MSACL 2024 Abstract

Introduction
In recent years, as fewer laboratories offer testing for rare diseases, we have seen an increase in requests for acute porphyria screening. Traditional assessment of urine for acute porphyria entails measurement of porphobilinogen (PBG) by reaction with Ehrlich’s reagent (p-dimethylamino-benzaldehyde) followed by spectrophotometric detection. This manual method is insensitive, relatively nonspecific, labor intensive and subject to interference from unknown urine constituents. To improve detection of PBG in urine specimens, we developed, validated, and implemented a new LC-MS/MS assay. Method development and validation are described in a separate submission (first author Kushnir). Here, we detail the process of implementing the new assay in the clinical laboratory through collaboration of laboratory, R&D, and IT staff.

Methods
In our laboratory, clinical laboratory staff work closely with R&D scientists during method development, optimization, and assay improvements. Method development and validation conclude with review and approval of the validation data and report, and a draft protocol as well as submission of the new method to regulatory bodies for approval, if necessary. After the method validation is complete, formal transfer of the test to the laboratory is initiated. A designated laboratory staff person works with the R&D scientist and laboratory management to design a formal plan to transfer the test into the laboratory for implementation into routine clinical use. Test transfer and method performance evaluation consist of a series of studies performed to assess the assay’s performance and to ensure a smooth transition. Initially, the scientist trains the staff person to perform the assay. Training run data are used to determine proficient performance and robustness of the assay. Quality control (QC) ranges are established, and a supply chain and ordering schedule are created based on anticipated test volume. Transition test results must meet acceptance criteria derived from the method development and the primary validation studies. After all studies have been completed successfully (producing results that satisfy the predetermined acceptance criteria), performance of the assay is considered acceptable, and the test is ready for use. Numerous departments are involved in test transition and implementation. Reagent production, material control, and information technology are involved in testing logistics, and the business operations team updates test information and customer interface details. The laboratory staff liaison is responsible for reviewing and revising the test protocol and training additional laboratory staff to perform the assay. In addition, the liaison creates training modules and works with the education department to assess training and competency of the staff personnel involved in routine testing. Finally, a go-live date is set, and the new test is implemented.

Results
The new LC-MS/MS method uses significantly smaller specimen volume and simplified sample preparation as well as a shorter analysis time. Sample preparation is performed in a 96-well plate format and automated techniques are employed for result review and data management. These changes required validation of several laboratory-developed software tools during assay transfer and implementation. Verification studies for method, instrument, and software applications, and staff training and competency assessment were completed. Data from the method validation and assay transfer demonstrated that the test was sufficiently robust for routine clinical diagnostic use. As part of assay implementation, QC ranges were established, preparation and delivery of reagents and supplies were scheduled and changes to the test directory were submitted.

Conclusions
As compared to the method that was previously in use, the new method has more appropriate performance characteristics, is streamlined, and easier for technologists to perform. Subjective evaluation of visible spectra has been replaced with objective measurement of PBG, afforded by LC-MS/MS analysis, and resulting in elimination of occasional interferences. Testing efficiency was optimized through use of a 96-well plate format, assay standardization, automation, use of an LIS interface, and software applications for data transfer and the results review process. This method has increased clinical specificity and sensitivity and reduced the reagent and laboratory supply cost. Laboratory staff training was successful; the assay was implemented, has adequate performance and provides faster turnaround time.