin dependency due to a defect in biotin transport. J Clin Invest. 2002;109(12):1617–1623; doi: 10.1172/jci13138.