Factitious Graves' Disease Due to Biotin Immunoassay Interference—A Case and Review of the Literature

Abstract

Biotin ingested in moderate to high doses can cause immunoassay interference. Depending on the assay format, biotin interference can result in either falsely high or low values. Interference is not limited to thyroid tests and has the potential to affect a wide range of analytes. It is important for clinicians to be aware of this interaction to prevent misdiagnosis and inappropriate treatment.

False biochemical diagnosis of hyperthyroidism in streptavidin-biotin-based immunoassays: the problem of biotin intake and related interferences

“…a thyrotoxic biochemical profile in a patient who is clinically euthyroid. The anomaly may extend to several other endocrine investigations to heighten suspicion of assay interference [3].…”

“…However, when facing very high concentration of biotin in multiple sclerosis, almost every competitive and sandwich assay will be equally dramatically artifacted, as evidenced in recent case reports [2,3] (Table 3). When multiple immunoassays are prescribed and assayed using the same streptavidin-biotin methodology, many other erroneous results are to be expected: it may be useful to look for falsely lowered (sandwich assays) and falsely increased concentrations (competitive assays).…”

“…When multiple immunoassays are prescribed and assayed using the same streptavidin-biotin methodology, many other erroneous results are to be expected: it may be useful to look for falsely lowered (sandwich assays) and falsely increased concentrations (competitive assays). Some other analytes concentrations are likely to be erroneous, for as many as 12 assays demonstrating interference have been reported in one recent case involving biotin megadose, in sandwich as well as competitive assays [3].…”

“…No accumulation of biotin in blood is expected in case of repeated administration [15]. Elston et al observed a normalization of the FT4 result 3 days after cessation of 300 mg biotin administration [3]. The time needed to recover a biotin concentration compatible with the other tests is not known.…”

“…This is related to the two different assay formats in use in immunoassays, in which inhibition of immune complexes separation, whatever the cause, will lead to opposite erroneous results. This opposite impact may mimic an endogenous endocrine pathological condition, and lead to a seemingly consistent biochemical diagnosis of hyperthyroidism [1][2][3], as well as vitamin D intoxication [4], or parathyroid hormone (PTH) suppression [5]. Some new therapeutic protocols involving high doses of biotin (300 mg) in neurology have very recently attracted our attention to this problem [1][2][3]6].…”