Biotin interference in routine IDS-iSYS immunoassays for aldosterone, renin, insulin-like growth factor 1, growth hormone and bone alkaline phosphatase.

Biotin is increasingly used as dietary supplement. As many immunoassays rely on a binding between biotin and streptavidin, intake of biotin may interfere with laboratory tests, leading to spurious test results. We examined the extent to which levels of aldosterone, renin, insulin-like growth factor 1 (IGF-1), growth hormone (GH) and bone alkaline phosphatase (BAP) were affected by biotin. In an experimental study performed at Aarhus University Hospital, Denmark, patient samples (plasma or serum) were pooled and spiked with biotin in increasing concentrations (0, 20, 50, 100 and 500 ng/mL). All biomarkers were analyzed using Immunodiagnostic Systems (IDS-iSYS) Multi-Discipline Automated System assays. The average bias (%) was calculated, as the difference in concentrations between the sample without biotin (reference) and the samples with increasing concentrations of biotin. Both aldosterone and renin assays showed substantial biotin interference in a dose-dependent manner, with biases up to +3484% for aldosterone and -98% for renin in the highest concentrations of biotin (100-500 ng/mL). IGF-1, GH and BAP results were generally less affected by added biotin and significant bias (>10%) was observed only when the biotin concentration was 100 ng/mL (IGF-1 and GH) or 500 ng/mL (BAP). In conclusion, biotin interfered with the IDS-iSYS immunoassays, particularly for aldosterone and renin. The assays for GH, IGF-1 and BAP were less sensitive and only with high concentrations of biotin.