Giuseppe Lippi^1,2, Graziella Bonetti^1,3, Annalisa Modenese^1,4, Andrea Padoan^1,5, Davide Giavarina^1,6, per il GdS SIBioC sulla Variabilità Extra-Analitica (SIBioC-VEA)
¹Gruppo di Studio sulla Variabilità Extra-Analitica (SIBioC-VEA)
²Sezione di Biochimica Clinica, Azienda Ospedaliera Universitaria Integrata di Verona, Verona, Italia
³Laboratorio Centrale di Chimica Clinica, ASST – Spedali Civili, Brescia, Italia
⁴Istituto Clinico Città Studi (ICCS) Milano, Italia
⁵Dipartimento Strutturale Medicina di Laboratorio, Azienda Ospedale Università di Padova, Italia
⁶Dipartimento della Diagnostica, Laboratorio Analisi, Ospedale San Bortolo, Vicenza, Italia

Biotin is a water-soluble vitamin, which participates to a vast array of metabolic pathways involving fatty acids, carbohydrates and amino acids metabolism. This vitamin is also capable to form high-affinity bonds with various molecules, including streptavidin and avidin, which are essential components of many nimmunoassays based on the principle of biotin-streptavidin or biotin-avidin binding. In patients assuming high doses of biotin, therefore, some competitive and non-competitive immunoassays may exhibit falsely increased and falsely decreased test results, respectively, with magnitude of interference depending on biotin concentration in the test sample and on specific vulnerability of the immunoassay. With the aim to provide some expert guidance for identifying, preventing and managing biotin interference in clinical laboratory practice, this document contains a series of consensus recommendations endorsed by the Working Group on Extra-Analytical Variability of the Italian Society of Clinical Chemistry and Clinical Molecular Biology (SIBioC). Briefly, the most important recommendations encompass local evaluation of possible biotin interference, routine history taking on biotin intake for both inpatients and outpatients, informing clinicians on potentially biotin-sensitive immunoassays, sample retesting 24-48 hours after the last biotin administration, along with possible consideration to add a note in the laboratory report highlighting the methods more vulnerable to biotin interference. Routine biotin measurement in all samples is currently discouraged.