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.

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).

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.

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.

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.

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.

Increased expression of urokinase plasminogen activator in Quebec platelet disorder is linked to megakaryocyte differentiation.

Quebec platelet disorder (QPD) is an inherited bleeding disorder associated with increased urokinase plasminogen activator (uPA) in platelets but not in plasma, intraplatelet plasmin generation, and alpha-granule protein degradation. These abnormalities led us to investigate uPA expression by QPD CD34(+) progenitors, cultured megakaryocytes, and platelets, and whether uPA was stored in QPD alpha-granules. Although QPD CD34(+) progenitors expressed normal amounts of uPA, their differentiation into megakaryocytes abnormally increased expression of the uPA gene but not the flanking genes for vinculin or calcium/calmodulin-dependent protein kinase IIgamma on chromosome 10.

Quebec platelet disorder is linked to the urokinase plasminogen activator gene (PLAU) and increases expression of the linked allele in megakaryocytes.

Quebec platelet disorder (QPD) is an autosomal dominant disorder with high penetrance that is associated with increased risks for bleeding. The hallmark of QPD is a gain-of-function defect in fibrinolysis due to increased platelet content of urokinase plasminogen activator (uPA) without systemic fibrinolysis. We hypothesized that increased expression of uPA by differentiating QPD megakaryocytes is linked to PLAU.

Quebec platelet disorder: features, pathogenesis and treatment.

Quebec platelet disorder (QPD) is a rare, autosomal-dominant, inherited bleeding disorder that is associated with unique abnormalities in fibrinolysis. Its hallmark features are delayed-onset bleeding following hemostatic challenges that responds to fibrinolytic inhibitor therapy and increased expression and storage of the fibrinolytic enzyme urokinase plasminogen activator in platelets, without increased plasma urokinase plasminogen activator or systemic fibrinolysis. The increased urokinase plasminogen activator in QPD platelets is only partially inhibited, and, as a result, there is intraplatelet generation of plasmin, and secondary degradation of many platelet alpha-granule proteins.