Lot verification practices in Ontario clinical chemistry laboratories - Results of a patterns-of-practice survey.

Objectives: Verifying new reagent or calibrator lots is crucial for maintaining consistent test performance. The Institute for Quality Management in Healthcare (IQMH) conducted a patterns-of-practice survey and follow-up case study to collect information on lot verification practices in Ontario. Methods: The survey had 17 multiple-choice questions and was distributed to 183 licensed laboratories. Participants provided information on materials used and approval/rejection criteria for their lot verification procedures for eight classes of testing systems. The case study provided a set of lot comparison data and was distributed to 132 laboratories. Responses were reviewed by IQMH scientific committees. Results: Of the 175 laboratories that responded regarding reagent lot verifications, 74% verified all tests, 11% some, and 15% none. Of the 171 laboratories that responded regarding calibrator lot verifications, 39% verified all calibrators, 4% some, and 57% none. Reasons for not performing verifications ranged from difficulty performing parallel testing to high reagent cost. For automated chemistry assays and immunoassays, 23% of laboratories did not include patient-derived materials in reagent lot verifications and 42% included five to six patient materials; 58% of laboratories did not include patient-derived materials in calibrator lot verifications and 23% included five to six patient materials. Different combinations of test-specific rules were used for acceptance criteria. For a failed lot, 98% of laboratories would investigate further and take corrective actions. Forty-three percent of laboratories would accept the new reagent lot in the case study. Conclusion: Responses to the survey and case study demonstrated variability in lot verification practices among laboratories.

Survey of renin and aldosterone testing practices by Ontario laboratories - Providing insight into best practices.

OBJECTIVES: Testing for renin and aldosterone in clinical laboratories is complicated by pre-analytical considerations such as the posture for blood collection and susceptibility to cryoactivation of renin. From an analytical perspective, there are both renin activity and renin mass or concentration assays available. There can also be variability in result reporting practices and the aldosterone-renin ratio (ARR) cut-off applied to screen for primary aldosteronism (PA). The Institute for Quality Management in Healthcare (IQMH) Centre for Proficiency Testing surveyed laboratories on their handling of renin and aldosterone testing to better understand current practices. DESIGN AND METHODS: An online survey was prepared and sent to 134 Canadian laboratories enrolled in endocrinology proficiency testing with IQMH. RESULTS: One hundred twenty Ontario laboratories submitted responses. While only six (5%) laboratories perform testing for both renin and aldosterone, 108 (90%) collect and process specimens to be tested by reference laboratories. The survey revealed considerable variation in practices including the recommended state of patients prior to sample collection (for example, regarding medications or salt intake), the patient posture specifications for sample collection, the precautions taken against cryoactivation of renin, the choice of renin activity or mass assay, and the ARR cut-off used. The available literature on these factors was then reviewed. CONCLUSIONS: Although there is no standardized procedure for specimen collection, analysis, or result reporting for renin or aldosterone testing, we have attempted to summarize the available literature to develop evidence-based recommendations. Where laboratory practice differs from peers and/or recommended protocols, laboratories should review their practices.

Analytical measurement and clinical relevance of vitamin D(3) C3-epimer.

With an ever-increasing clinical interest in vitamin D insufficiency, numerous automated immunoassays, protein binding assays, and in-house LC-MS/MS methods are being developed for the quantification of 25-hydroxyvitamin D(3) (25(OH)D(3)). Recently, LC-MS/MS methods have identified an epimeric form of 25(OH)D(3) that has been shown to contribute significantly to 25(OH)D(3) concentration, particularly in infant populations. This review describes the metabolic pathway and physiological functions of 3-epi-vitamin D, compares the capability of various 25(OH)D(3) methods to detect the epimer, and highlights recent publications quantifying 3-epi-25(OH)D(3) in infant, pediatric, and adult populations. In total, this review summarizes the information necessary for clinicians and laboratorians to decide whether or not to report/consider the C3-epimer in the analysis and clinical assessment of vitamin D status.

Standardized Procedural Practices of the Ontario Prenatal Screening Program for aneuploidies and open neural tube defects.

BACKGROUND/OBJECTIVES: The Ontario Prenatal Screening Program (OPSP) follows internationally recognized standardized procedures for laboratories and genetics clinics. However, it has been found that some procedures are subject to interpretation, so the current procedures are designed to facilitate a unified approach in the interpretation of literature recommendations. In Ontario, the OPSP offers multiple screening modalities with integrated prenatal screening (including both first and second trimester markers) being the most commonly chosen option. Other screening modalities include first trimester screening, second trimester quad screening, serum integrated screening, and NT-Quad. METHODS: The standardization was based on a literature review and on current practices in Ontario. RESULTS/DISCUSSION: The main finding of the review was a paucity of published data relating to the procedures and the decision-making processes involved in prenatal screening. The purpose of this publication is to provide the most up-to-date and pertinent information for clinical laboratory professionals involved with prenatal screening for Down syndrome, trisomy 18 and open neural tube defects.

Reporting of post-polyethylene glycol prolactin: precipitation by polyethylene glycol 6000 or polyethylene glycol 8000 will change reference intervals for monomeric prolactin.

BACKGROUND: When screening for macroprolactin, many laboratories use precipitation by polyethylene glycol (PEG) with molecular weight 6000 (PEG6000) or 8000 (PEG8000), and report the percentage prolactin recovery. It has been proposed that reporting of percentage prolactin recovery should be replaced by absolute post-PEG prolactin; however, the post-PEG prolactin reference interval has been established using PEG6000 only. We sought to determine whether the use of PEG8000, instead of PEG6000, changed post-PEG prolactin concentrations. METHODS: We compared the post-PEG6000 and post-PEG8000 prolactin concentrations in hyperprolactinaemic serum samples referred for macroprolactin screening (n=40), using Passing-Bablok regression analysis and Bland-Altman difference plot. RESULTS: The median (25th-75th percentile, range) total prolactin, post-PEG6000 and post-PEG8000 prolactin concentrations were, respectively, 36 (31-46, 23-83) µg/L, 27 (20-38, 18-72) µg/L and 24 (18-35, 16-64) µg/L for male serum samples (n=5); and 56 (39-83, 24-596) µg/L, 45 (31-67, 8-503) µg/L and 41 (28-62, 6-457) µg/L for female serum samples (n=35) (mIU/L conversion factor: 21.2). The Passing-Bablok analysis demonstrated a significant constant bias of -1.27 and a non-significant proportional bias of 0.96. The Bland-Altman plot showed a bias of -8.2% (95% limits of agreement -19.3-2.9%). CONCLUSIONS: There is a significant constant bias between the two macroprolactin precipitation methods. We changed our PEG precipitation to a PEG6000 method. Laboratories that use PEG8000 should consider the transference of the reference interval established with PEG6000 carefully.

Assessment of a four hour delay for urine samples stored without preservatives at room temperature for urinalysis.

OBJECTIVES: To determine whether urine storage at room temperature for up to 2h versus 4h changes urinalysis results. DESIGN AND METHODS: We compared the rejection rate at eight different hospital laboratories and concordance of urinalysis results (n=83; two laboratories) between urines analyzed within 2h and 4h after collection. RESULTS: The rejection rate at the two hour cutoff was significantly higher as compared to the four hour cutoff. The concordance between urinalysis results was 97-100% between the two and four hour analyses. CONCLUSION: Urine may be stored for up to 4h at room temperature without significant changes to the urinalysis results.