HIGH-DOSE BIOTIN TREATMENT FOR SECONDARY PROGRESSIVE MULTIPLE SCLEROSIS MAY INTERFERE WITH THYROID ASSAYS

Development and Evaluation of an Anti-Biotin Interference Method in Biotin-Streptavidin Immunoassays

The strong non-covalent interaction between biotin and streptavidin places streptavidin-based assays, used by many laboratories, at an increased risk of interference by biotin. At present, a few manufacturers have developed fully automated anti-biotin interference methods, although compared with many detection platforms, these remain insufficient. Additionally, there is a need for more methods that can achieve fully automated anti-biotin interference. We sought to develop and evaluate a new biotin interference-resisting method based on a biotin-streptavidin chemiluminescence immunoassay. Streptavidin-coated magnetic microparticles (M) of different concentrations were prepared and tested for their biotin-resistance capabilities in an automated setting (Cobas e 601). The precision, accuracy, and detection capability were also assessed. Higher concentrations of M were found to have a stronger ability to resist biotin interference. A 2.16 mg/mL concentration of M was able to resist 500 ng/mL of biotin in samples while simultaneously having a relatively weak shielding effect on the optical signals. Moreover, the total precision and accuracy of this method, designated as M3, met acceptable standards. M3 has an improved ability to resist biotin interference, can achieve full automation, and its detection performance can meet the general laboratory quality requirements.

Mitigation of Biotin Interference in Manual and Automated Immunoassays by Preconjugating Biotinylated Antibodies to the Streptavidin Surface as an Alternative to Biotin Depletion

BACKGROUND

Streptavidin-to-biotin binding is one of the strongest noncovalent interactions in nature and incorporated into many immunoassays. Biotin-streptavidin coupling assays are susceptible to interference from free biotin in patient specimens, which may falsely decrease or increase results. To prevent biotin interference, we evaluated a method to preconjugate biotinylated antibodies to the assay's streptavidin solid surface before adding patient specimen and compared this technique to a biotin depletion protocol.

METHODS

Biotin interference in 3 manual ELISAs and 2 automated immunoassays was established. Mitigation of biotin interference by preincubation was evaluated in each assay by adding biotinylated antibody to the streptavidin-coated surface before adding biotin- or PBS-spiked serum. Lastly, the preincubation method was compared to a biotin-depletion protocol to compare the effectiveness of mitigating biotin interference.

RESULTS

In the presence of 400 µg/L biotin, analyte detection was reduced to 10% to 15% of total in the ELISA assays and to 15.2% in the automated sandwich (thyroglobulin) immunoassay. In the automated competitive (free thyroxine) immunoassay, biotin caused an increased detection of 551.6%. Preconjugation of the biotinylated capture antibody to the streptavidin surface in the ELISA assays resulted in 84% to 99% activity recovery, compared to 84% to 97% by a biotin depletion protocol. Similarly, automated sandwich and competitive immunoassays obtained 97.1% and 116.5% recovery by preconjugation, compared to 95.6% and 100.3% by the depletion method, respectively.

CONCLUSION

This study demonstrates how assay redesign to include preconjugation of biotinylated capture antibody to streptavidin is an effective alternative to biotin-depletion methods to mitigate biotin interference.

AACC Guidance Document on Biotin Interference in Laboratory Tests

BACKGROUND

Laboratory tests that use streptavidin-biotin binding mechanisms have the potential to be affected by high circulating biotin concentrations, which would produce positive and negative interference in biotinylated competitive and noncompetitive (sandwich) immunoassays, respectively. Consumption of high-dose biotin supplements for cosmetic or health-related reasons has drawn attention to biotin interference in clinical laboratory tests. Case reports and in vivo studies show that ingestion of supplemental biotin can cause clinically significant errors in select biotinylated immunoassays.

CONTENT

This AACC Academy document is intended to provide guidance to laboratorians and clinicians for preventing, identifying, and dealing with biotin interference. In vivo and in vitro spiking studies have demonstrated that biotin concentrations required to cause interference vary by test and by manufacturer. This document includes discussion of biotin's mechanisms for interference in immunoassays, pharmacokinetics, and results of in vitro and in vivo studies and cites examples of assays known to be affected by high biotin concentrations. This document also provides guidance recommendations intended to assist laboratories and clinicians in identifying and addressing biotin interference in laboratory testing.

SUMMARY

The recent increase in the use of high-dose biotin supplements requires laboratorians and clinicians to be mindful of the potential for biotin interference in biotinylated immunoassay-based laboratory tests. Laboratories, clinicians, regulators, and patients should work together to ensure accurate laboratory results. Laboratories have several options for identifying suspected biotin interference in specimens. Alternatively, the relatively fast elimination of biotin allows the potential for rapid follow-up specimen analysis if necessary.

Biotin-induced thyroid stimulating hormone aberrations in the setting of immunotherapy

INTRODUCTION

Immune checkpoint inhibitors are associated with immune-mediated thyroid disease and other endocrinopathies. Biotin is an over-the-counter supplement known to interfere with lab assays, including thyroid function tests. Biotin-induced complications with lab monitoring during immunotherapy have not been previously reported.

CASE REPORT

We present a case of a 68-year old woman with hypothyroidism after initiating immune checkpoint blockade therapy and abnormal laboratory monitoring values while concurrently taking biotin supplements.Management & outcome: The patient was initiated on levothyroxine with subsequent dose increases over a period of weeks with resolution of symptoms and normalization of free thyroxine levels. Thyroid stimulating hormone (TSH) levels appeared to remain elevated until biotin supplements were held and levels normalized.

DISCUSSION

The purpose of this report is to provide the first known incidence of biotin complicating the routine monitoring of immune checkpoint inhibitors with elevated TSH levels and to alert providers to elicit accurate medication histories regarding over-the-counter supplements.

Prevalence of Detectable Biotin in Five US Emergency Department Patient Cohorts

BACKGROUND

The objective of this study was to estimate the prevalence of biotin supplementation in United States emergency department patients using a multi-site, geographically distributed sampling model.

METHODS

Biotin was measured using an Abbott ARCHITECT Biotin research use only assay in 7118 emergency department patient serum or plasma samples from five US medical centers. Samples with biotin ≥10 ng/mL underwent additional LC-MS/MS confirmatory testing for biotin and its primary metabolites. The overall and site-specific prevalence of detectable biotin was determined using the screening assay while biotin speciation (i.e., prevalence of detectable metabolites) was determined using LC-MS/MS.

RESULTS

Of 7118 samples screened, 291 (4.1%) had biotin ≥10 ng/mL and were considered positive. Across five medical centers, the fraction of positive samples ranged from 2.0% to 5.4%. The maximum biotin concentration observed was 355 ng/mL. Of the 285 positive screens that underwent additional LC-MS/MS testing, 89 (31%) showed detectable biotin, bisnorbiotin, and/or biotin sulfoxide. Biotin, bisnorbiotin, and biotinsulfoxide were detected in 82/89 (92.1%), 61/89 (68.5%), and 18/89 (20.2%) samples, respectively; biotin was detected in the absence of either metabolite in 18/89 (20.2%) samples.

CONCLUSIONS

Using a screening assay, 4.1% of emergency department patient samples were found to be potentially susceptible to interference from biotin. Confirmatory testing showed detectable biotin and/or biotin metabolites in 31% of positive screens (1.3% overall). The prevalence of biotin ≥10 ng/mL varied 2-3-fold across US emergency department patient cohorts. Biotin metabolites were observed in 80% of samples confirmed to have detectable biotin species by LC-MS/MS, suggesting that rigorous assessments of assay susceptibility to biotin interference, often performed using in vitro studies, should consider the potential role of biotin metabolites present in vivo.

Interference From High-Dose Biotin Intake in Immunoassays for Potentially Time-Critical Analytes by Roche

CONTEXT.—

Immunoassays using the interaction between streptavidin and biotin are used for clinical chemical analytes on platforms by many different manufacturers. The design can be susceptible to interference from high-dose biotin intake in patients, which remains an often-overlooked confounder despite recently increased awareness.

OBJECTIVE.—

To evaluate an easily implementable method of in vitro biotin depletion for the removal of biotin interference in immunoassays for potentially time-critical analytes.

DESIGN.—

A biotin stock solution was made and de-identified patient samples were spiked to reach a biotin concentration of 1.126 × 106 pg/mL, the maximum reported biotin concentration 1 to 2 hours after a single oral dose of 300 mg biotin. Then, the resulting interference in Elecsys immunoassays for cortisol, cyclosporine A, tacrolimus, digitoxin, thyroid-stimulating hormone, free triiodothyronine, free thyroxine, C-peptide, insulin, N-terminal pro-B-type natriuretic peptide, troponin T high sensitive, human immunodeficiency virus, procalcitonin, β human chorionic gonadotropin, toxoplasma immunoglobulin M, and toxoplasma immunoglobulin G was evaluated before and after biotin depletion using streptavidin particles.

RESULTS.—

All tested immunoassays, with the exception of toxoplasma immunoglobulin M and toxoplasma immunoglobulin G, suffered from significant biotin interference. The depletion protocol removed assay interference due to biotin and produced results that were close or identical to initial prespike measurements.

CONCLUSIONS.—

Despite an increase in turnaround times, biotin adsorption is a feasible countermeasure for biotin interference in Elecsys immunoassays. Until test kits with an increased resistance to the interference from high-dose biotin intake are distributed, the evaluated protocol can provide results properly reflecting the patient's clinical condition.

When thyroid labs do not add up, physicians should ask patients about biotin supplements

A 69-year-old woman with a remote history of Graves' disease treated with radioactive iodine ablation, who was maintained on a stable dose of levothyroxine for 15 years, presented with abnormal and fluctuating thyroid function tests which were confusing. After extensive evaluation, no diagnosis could be made, and it became difficult to optimise the levothyroxine dose, until we became aware of the recently recognised biotin-induced lab interference. It was then noticed that her medication list included biotin 10 mg two times per day. After holding the biotin and repeating the thyroid function tests, the labs made more sense, and the patient was easily made euthyroid with appropriate dose adjustment. We also investigated our own laboratory, and identified the thyroid labs that are performed with biotin-containing assays and developed strategies to increase the awareness about this lab artefact in our clinics.

Mitigating biotin interference in two Roche immunoassays by premixing biotinylated capturing molecules with streptavidin coated beads

BACKGROUND

Biotin is an interference in many streptavidin-biotin based immunoassays, causing falsely decreased results with sandwich immunoassays and falsely increased results with competitive immunoassays. It has been discussed that premixing streptavidin coated beads and biotinylated capturing molecules may prevent biotin interference. This study was designed to test whether such modification could mitigate biotin interference in two originally susceptible sandwich immunoassays.

METHODS

Roche C-peptide and human growth hormone (hGH) immunoassays utilize three reagent containers for streptavidin coated beads (M), biotinylated capturing antibody (R1) and ruthenylated antibody (R2). The reagents were modified by premixing reagent M and R1. Following incubation, the beads were placed back in the M-container and R1-supernatant back to R1-container. Patient specimens were selected, spiked with biotin to 1055 ng/mL, and measured by both the original, unmodified reagent and modified reagent on Roche cobas e411 analyzer. The biotin interference dose response curves were also compared using pooled patient specimen spiked with different concentrations of biotin.

RESULTS

For the original reagent, 1055 ng/mL of biotin decreased C- peptide results by 88% and hGH results by 97%. After reagent modification, this interference effect was nearly eliminated for C- peptide but remained about 20% decreased for hGH.

CONCLUSION

Premixing streptavidin beads and biotinylated capturing molecules is an effective approach to mitigate biotin interference for certain immunoassays.

Assessment of biotin interference in thyroid function tests

The aim of the study was to systematically characterize the interference of biotin on thyroid function tests and biotin washout periods.Ten healthy adults were recruited with administration of 5 and 10 mg/d biotin for 7 days. Analyte concentrations of thyroid function tests were measured at baseline prior to starting biotin and from 2 hours to 2 days after withdrawal of 5 and 10 mg/d biotin. The outcomes were compared the baseline with the several points after taking biotin at Roche cobas e602, Beckman UniCel DxI 800, and Abbott Architect 2000 immunoassay platforms, respectively.Ingesting 5 or 10 mg/d of biotin for 7 days could produce positive or negative interference among the thyroid function tests at Roche cobas e602 and Beckman UniCel DxI 800 systems, but no interference on Abbott Architect 2000. Interference duration of 5 mg/d biotin for Roche cobas e602 and Beckman UniCel DxI 800 of thyroid function tests lasted for 8 hours, while 10 mg/d biotin interfered with Roche cobas e602 or Beckman UniCel DxI 800 for 1 day or 2 days.This study provides valuable guidance on biotin washout periods at doses common in over-the-counter supplements necessary to avoid false assay results.Trial registration: ChiCTR1800020472.

Characterization of biotin interference in 21 Vitros 5600 immunoassays and risk mitigation for patient safety at a large academic medical center

BACKGROUND

Biotin and streptavidin are commonly used reagents in clinical immunoassays. Several cases of biotin interference with immunoassay testing for patients taking biotin supplements have been reported, yet, not all analytes and platforms susceptible to biotin interference have been characterized. The objectives of this study are to characterize biotin interference with 21 immunoassays using the Ortho Clinical Diagnostics Vitros 5600, evaluate a biotin-depletion method, and apply risk mitigation strategies for biotin interference during routine clinical testing at our institution.

METHODS

Residual serum without and with increasing concentrations of exogenous biotin were used to evaluate biotin interference with 21 immunoassays using the Vitros 5600. Biotin-depletion was evaluated by comparing measured analyte concentrations in serum with and without exogenous biotin and streptavidin-microparticle pretreatment. Focused education for healthcare professionals about biotin interference was performed in February 2018. Samples with suspected biotin interference were investigated using this biotin-depletion method, and analyte testing by alternate methodology for select samples.

RESULTS

Exogenous biotin in serum caused dose-dependent negative biases in 15 immunometric assays, and dose-dependent positive biases in 6 competitive immunoassays. Streptavidin-microparticle pretreatment of serum containing exogenous biotin demonstrated recoveries 100 ± 15% of expected values for all 21 analytes. Physicians identified 21 samples suspicious for biotin interference over 11 months, and streptavidin-microparticle pretreatment verified 11 cases of biotin interference.

CONCLUSIONS

Analytical bias caused by biotin interference is dependent on biotin concentration but independent of analyte concentration for immunometric methods using the Vitros 5600, and dependent on both biotin and analyte concentration for competitive immunoassays. Multi-disciplinary education and a lab streptavidin-microparticle pretreatment method help mitigate risk of erroneous results due to biotin interference for patient safety.

Aberrant Thyroid Function Tests in a Patient Taking Biotin Supplements

Biotin is a component of the B-complex vitamins that has been widely used in over-the-counter supplements. The effects of biotin on thyroid function tests (TFTs) have been recently reported by multiple authors. We report here a case of a patient who presented with TFTs consistent with hyperthyroidism and a positive radioactive iodine uptake (RAIU) scan while taking biotin supplements. The TFTs normalized almost a month later and continued to be normal even after resumption of biotin supplements. Interpreting TFTs while patients are taking biotin could pose a diagnostic challenge, so we suggest more frequent monitoring for those patients before starting them on long-term anti-thyroid medications. 

How Biotin Induces Misleading Results in Thyroid Bioassays: Case Series

Biotin is widely available over the counter in different doses and is used medically in the management of hair and nail problems. Recent literature suggested the use of high doses of biotin for the treatment of progressive multiple sclerosis. We present four cases that show a misleading increase in thyroid function tests toward a false diagnosis of Grave's disease after the administration of 20-30 mg biotin for different periods. All the four cases are free of the signs and symptoms of hyperthyroidism, and all of their results returned to baseline values within 24-48 hours after biotin withdrawal. The assemblage of these cases, thyroid assay results, and biotin doses had occurred by chance, with no selection bias, and they represented all cases of biotin interference with thyroid assays in our center during this year. The first case is a 23-year-old female who was diagnosed with Grave's disease during a routine checkup after she ingested a prescribed 20 mg biotin per day for three months for excessive hair fall. The second case is a 19-year-old female with hair and nail problems associated with iron deficiency anemia. She administered a self-prescribed biotin dose of 20 mg a day for a month. She asked an endocrinologist's opinion about a recent increase in her thyroid function tests, with no signs of hyperthyroidism. The third case is a 45-year-old man with near-total thyroidectomy for retrosternal multinodular goiter with compressive symptoms. His usual levothyroxine dose had been decreased from 100 to 50 microgram per day, after which he felt unwell and gained four kilograms, with signs and symptoms of hypothyroidism. His investigations were consistent with hyperthyroidism while his signs were of hypothyroidism, which was illogical. He was administered 30 mg medically prescribed biotin for nail changes due to recently diagnosed psoriasis. The fourth case is that of one of the authors who volunteered to take 30 mg of biotin daily for one week. His initial investigations were in the normal range but changed within this period to be Grave's disease-like, with no signs or symptoms. In conclusion, the ingestion of 20 mg or more of biotin may lead to a clinically relevant thyroid assay interference. The clinicians must take this point in consideration before assessing the results of any thyroid function tests.

Susceptibility of Cardiac Troponin Assays to Biotin Interference

OBJECTIVES

To investigate biotin interference on three cardiac troponin (cTn) assays and demonstrate a method to overcome biotin interference.

METHODS

cTn levels were measured in (1) plasma from healthy volunteers on 10-mg daily biotin supplementation mixed with a plasma with known elevated troponin, (2) plasmas with known elevated cTn after mixing in reagent biotin to simulate supplementation, and (3) biotin-spiked plasma specimens pretreated with streptavidin-agarose beads.

RESULTS

Daily biotin ingestion (10 mg) and studies simulating daily biotin use resulted in significant interference in the Gen5 cardiac troponin T (cTnT) assay; the contemporary Gen 4 cTnT and high-sensitivity cardiac troponin I (hs-cTnI) assays were unaffected. The biotin interference threshold was 31, 315, and more than 2,000 ng/mL for Gen5 cTnT, cTnT, and hs-cTnI assays, respectively. Streptavidin pretreatment blocked biotin interference in cTn assays.

CONCLUSIONS

Biotin interference is possible at plasma concentrations achievable by ingestion of over-the-counter supplements that may lead to delayed or missed diagnosis of myocardial injury with the Gen5 cTnT assay.

Versatile Protein-A Coated Photoelectric Immunosensors with a Purple-Membrane Monolayer Transducer Fabricated by Affinity-Immobilization on a Graphene-Oxide Complexed Linker and by Shear Flow

Bacteriorhodopsin-embedded purple membranes (PM) have been demonstrated to be a sensitive photoelectric transducer for microbial detection. To efficiently prepare versatile BR-based immunosensors with protein A as antibody captures, a large, high-coverage, and uniformly oriented PM monolayer was fabricated on an electrode as an effective foundation for protein A conjugation through bis-NHS esters, by first affinity-coating biotinylated PM on an aminated surface using a complex of oxidized avidin and graphene oxide as the planar linker and then washing the coating with a shear flow. Three different polyclonal antibodies, each against Escherichia coli, Lactobacillus acidophilus, and Streptococcus mutans, respectively, were individually, effectively and readily adsorbed on the protein A coated electrodes, leading to selective and sensitive quantitative detection of their respective target cells in a single step without any labeling. A single-cell detection limit was achieved for the former two cells. AFM, photocurrent, and Raman analyses all displayed each fabricated layer as well as the captured bacteria, with AFM particularly revealing the formation of a massive continuous PM monolayer on aminated mica. The facile cell-membrane monolayer fabrication and membrane surface conjugation techniques disclosed in this study may be widely applied to the preparation of different biomembrane-based biosensors.

Interferences With Thyroid Function Immunoassays: Clinical Implications and Detection Algorithm

Automated immunoassays used to evaluate thyroid function are vulnerable to different types of interference that can affect clinical decisions. This review provides a detailed overview of the six main types of interference known to affect measurements of thyroid stimulating hormone (TSH), free thyroxine (T4) and free triiodothyronine (T3): macro-TSH, biotin, antistreptavidin antibodies, anti-ruthenium antibodies, thyroid hormone autoantibodies, and heterophilic antibodies. Because the prevalence of some of these conditions has been reported to approach 1% and the frequency of testing for thyroid dysfunction is important, the scale of the problem might be tremendous. Potential interferences in thyroid function testing should always be suspected whenever clinical or biochemical discrepancies arise. Their identification usually relies on additional laboratory tests, including assay method comparison, dilution procedures, blocking reagents studies, and polyethylene glycol precipitation. Based on the pattern of thyroid function test alterations, to screen for the six aforementioned types of interference, we propose a detection algorithm, which should facilitate their identification in clinical practice. The review also evaluates the clinical impact of thyroid interference on immunoassays. On review of reported data from more than 150 patients, we found that ≥50% of documented thyroid interferences led to misdiagnosis and/or inappropriate management, including prescription of an unnecessary treatment (with adverse effects in some situations), inappropriate suppression or modification of an ongoing treatment, or use of unnecessary complementary tests such as an I123 thyroid scan. Strong interaction between the clinician and the laboratory is necessary to avoid such pitfalls.

Effect of High-dose Biotin on Thyroid Function Tests: Case Report and Literature Review

Biotin is a readily available supplement that is part of the B-complex vitamins. It is an essential co-factor for five carboxylases involved in fatty acid synthesis and energy production. The recommended daily intake (RDI) of biotin ranges from 30 to 70 mcg per day. At high doses (10,000 times RDI), biotin improves clinical outcomes and quality of life in patients with progressive multiple sclerosis (MS). It has been reported to cause interference in immunoassays resulting in abnormal thyroid function tests. Hereby we are describing the case of a patient having MS who was on high-dose biotin, seen in the clinic for a follow-up visit with thyroid function tests suggestive of Graves’ disease with no signs and symptoms of hyperthyroidism and completely normal physical examination. In the case we have described, the laboratory measurements suggestive of thyrotoxicosis were attributed to interference of the patient’s high-dose biotin treatment with the biotin-streptavidin chemistry of the immunoassays. We observed normalization of the thyroid stimulating hormone (TSH) and free T4 measurements when the patient withheld biotin for a week. As our case illustrates, early consideration of biotin interference minimizes unnecessary repeat laboratory studies. As trials in MS are progressing, we expect to see more patients on high-dose biotin treatment with spurious laboratory measurements. Therefore, we advise careful history taking and close communication with the laboratory when the clinical picture does not match with the laboratory results.

Suspected Testosterone-Producing Tumor in a Patient Taking Biotin Supplements

A perimenopausal woman presented with palpitations, hirsutism, and inability to lose weight. Laboratory tests revealed an unusual endocrine hormonal profile including pituitary hormones (TSH, ACTH, and prolactin) below reference intervals and gonadal (testosterone) and adrenal (cortisol) hormones above reference intervals. Ultimately, after a comprehensive workup including a scheduled surgical procedure, abnormal laboratories were determined due to biotin interference. Biotin (vitamin B7) is a water-soluble vitamin and essential cofactor for the metabolism of fatty acids, glucose, and amino acids. The recommended daily intake of biotin for adults is 30 µg/d. Many over-the-counter products, particularly those marketed for hair, skin, and nail growth, contain biotin 100-fold of recommended daily intake. This case is unique due to the abnormalities observed not only in the well-described TSH "sandwich" immunoassay, but also in tests for gonadal steroids, adrenal, and pituitary hormones. Falsely high as well as falsely low results can be ascribed to biotin. Competitive immunoassays (Fig. 1A)- in this case, tests used initially for serum cortisol and testosterone- can demonstrate falsely high results. Interference falsely lowers the immunometric "sandwich" immunoassay (Fig. 1B)-in this case, TSH. Biotin effect on our patient's endocrine testing led to decidedly abnormal findings, unnecessary medical referrals and diagnostic studies, and comprehensible psychological distress. Interference with one immunoassay, TSH, persisted a full 2 weeks after discontinuation of biotin; indeed, some tests demonstrate sensitivity to lesser quantities of biotin. Improved communication between patients, health care providers, and laboratory professionals is required concerning the likelihood of biotin interference with immunoassays.

High dose biotin as treatment for progressive multiple sclerosis

BACKGROUND

Published data suggested high dose biotin improved patients with progressive MS. We wished to determine benefits and side effects of administering daily high dose biotin to patients with progressive multiple sclerosis in a large MS specialty clinic.

METHODS

Forty-three patients with progressive multiple scleroses were prescribed pharmaceutical grade biotin as a single daily dose of 300mg/day. Brain MRIs were performed at baseline and after one year on biotin. Quantitative neurologic exams (EDSS) and blood work monitoring for biotin toxicity were performed at baseline and every three months thereafter.

RESULTS

High dose biotin was safe, and well tolerated, with no evidence of toxicity on blood work and no new lesions on brain MRIs. None of the patients' EDSS scores improved. One-third of patients (38-43%) worsened, most often with increased lower extremity weakness, worsened balance, and more falling, with two patients worsening sufficiently to increase their EDSS scores by 0.5. Several worsened patients improved after stopping biotin.

CONCLUSION

High dose biotin was safe and well tolerated, but of no demonstrable long-term benefit. More than one-third of patients worsened while on biotin, most likely due to their disease, but in some patients also possibly due to the inability of their injured central nervous systems to respond to the increased metabolic demands induced by biotin.

Association of Biotin Ingestion With Performance of Hormone and Nonhormone Assays in Healthy Adults

IMPORTANCE

Biotinylated antibodies and analogues, with their strong binding to streptavidin, are used in many clinical laboratory tests. Excess biotin in blood due to supplemental biotin ingestion may affect biotin-streptavidin binding, leading to potential clinical misinterpretation. However, the degree of interference remains undefined in healthy adults.

OBJECTIVE

To assess performance of specific biotinylated immunoassays after 7 days of ingesting 10 mg/d of biotin, a dose common in over-the-counter supplements for healthy adults.

DESIGN, SETTING, AND PARTICIPANTS

Nonrandomized crossover trial involving 6 healthy adults who were treated at an academic medical center research laboratory.

EXPOSURE

Administration of 10 mg/d of biotin supplementation for 7 days.

MAIN OUTCOMES AND MEASURES

Analyte concentrations were compared with baseline (day 0) measures on the seventh day of biotin treatment and 7 days after treatment had stopped (day 14). The 11 analytes included 9 hormones (ie, thyroid-stimulating hormone, total thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine, parathyroid hormone, prolactin, N-terminal pro-brain natriuretic peptide, 25-hydroxyvitamin D) and 2 nonhormones (prostate-specific antigen and ferritin). A total of 37 immunoassays for the 11 analytes were evaluated on 4 diagnostic systems, including 23 assays that incorporated biotin and streptavidin components and 14 assays that did not include biotin and streptavidin components and served as negative controls.

RESULTS

Among the 2 women and 4 men (mean age, 38 years [range, 31-45 years]) who took 10 mg/d of biotin for 7 days, biotin ingestion-associated interference was found in 9 of the 23 (39%) biotinylated assays compared with none of the 14 nonbiotinylated assays (P = .007). Results from 5 of 8 biotinylated (63%) competitive immunoassays tested falsely high and results from 4 out of 15 (27%) biotinylated sandwich immunoassays tested falsely low.

CONCLUSIONS AND RELEVANCE

In this preliminary study of 6 healthy adult participants and 11 hormone and nonhormone analytes measured by 37 immunoassays, ingesting 10 mg/d of biotin for 1 week was associated with potentially clinically important assay interference in some but not all biotinylated assays studied. These findings should be considered for patients taking biotin supplements before ordering blood tests or when interpreting results.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03034707.

Characterization of the scope and magnitude of biotin interference in susceptible Roche Elecsys competitive and sandwich immunoassays

Background

Biotin interference is a significant problem to which at-risk laboratories must now be attuned. We sought to systematically characterize the nature of this interference in Roche immunoassays.

Methods

Known concentrations of biotin were titrated into serum samples and the effects on competitive and sandwich immunoassays were analysed. The maximum and minimum concentrations examined reflect those likely to be achieved in individuals on 5 to 10 mg supplements at the lower end, and 100 to 300 mg biotin at the high end.

Results

A high variability in biotin tolerance was observed. Some assays, such as troponin T, TSH and antithyroid antibodies, were extremely sensitive to the lower concentrations of biotin (15.6 and 31.3 ng/mL), whereas the majority of assays were relatively resistant. At concentrations ≥500 ng/mL, all assays showed significant interference from biotin but, again, the magnitude of the interference was variable. The more sensitive assays showed profound analytical bias at biotin concentrations that occur with high-dose therapy.

Conclusion

Our data demonstrate high variability in biotin tolerance across Roche immunoassays. The shape of the dose–response curves provides more detailed information than the single manufacturer-quoted figure for biotin tolerance. Accordingly, these data may be used by laboratories for more accurate risk assessment in predicting the effects of biotin. Our data may also be extrapolated to guide timing of blood tests in patients on high-dose biotin therapy: it demonstrates the number of half-lives required to withhold biotin in order to decrease its concentration to below a given assay tolerance.

Depletion of biotin using streptavidin-coated microparticles: a validated solution to the problem of biotin interference in streptavidin-biotin immunoassays

Background Biotin interference in streptavidin-based immunoassays causes widespread analytical distortions that may lead to clinical confusion, inappropriate patient management and, ultimately, adverse events. Its prevalence has increased recently due to the increased use of high-dose biotin therapy in specific patient groups (notably multiple sclerosis) and possibly the general community. Methods We have developed a method to deplete biotin from samples using the streptavidin-coated magnetic microparticles that are a component of most susceptible assays. Results We show that high concentrations of spiked biotin can be adequately depleted from serum using this approach, and that gross biochemical derangements can be restored to normality. We also show that biotin in samples derived from multiple sclerosis patients receiving 300 mg biotin daily can be adequately depleted to remove associated analytical interference and restore normal results. The method is applicable to competitive and sandwich immunoassays and importantly, because it does not change the volume of the sample, suitable for the measurement of free thyroid hormone assays. Application of the method does not significantly change the precision of measurement, and for the majority of analytes, the accuracy is not substantially altered. Conclusions Adopting this method enables laboratories to confirm biotin interference in the appropriate clinical setting. Moreover, it enables laboratories to remove the interference and report accurate and reliable results, without the need for patients to withhold beneficial therapy prior to blood tests. Until the biotin tolerance of susceptible assays is improved, our method gives laboratories a safe alternative for reporting results using streptavidin-based methods.

High-dose biotin therapy leading to false biochemical endocrine profiles: validation of a simple method to overcome biotin interference

Background:

High-dose biotin therapy is beneficial in progressive multiple sclerosis (MS) and is expected to be adopted by a large number of patients. Biotin therapy leads to analytical interference in many immunoassays that utilize streptavidin-biotin capture techniques, yielding skewed results that can mimic various endocrine disorders. We aimed at exploring this interference, to be able to remove biotin and avoid misleading results.

Methods:

We measured free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), parathyroid homrone (PTH), 25-hydroxyvitamin D (25OHD), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, C-peptide, cortisol (Roche Diagnostics assays), biotin and its main metabolites (liquid chromatography tandem mass spectrometry) in 23 plasmas from MS patients and healthy volunteers receiving high-dose biotin, and in 39 biotin-unsupplemented patients, before and after a simple procedure (designated N5) designed to remove biotin by means of streptavidin-coated microparticles. We also assayed fT4, TSH and PTH in the 23 high-biotin plasmas using assays not employing streptavidin-biotin binding.

Results:

The biotin concentration ranged from 31.7 to 1160 µg/L in the 23 high-biotin plasmas samples. After the N5 protocol, the biotin concentration was below the detection limit in all but two samples (8.3 and 27.6 μg/L). Most hormones results were abnormal, but normalized after N5. All results with the alternative methods were normal except two slight PTH elevations. In the 39 biotin-unsupplemented patients, the N5 protocol did not affect the results for any of the hormones, apart from an 8.4% decrease in PTH.

Conclusions:

We confirm that most streptavidin-biotin hormone immunoassays are affected by high biotin concentrations, leading to a risk of misdiagnosis. Our simple neutralization method efficiently suppresses biotin interference.

BIOTIN INTERFERENCE WITH ROUTINE CLINICAL IMMUNOASSAYS: UNDERSTAND THE CAUSES AND MITIGATE THE RISKS

OBJECTIVE

The objectives of this report are to review the mechanisms of biotin interference with streptavidin/biotin-based immunoassays, identify automated immunoassay systems vulnerable to biotin interference, describe how to estimate and minimize the risk of biotin interference in vulnerable assays, and review the literature pertaining to biotin interference in endocrine function tests.

METHODS

The data in the manufacturer's "Instructions for Use" for each of the methods utilized by seven immunoassay system were evaluated. We also conducted a systematic search of PubMed/MEDLINE for articles containing terms associated with biotin interference. Available original reports and case series were reviewed. Abstracts from recent scientific meetings were also identified and reviewed.

RESULTS

The recent, marked, increase in the use of over-the-counter, high-dose biotin supplements has been accompanied by a steady increase in the number of reports of analytical interference by exogenous biotin in the immunoassays used to evaluate endocrine function. Since immunoassay methods of similar design are also used for the diagnosis and management of anemia, malignancies, autoimmune and infectious diseases, cardiac damage, etc., biotin-related analytical interference is a problem that touches every area of internal medicine.

CONCLUSION

It is important for healthcare personnel to become more aware of immunoassay methods that are vulnerable to biotin interference and to consider biotin supplements as potential sources of falsely increased or decreased test results, especially in cases where a lab result does not correlate with the clinical scenario.

ABBREVIATIONS

FDA = U.S. Food & Drug Administration FT3 = free tri-iodothyronine FT4 = free thyroxine IFUs = instructions for use LH = luteinizing hormone PTH = parathyroid hormone SA/B = streptavidin/biotin TFT = thyroid function test TSH = thyroid-stimulating hormone.

A Somewhat Bizarre Case of Graves Disease Due to Vitamin Treatment

Context:

Accurate measurements of circulating hormones is essential for the practice of endocrinology. Immunometric assays employing the streptavidin-biotin system are widely used to measure hormones. However, these assays are susceptible to interference in patients taking biotin supplementations. This interference could mimic a coherent hormone profile, leading to misdiagnosis and unnecessary treatment.

Case description:

The patient, a 32-year-old man with X-linked adrenomyeloneuropathy recently diagnosed with Graves disease, was referred to our department to evaluate his response to antithyroid drugs. His thyroid function tests were still consistent with hyperthyroidism while he had been receiving carbimazole 40 mg/d for 6 weeks. We found no signs of thyrotoxicosis on physical examination despite the “frank and severe” biochemical hyperthyroidism. Noticing that all the patient’s assays had been done at the same laboratory, we suspected assay interference. We therefore repeated the thyroid function tests at our hospital laboratory, which uses a different assay platform. Surprisingly, all the results were normal, confirming assay interference. The patient was taking an investigational “vitamin” therapy, which turned out to be biotin, prescribed at a dose of 100 mg tid as part of a trial of high-dose biotin in X-linked adrenomyeloneuropathy.

Conclusions:

This case should encourage physicians to ask their patients about possible biotin intake, especially when laboratory results are not compatible with clinical findings. If biotin interference is suspected, we propose either using a different assay not based on the streptavidin-biotin system or repeating the analyses after stopping biotin supplementation for one week.

Supplementation with Phycocyanobilin, Citrulline, Taurine, and Supranutritional Doses of Folic Acid and Biotin-Potential for Preventing or Slowing the Progression of Diabetic Complications

Oxidative stress, the resulting uncoupling of endothelial nitric oxide synthase (eNOS), and loss of nitric oxide (NO) bioactivity, are key mediators of the vascular and microvascular complications of diabetes. Much of this oxidative stress arises from up-regulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Phycocyanobilin (PhyCB), the light-harvesting chromophore in edible cyanobacteria such as spirulina, is a biliverdin derivative that shares the ability of free bilirubin to inhibit certain isoforms of NADPH oxidase. Epidemiological studies reveal that diabetics with relatively elevated serum bilirubin are less likely to develop coronary disease or microvascular complications; this may reflect the ability of bilirubin to ward off these complications via inhibition of NADPH oxidase. Oral PhyCB may likewise have potential in this regard, and has been shown to protect diabetic mice from glomerulosclerosis. With respect to oxidant-mediated uncoupling of eNOS, high-dose folate can help to reverse this by modulating the oxidation status of the eNOS cofactor tetrahydrobiopterin (BH4). Oxidation of BH4 yields dihydrobiopterin (BH2), which competes with BH4 for binding to eNOS and promotes its uncoupling. The reduced intracellular metabolites of folate have versatile oxidant-scavenging activity that can prevent oxidation of BH4; concurrently, these metabolites promote induction of dihydrofolate reductase, which functions to reconvert BH2 to BH4, and hence alleviate the uncoupling of eNOS. The arginine metabolite asymmetric dimethylarginine (ADMA), typically elevated in diabetics, also uncouples eNOS by competitively inhibiting binding of arginine to eNOS; this effect is exacerbated by the increased expression of arginase that accompanies diabetes. These effects can be countered via supplementation with citrulline, which efficiently enhances tissue levels of arginine. With respect to the loss of NO bioactivity that contributes to diabetic complications, high dose biotin has the potential to "pinch hit" for diminished NO by direct activation of soluble guanylate cyclase (sGC). High-dose biotin also may aid glycemic control via modulatory effects on enzyme induction in hepatocytes and pancreatic beta cells. Taurine, which suppresses diabetic complications in rodents, has the potential to reverse the inactivating impact of oxidative stress on sGC by boosting synthesis of hydrogen sulfide. Hence, it is proposed that concurrent administration of PhyCB, citrulline, taurine, and supranutritional doses of folate and biotin may have considerable potential for prevention and control of diabetic complications. Such a regimen could also be complemented with antioxidants such as lipoic acid, N-acetylcysteine, and melatonin-that boost cellular expression of antioxidant enzymes and glutathione-as well as astaxanthin, zinc, and glycine. The development of appropriate functional foods might make it feasible for patients to use complex nutraceutical regimens of the sort suggested here.