Access Thyroglobulin

Description of Event or Problem

On 26JUN2026, the customer reported false positive Access Thyroglobulin (Part Number: 33860; Lot Number: 539320) were generated on their DxI 800 Access instrument (Part Number: A71456; Serial Number: (b)(6)). There was a change to patient management reported for two patients. One patient had false positive results reported outside the laboratory and underwent imaging, including ultrasound and uptake scans. There was no report of further harm to the patient as a result of the change in treatment. Note: As two patients were involved, two MedWatch reports will be submitted, one for each patient.The customer elaborated that they had noticed increased positive results and discrepancies with LC-MS, mass spec results. The negativity rate had dropped significantly. The customer stated the questioned results started on (b)(6) 2026 and after retrospective review, the doctor confirmed the two patients which had undergone imaging that they would not have needed otherwise. No other assay or hardware issues were reported in conjunction with this event. Quality Controls were passing within the laboratories established means Calibration passed on (b)(6) 2026, (b)(6) 2026 and (b)(6) 2026 using reagent lot 539320 and calibrator lot 538937. The customer stated no issues with sample integrity as each sample is manually loaded and integrity is checked on each one.

Additional Manufacturer Narrative

A1: The full identifier is (b)(4). A2, A3, A4 and A5: The customer did not provide patient demographics such as age, gender, date of birth, weight, ethnicity or race. H3 and H6: The Access Thyroglobulin reagent was not returned for evaluation. There were no reports of system issues at the time of the event. No hardware errors or flags were reported in conjunction with the event. Calibration and Quality Controls were passing at the time of the event. The customer noted that they received a new reagent lot 633238 on 24-June-2026 and the lot to lot comparison have been much lower by 60% on this new lot 633238 and not matching with previous reagent lot 539320. The customer was sent replacement Thyroglobulin reagent. The customer has not called for any further assistance and were satisfied with the assistance provided. In conclusion, a cause for this event cannot be determined with the available information. There is no evidence to suggest a reagent malfunction was the cause of this event.