Biotin Interference With Routine Clinical Immunoassays

Understand the Causes and Mitigate the Risks

Shanika Samarasinghe, MD; Farah Meah, DO; Vinita Singh, MD; Arshi Basit, MD; Nicholas Emanuele, MD; Mary Ann Emanuele, MD; Alaleh Mazhari, DO; Earle W. Holmes, PhD


Endocr Pract. 2017;23(8):989-998. 

In This Article

Abstract and Introduction


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.

Introduction and Relevance of Issue

Biotin is a water-soluble B-complex vitamin with multiple roles in a variety of metabolic pathways.[1,2] It is a small molecule that can be covalently coupled to proteins, polypeptides, and low-molecular weight antigens including thyroid and steroid hormones with minimal effects on the biological and antigenic activities of the products, thus enabling the use of biotin conjugates as ligands in competitive and immunometric assay formats.[3] Consequently, avidin/biotin chemistries have played a significant role in the development of the field of clinical immunoassay over the past 25 years and have been incorporated into many of the immunoassay methods that are currently used for patient care.[4]

Supraphysiologic biotin supplementation is increasingly marketed in the United States as an over-the-counter remedy for common hair and skin problems, as well as beneficial for weight loss, enhancing glucose metabolism, and boosting energy. Pharmacologic use of biotin includes inherited metabolic diseases such as genetic biotin deficiency and biotin-thiamine responsive basal ganglia disease. It is also used as supportive treatment in patients with disorders of mitochondrial energy metabolism.[5] High-dose biotin has also been recently studied in progressive multiple sclerosis,[6] for use in alleviating muscle cramps in hemodialysis patients,[7] and in patients with malabsorption syndromes or in total parenteral nutrition.[8]

Biotin is available over the counter in doses up to 100 mg, mega doses that greatly exceed the requirements of 30 mcg per day. In fact, 15 to 20% of individuals in the U.S. report consuming biotin-containing dietary supplements.[9,10] There are favorable tolerability and safety profiles in individuals that received pharmacological doses of up to 300 mg a day. Many may not consider it a medication and worth reporting to their physician. Unfortunately, this marked increase in the use of biotin has led to an increase in the risk of clinically significant analytical errors in subjects that use high-dose biotin supplements. This can result in misdiagnosis and potential inappropriate treatment.[5,11] The purpose of this review is to provide an awareness of potential biotin interference that can falsely increase or decrease results for a variety of routine immunoassays. This includes thyroid, steroid and polypeptide hormones, tumor markers, vitamins, and infectious disease serologies.[5] This review will detail the mechanisms of analytic interference utilizing streptavidin/biotin (SA/B) methodology. We also examine the product labeling for popular immunoassay systems in use in the United States in order to assess the risk of biotin interference in vulnerable immunoassays. Finally, a summary of the clinical literature is presented with an emphasis on hormonal immunoassays.