Excess biotin may cause false-negative results in allergen-specific IgE testing

An excess of biotin can result in false-negative allergen-specific IgE results during the one-step biotin-streptavidin-based IMMULITE-2000 assay, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.

Clinicians should then be aware of medication or dietary history involving biotin, also known as vitamin B7, before allergen-specific IgE testing, Markus Ollert, MD, DMSci, director of the department of infection and immunity at Luxembourg Institute of Health in Esch-sur-Alzette, Luxembourg, and colleagues wrote in the study.

In adults, plasma biotin concentrations normally range from 0.1 ng/mL to 0.8 ng/mL; however, over-the-counter and prescription biotin-rich supplement use has increased substantially among the general adult population in the United States, according to the researchers.

Allergy diagnoses use biotin-based immunoassays to detect sIgE, but biotin concentrations of 5 ng/mL and above can falsely depress sIgE results on the two-step 3gAllergy IMMULITE-2000 (Siemens Medical Solutions) platform, the researchers wrote.

To test potential interference, the researchers spiked sera with biotin concentrations of 300 ng/mL to 1,200 ng/mL, which are similar to what has been observed after higher doses of biotin due to food supplements or medication.

First, the researchers measured the sIgE levels in the sera of 14 patients who had been sensitized to inhalation allergens, with sera from the same patients that had only received diluent used as a control.

The researchers stratified patients based on lower (n = 5), intermediate (n = 4) or higher (n = 5) sIgE levels for each allergen. They also compared the 3gAllergy IMMULITE-2000 platform with the one-step NOVEOS (Hycor) biotin-streptavidin-based diagnostic platform and with ImmunoCAP (ThermoFisher Scientific), which does not use biotin-streptavidin.

Biotin did not interfere with sIgE readouts from the NOVEOS and ImmunoCAP assays regardless of the patients’ sIgE levels, the researchers found. But 300 ng/mL of biotin reduced sIgE signals on the IMMULITE-2000 platform (mean ± standard deviation, 92% ± 6.1%).

All of the low sIgE samples yielded false-negative results at the 0.35 kU/L threshold, with three of five samples negative at the 0.1 kU/L threshold.

Half of the samples with intermediate sIgE levels tested negative at 300 ng/mL and 600 ng/mL of biotin at the 0.35 kU/L threshold, and all samples were affected at 1,200 ng/mL of biotin, but only one sample was false-negative at the 0.1 kU/L threshold.

Biotin affected sera with higher sIgE levels through a lowered sIgE result, but not in regard to a positive or negative test result, the researchers wrote, adding that biotin interference was independent of the sIgE allergen specificity as well.

In the second part of the study, the researchers investigated biotin-streptavidin reactions among 18 patients with a history of anaphylaxis, including six cases following cashew ingestion, six cases following peanut ingestion and six cases following a sting from a yellow jacket.

The sIgE readouts in the IMMULITE-2000 assays dropped by a mean of 86% after 184 ng/mL of biotin was added and by a mean of 92% after 500 ng/mL of biotin was added. Also, five of the six patients allergic to cashew had false-negative results at both doses at the 0.35 kU/L threshold.

Further, 184 ng/mL of biotin caused false-negative results in three of the six patients allergic to yellow-jacket, whereas 500 ng/mL caused false negatives in four of these patients.

Half of the patients allergic to peanut experienced false negatives with 184 ng/mL doses, and the higher dose elicited false negatives in five of these patients.

Both doses significantly interfered with sIgE values among these 18 patients, the researchers wrote. However, the NOVEOS assay did not register any effect from the tested biotin concentrations in any of the 18 anaphylactic patients.

The researchers cautioned that laboratories and clinicians that use the IMMULITE-2000 assay need to be aware of their patients’ medication and dietary history as it relates to biotin intake before sIgE testing.

Also, the researchers recommended that these patients discontinue biotin for 3 or 4 days before testing. When medical reasons prevent discontinuation, the researchers advised that mitigation strategies are available to circumvent the interference.

Finally, the researchers said that future studies should analyze the sera of patients with allergies at different time intervals after biotin supplements have been administered orally.