The widely used dietary supplement, vitamin B7 or biotin, raised concerns last year. It was found to interfere with some lab tests, prompting the US Food & Drug Administration (FDA) to issue a warning. Such interference is not new to laboratory medicine and will continue to be an issue as new drugs, tests and supplements come to market. And it does not only affect laboratory-based tests, even simple point-of-care glucose metres and pregnancy tests are affected.

But to an increasingly lean laboratory medicine team, interference poses another threat. Following advances in automation and big data analysis, many labs today can run a full day-to-day volume of various chemistry samples with just two laboratory scientists manning the line. But when a call back comes because of an unusual result, this carefully honed operating model is challenged, upsetting the downstream testing process. In that team of two, one would have to troubleshoot, affecting the team’s ability to report urgent values or handle priority samples from patients with life threatening health concerns.

While interference cannot always be predicted, there are plenty of areas where it can be prevented. Here are three steps to mitigate the impact of preventable interference such as that caused by biotin to help lab teams remain efficient and effective.

Step 1: Education of providers and patients

As laboratory medicine experts, it is our duty to step outside the laboratory and educate our customers – whether that is the patient or his care provider. Through presentations to physicians at hospital Grand Rounds, conferences or even blog posts and email alerts, we need to build partnerships and understanding to support the dissemination of knowledge.

At UC Davis, we launched a laboratory best practice blog [1] about two years ago. Aimed at providers, we post one entry a month covering important topics, such as interference. But we must not forget the patient. In the case of biotin or other preventable sources of interference, we need to educate patients about how to prepare for their test, through means such as instructional leaflets or reminders.

Step 2: Surveillance

The second strand is surveillance. To ensure the right educational efforts are put in place, it is paramount to understand what a lab’s local population or even national population looks like. For example, is biotin actually a common supplement in that population and in doses that are likely to be detectable? Compiling data from a lab’s own records as well as databases such as the FDA’s Manufacture and User Facility Device Experience (MAUDE) [2] helps to build that picture.

For example in the case of biotin use, the MAUDE database shows that the vast majority of tests that threw up biotin interference involved patients with multiple sclerosis. These patients would be taking in excess of 100 mg of biotin per day in an off-label use of the supplement. However, this is something that laboratory team together with care teams can probe for during history taking and plan for when scheduling tests.

At UC Davis, we went a step further as we wanted to find out whether biotin interference was likely in our patient population. We examined the electronic health records of more than 800 patients and determined that none of the patients had concentrations of biotin that approached the level where it would interfere with the assay.

However, following the FDA’s alert that biotin could interfere with troponin measurements, we conducted a multi-centre review of 1,443 samples from 850 patients. We found that biotin levels were detected in fewer than half of them. Again, this reassured us that biotin interference is likely to be highly uncommon in our patient population, despite the media headlines.

Step 3: Proactiveness

The last prong is to take a proactive stance to manage potential interferences before they affect laboratory processes. At UC Davis, have evaluated an electronic early warning into our system. This alerts the provider and the lab that the test ordered could be affected by biotin interference. However, we have to be aware that such alerts are often ignored as data has shown that almost three in four medication-related electronic health system alerts are overridden by the user. This, therefore, cannot be the only strategy, but it can serve as a last line of defence.

Mitigating the disruption caused by preventable interference requires an integrated, evidence-based strategy. Understanding the patient population is key to assessing the likelihood of a given substance’s interference in laboratory testing. Some interference such as heterophile interference cannot be predicted or prevented. But where interference can be prevented, it is crucial that we in laboratory medicine proactively support the physicians and patients with the right education to ensure that it is prevented. As with all aspects of healthcare, prevention is always better than treatment.

[1] “UC Davis Health Lab Best Practice” https://health.ucdavis.edu/blog/lab-best-practice

[2] “MAUDE – Manufacture and User Facility Device Experience”, US Department of Health and Human Services

This article is based on the presentation: Immunoassay interferences: Facts, insights and a pragmatic approach at the Roche Efficiency Days (RED) 2018 REDefining perspective in Guangzhou, China.