Description of Event or Problem · 0
I AM REPORTING AN ISSUE WITH THE ROCHE COBAS PTH(PARATHYROID HORMONE) ASSAY. I HAD PARATHYROID SURGERY ON (B)(6) 2023 AT (B)(6). THEY REMOVED ONE PARATHYROID ADENOMA, BUT WHEN THE PTH DID NOT DECREASE ENOUGH AFTER THAT REMOVAL THEY CONTINUED THE SURGERY. THEY ENDED UP REMOVING 3.5 PARATHYROID GLANDS, HALF OF MY THYROID, AND MY THYMUS. THE PTH WAS STILL HIGHER THAN EXPECTED AFTER SURGERY. THEY DISCHARGED ME AND LET ME GO BACK TO (B)(6) AND GET FOLLOW-UP LAB TESTS. I WENT TO (B)(6) FOR THE LAB TESTS AND THE PTH CAME BACK AS UNDETECTABLE. THE SURGEON CALLED ME AND EXPLAINED THEY DETERMINED THAT I HAD ANTIBODY INTERFERENCE WITH THE ROCHE PTH TEST USED AT (B)(6). THE ROCHE COBAS ASSAY FOR PTH WAS INACCURATE FOR ME. THE SURGEON REIMPLANTED PARATHYROID TISSUE FROM MY SURGERY IN MY ABDOMINAL AREA ON (B)(6) 2023. BELOW I HAVE COPIED A LETTER I RECEIVED: THE PURPOSE OF THIS LETTER IS TO INFORM THE HEALTHCARE PROVIDERS OF (B)(6) THAT WE HAVE IDENTIFIED A HETEROPHILE ANTIBODY IN HER PLASMA THAT CAUSES FALSE POSITIVE PTH RESULTS USING THE ROCHE COBAS ASSAY. THE POTENTIAL FOR AN INTERFERING SUBSTANCE WAS BROUGHT TO MY ATTENTION BY (B)(6) ON (B)(6) 2023. HE STATED THAT HE HAD A PATIENT WHO SEEMED TO HAVE INAPPROPRIATELY HIGH PTH CONCENTRATIONS BOTH BEFORE AND AFTER PARATHYROID SURGERY ((B)(6) 2023). PTH HAD BEEN PERFORMED (B)(6) 2023 AT AN OUTSIDE LABORATORY AND RESULTS WERE 137 PG/ML. SHE UNDERWENT PARATHYROID SURGERY ON (B)(6) 2023. HER PTH CONCENTRATIONS DECLINED FROM 84 PG/ML DOWN TO -59 PG/ML AND REMAINED THERE EVEN THE NEXT DAY. THE PATIENT WAS TESTED ON (B)(6) 2023 AT (B)(6) AND HER PTH WAS <6.3 PG/ML (PERFORMED ON SIEMENS ATELLICA). HETEROPHILE ANTIBODY INTERFERENCE WAS INVESTIGATED BY MIXING PATIENT SAMPLE WITH A HETEROPHILE ANTIBODY BLOCKING REAGENT (HBR) FROM SCANTIBODIES INC. AND TESTING WAS PERFORMED ON THE ROCHE ALONG WITH A CONTROL SAMPLE THAT WAS MIXED WITH SALINE. IF RESULTS FROM THE SAMPLE WITH HBR ADDED ARE >50% LOWER THAN WITH SALINE, IT SUGGESTS THAT HETEROPHILE ANTIBODIES ARE PRESENT. THE RESULTS ARE AS FOLLOWS: ROCHE PTH STRAIGHT 55.8 PG/ML ROCHE PTH W/SALINE 42.2 PG/ML ROCHE PTH WITH HBR 6.61 PG/ML THESE RESULTS SUGGEST THAT THIS PATIENT DOES HAVE A HETEROPHILE ANTIBODY THAT IS CAUSING A FALSELY ELEVATED PTH (POSITIVE INTERFERENCE) WITH THE ROCHE METHOD. THE PTH CONCENTRATION IN THE PRESENCE OF HBR WAS CONSISTENT WITH THE <6 OBTAINED AT OUTSIDE HOSPITAL. THE PATIENT SAMPLE WAS SENT TO (B)(6) UNIVERSITY HOSPITAL LABORATORY FOR TESTING ON THE ABBOTT ARCHITECT. RESULTS WERE: ABBOTT ALINITY PTH <4 PG/ML THIS RESULT IS CONSISTENT WITH THE ROCHE PTH ASSAY IN THE PRESENCE OF HBR, AND THE SIEMENS ATELLICA) AGAIN SUPPORTING THE PRESENCE OF HETEROPHILE ANTIBODIES. IT IS OUR RECOMMENDATION THAT THIS PATIENT NOT BE TESTED USING THE ROCHE PTH METHOD IN THE FUTURE. WHILE HETEROPHILIC ANTIBODIES CAN BE TRANSIENT, THEY CAN ALSO PERSIST OR RE-DEVELOP, MAKING INTERPRETATION OF RESULTS FROM THE ROCHE METHOD DIFFICULT IN THIS PATIENT. WE WOULD ALSO LIKE TO POINT OUT THAT WHILE WE HAVE ONLY DETECTED AN INTERFERENCE WITH THIS ONE ASSAY, THIS ANTIBODY COULD POTENTIALLY INTERFERE WITH OTHER IMMUNOASSAYS, INCLUDING ADDITIONAL PTH ASSAYS THAT HAVE NOT BEEN TESTED. PLEASE BE AWARE OF THIS POSSIBILITY IN FUTURE MANAGEMENT OF THIS PATIENT, ESPECIALLY WHEN LABORATORY RESULTS DO NOT APPEAR TO MATCH THE CLINICAL PRESENTATION. WE RECOMMEND CONSULTATION WITH THE LABORATORY MEDICAL DIRECTOR(S) IN THE EVENT OF ANY SUSPECTED DISCREPANCIES. PLEASE DO NOT HESITATE TO CONTACT ME IF YOU HAVE ANY QUESTIONS. SINCERELY, (B)(6).