The investigation determined that lower than expected vitros tsh results were observed when processing samples drawn on different days obtained from one patient on a vitros 5600 integrated system.The likely assignable cause of the event is an interferent causing the lower than expected vitros tsh results.As per the ortho medical safety officer, the patient has consistently low tsh but normal ft4, given that this patient takes 10 mg/day biotin, it is very likely the lower than normal tsh results were due to biotin interference, and the impact to the tsh results could be dependent on the biotin level in the patient¿s circulation at the time of the draw.Per the tsh instructions for use, ortho has not quantified the interfering effect of biotin on the tsh assay at biotin concentrations >0.5 ug/dl.However, on 14 february 2018 ortho issued customer letter ¿information on how biotin may affect specific vitros microwell assays¿ to alert customers of the effect high-dose biotin supplements have on some vitros immunodiagnostics products (microwell assays) such as the vitros tsh assay.The vitros tsh assay includes the use of streptavidin-biotin in the design which may be susceptible to biotin interference.Therefore, the lower than expected vitros tsh results obtained is likely caused by biotin interference.There is no evidence that a vitros tsh reagent issue or a vitros 5600 system issue contributed to the lower than expected vitros tsh results.
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A customer observed consistently lower than expected vitros tsh results obtained from multiple sample draws from the same patient.The vitros tsh results were all considered hyperthyroid when corresponding vitros ft4 results obtained from the same samples were all considered euthyroid.The vitros tsh and ft4 results from each sample are summarized below.(b)(6).The true tsh value for each sample draw is unknown, however as the vitros tsh values are consistently below the reference interval (hyperthyroid) and the vitros ft4 results are consistently within the reference interval (euthyroid), ortho as conservatively decided to report this event.A lower than expected tsh result of the magnitude described above may lead to inappropriate medical action if not detected.It is unknown if the lower than expected, vitros tsh results were reported from the laboratory.However, ortho was not made aware of any allegation of patient harm as a result of this event.(b)(4).
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