Lab specialists are bombarded by warnings aimed at preventing diagnostic errors or test interference, and with good reason—errors are common in healthcare. However, laboratories boast lower error rates than clinical healthcare [1]. Most errors that do occur (46-68.2% of them) are pre-analytic, such as order entry errors, getting an insufficient sample volume, or labeling the sample incorrectly. Another 18.5-47% take place after the test is done (for example, failing to report the result). Only 7-13% of all laboratory errors are analytical in nature.

Of the three main phases during which problems can occur in laboratory testing, analytic errors—including test interference—are believed to be the rarest.

Some of the most common causes of interference in blood testing are due to pre-analytic issues, such as the haemolysis of a sample—the most common reason why specimens are rejected. This problem alone can cause falsely increased results on at least a dozen lab tests, and falsely decreased results on at least five tests. Lipemic (excessive fat levels) and icteric (high levels of bilirubin) samples can be similarly problematic [2].

It is critical that these key sources of interference are identified and understood. But just for good measure (and good quality), it is important that laboratory specialists familiarise themselves with less common causes of interference, such as biotin.

Biotin’s infamy

Following a series of peer-reviewed journal articles documenting biotin interference with lab tests, the US Food and Drug Administration issued a warning in late 2017 on the topic [3]. The agency hoped to improve safety and testing quality by raising awareness after numerous cases of incorrect lab test results occurred among people taking biotin at high levels.

In some patients, biotin interference can be quickly identified, since it may be prescribed in very large doses to treat conditions such as multiple sclerosis, although this disease is rare in many countries in Asia and the Pacific. Biotin is also the standard treatment for biotinidase deficiency, a rare condition worldwide.

In other patients, a high intake of biotin can be difficult to discover, as some people may not even know they take it.

Biotin is a water-soluble vitamin, also known as vitamin B7 or vitamin H. It can be found in prenatal vitamins, daily multivitamins, and dietary supplements to improve the hair, nails, liver, nervous system, and skin. In all of these products, biotin may be present at levels high enough to interfere with lab tests. Doses of 5mg per day or more can cause interference with results; some patients may take doses ranging from 20mg to 300mg per day [3].

Depending on the type of test performed, excess biotin in the blood can lead to either falsely high or falsely low results. Misleading results can be particularly worrisome when they conceal a life-threatening health problem, such as a heart attack. They can also result in unnecessary diagnostic testing and inappropriate medical care.

How can labs address biotin interference?

In a perfect world, physicians or phlebotomists would ask every patient getting a lab test whether they take biotin in vitamins or supplements, at levels of 5 mg per day or higher. In reality, labs are fortunate if anyone knows about a patient’s biotin intake (including the patient).

While this can be a cause for concern, it’s not a cause for panic. Prepare your team to manage possible biotin interference as you would any other sample-related interference.

• Educate the healthcare providers you work with. Let them know that biotin doses at or above 5 mg/day can interfere with results, and that these doses can be found in many vitamins and supplements.
• Ask physicians, nurses, and phlebotomists to inform you if a sample may be impacted. Alternatively, they should instruct patients taking biotin to wait at least 8 hours after a biotin dose before getting their blood drawn for the lab tests.
• Consider posting an educational flyer in your laboratory waiting room about biotin interference and common types of products that may contain biotin. Ask patients to inform sample collection staff if they use such products, prior to the blood draw.
• Educate laboratory staff that patients taking high biotin doses may have high levels of biotin in their blood, such as 100 to 1200 ng/mL. High levels should prompt lab members to ask the physician about the patient’s biotin status and whether the test should be repeated after biotin clearance.
• When physicians or laboratory staff notice that lab results do not line up with expectations based on a patient’s clinical presentation, biotin should be considered among the possibilities for interference.

Remember: Biotin isn’t the only potential laboratory pitfall

It is rare for patients to take biotin at levels that interfere with laboratory results. When put into context with other possible errors or interferences, biotin is a relatively minor problem.

While it is important and feasible to consider biotin as a possible source of interference, it is much more likely that other preventable quality control problems—such as improper specimen collection or transport procedures—are impacting your lab’s results to a greater degree. By identifying and focusing on the primary sources of errors under your control, you can impact more patients and improve your lab’s accuracy.

[1] Hammerling, A, J. (2012). “A review of medical errors in laboratory diagnostics and where we are today.” Laboratory Medicine, 43(2),pp.41-44.

[2] Test affected by hemolysed, lipemic and icteric samples and their mechanism. https://laboratoryinfo.com/tests-affected-hemolyzed-lipemic-icteric-samples-mechanism/

[3] The FDA warns that biotin may interfere with lab tests: FDA Safety Communication. https://www.fda.gov/medical-devices/safety-communications/fda-warns-biotin-may-interfere-lab-tests-fda-safety-communication

This article is based on a presentation: Pitfalls in the Interpretation of Laboratory Tests at Roche Scientific Days 2018: Empowering Lab Leadership to the Next Level in Dusit Thani Hua Hin, Thailand.