Impact of blood collection devices and mode of transportation on peripheral venous blood gas parameters.

BACKGROUND: Peripheral venous blood (PVB) gas analysis has become an alternative to arterial blood gas (BG) analysis in assessing acid-base balance. This study aimed to compare the effects of blood collection devices and modes of transportation on peripheral venous BG parameters. METHODS: PVB-paired specimens were collected from 40 healthy volunteers into blood gas syringes (BGS) and blood collection tubes (BCT), transported by either a pneumatic tube system (PTS) or human courier (HC) to the clinical laboratory, and compared using a two-way ANOVA or Wilcoxon signed-rank test. To determine clinical significance, the PTS and HC-transported BGS and BCT biases were compared to the total allowable error (TEA). RESULTS: PVB partial pressure of oxygen (pO2), fractional oxyhemoglobin (FO2Hb), fractional deoxyhemoglobin (FHHb), and oxygen saturation (sO2) showed statistically significant differences between BGS and BCT (p < 0.0001). Compared to HC-transported BGS and BCT, statistically significant increases in pO2, FO2Hb, sO2, oxygen content (only in BCT) (all p < 0.0001), and base excess extracellular (only in BCT; p < 0.0014) concentrations and a statistically significant decrease in FHHb concentration (p < 0.0001) were found in BGS and BCT delivered by PTS. The biases between PTS- and HC-transported BGS and BCT exceeded the TEA for many BG parameters. CONCLUSIONS: Collecting PVB in BCT is unsuitable for pO2, sO2, FO2Hb, FHHb, and oxygen content determinations.

Mass spectrometry quantitation of immunosuppressive drugs in clinical specimens using online solid-phase extraction and accurate-mass full scan-single ion monitoring.

Introduction: Therapeutic drug monitoring (TDM) of immunosuppressants is essential for optimal care of transplant patients. Immunoassays and liquid chromatography-mass spectrometry (LC-MS) are the most commonly used methods for TDM. However, immunoassays can suffer from interference from heterophile antibodies and structurally similar drugs and metabolites. Additionally, nominal-mass LC-MS assays can be difficult to optimize and are limited in the number of detectable compounds. Objectives: The aim of this study was to implement a mass spectrometry-based test for immunosuppressant TDM using online solid-phase extraction (SPE) and accurate-mass full scan-single ion monitoring (FS-SIM) data acquisition mode. Methods: LC-MS analysis was performed on a TLX-2 multi-channel HPLC with a Q-Exactive Plus mass spectrometer. TurboFlow online SPE was used for sample clean up. The accurate-mass MS was set to positive electrospray ionization mode with FS-SIM for quantitation of tacrolimus, sirolimus, everolimus, and cyclosporine A. MS2 fragmentation pattern was used for compound confirmation. Results: The method was validated in terms of precision, analytical bias, limit of quantitation, linearity, carryover, sample stability, and interference. Quantitation of tacrolimus, sirolimus, everolimus, and cyclosporine A correlated well with results from an independent reference laboratory (r = 0.926-0.984). Conclusions: Accurate-mass FS-SIM can be successfully utilized for immunosuppressant TDM with good correlation with results generated by standard methods. TurboFlow online SPE allows for a simple "protein crash and shoot" sample preparation protocol. Compared to traditional MRM, analyte quantitation by FS-SIM facilitates a streamlined assay optimization process.

Impact of recentrifugation of blood collection tubes on chemistry and immunochemistry analytes after 24 and 72 hours of refrigerated storage on the Roche Cobas 8000 platform.

BACKGROUND: We discovered that blood collection tubes (BCTs) were inadvertently recentrifuged due to improper placement on our automated preanalytical system. This study was undertaken to determine the impact of recentrifugation of blood specimens collected in serum separator (SSTs) and plasma separator (PSTs) tubes after refrigerated storage for 24 and 72 h on the concentrations of chemistry and immunochemistry analytes. METHODS: Blood was collected from 20 volunteers in SSTs and PSTs, centrifuged, and 36 chemistry and 14 immunochemistry analytes were measured at baseline in single-centrifuged tubes on a Roche Cobas 8000 chemistry platform. After baseline testing, the BCTs were refrigerated for 24 or 72 h, recentrifuged and retested. The results were compared to the single-centrifuged tubes for statistical significance. RESULTS: Recentrifugation of BCTs after 24 or 72 h of refrigerated storage showed statistically significant increases in lactate dehydrogenase activity and potassium concentration and statistically significant decreases in glucose (except in SSTs after 24 h of refrigerated storage) and CO2 concentration, but no significant differences in immunochemistry analyte concentrations. CONCLUSION: It may be safe to report most routine chemistry and immunochemistry analyte concentrations from recentrifuged SSTs and PSTs on the Roche Cobas 8000, which may save time and costs associated with recollection and retesting.

Blood collection tubes as medical devices: The potential to affect assays and proposed verification and validation processes for the clinical laboratory.

Blood collection tubes (BCTs) are an often under-recognized variable in the preanalytical phase of clinical laboratory testing. Unfortunately, even the best-designed and manufactured BCTs may not work well in all clinical settings. Clinical laboratories, in collaboration with healthcare providers, should carefully evaluate BCTs prior to putting them into clinical use to determine their limitations and ensure that patients are not placed at risk because of inaccuracies due to poor tube performance. Selection of the best BCTs can be achieved through comparing advertising materials, reviewing the literature, observing the device at a scientific meeting, receiving a demonstration, evaluating the device under simulated conditions, or testing the device with patient samples. Although many publications have discussed method validations, few detail how to perform experiments for tube verification and validation. This article highlights the most common and impactful variables related to BCTs and discusses the validation studies that a typical clinical laboratory should perform when selecting BCTs. We also present a brief review of how in vitro diagnostic devices, particularly BCTs, are regulated in the United States, the European Union, and Canada. The verification and validation of BCTs will help to avoid the economic and human costs associated with incorrect test results, including poor patient care, unnecessary testing, and delays in test results. We urge laboratorians, tube manufacturers, diagnostic companies, and other researchers to take all the necessary steps to protect against the adverse effects of BCT components and their additives on clinical assays.

Performance of chemically modified plastic blood collection tubes.

OBJECTIVE: The objective of this study was to compare newly-modified and aged chemoPET tubes, which contain no problematic surfactants, with commercially available serum blood collection tubes (BCTs) for use in analysis of cortisol, total triiodothyronine (TT3), total thyroxine (TT4), and routine clinical chemistry analytes in serum from apparently healthy volunteers and pooled quality control (QC) specimens. MATERIALS AND METHODS: Blood specimens collected from 60 apparently healthy volunteers (18 males, 42 females) and pooled QC specimens poured into seven different BCTs were analyzed by a trained phlebotomist. Cortisol, TT3, and TT4 levels were measured on an Immulite 1000 instrument and routine chemistry tests were analyzed on a Siemens RxL instrument. The significance of differences between chemoPET and other BCT types compared to glass tubes were assessed by Student's paired t-test or repeated measures ANOVA or their non-parametric equivalents. The BCT-related biases (deviation from glass tubes) in analyte concentrations were compared with the current desirable allowable bias, derived from biological variation. Serum analyte concentrations in the different BCTs that exceeded their respective significant change limits were considered clinically significant. RESULTS: No statistically and/or clinically significant differences were noted in the analyte concentrations from serum specimens and pooled QC material when our newly modified and aged chemoPET tubes were compared to glass and other BCTs. CONCLUSIONS: The chemoPET tubes described here may be a suitable alternative to serum BCTs that contain problematic surfactants known to interfere with some clinical assays on the Immulite 1000 and RxL instruments.

Transforming plastic surfaces with electrophilic backbones from hydrophobic to hydrophilic.

We demonstrate a simple nonaqueous reaction scheme for transforming the surface of plastics from hydrophobic to hydrophilic. The chemical modification is achieved by base-catalyzed trans-esterification with polyols. It is permanent, does not release contaminants, and causes no optical or mechanical distortion of the plastic. We present contact angle measurements to show successful modification of several types of plastics including poly(ethylene terephthalate) (PET) and polycarbonate (PC). Its applicability to blood analysis is explored using chemically modified PET blood collection tubes and found to be quite satisfactory. We expect this approach will reduce the cost of manufacturing plastic devices with optimized wettability and can be generalized to other types of plastic materials having an electrophilic linkage as its backbone.

Maternal proteinuria in twin compared with singleton pregnancies.

OBJECTIVE: To compare 24-hour urinary protein excretion in twin and singleton pregnancies not complicated by hypertension. METHODS: We prospectively evaluated mean 24-hour urinary protein excretion in twin and singleton pregnancies between 24 0/7 weeks and 36 0/7 weeks of gestation. Women with urinary tract infections, chronic hypertension, pregestational diabetes, and renal or autoimmune diseases were excluded. Collection adequacy was assessed by urinary creatinine excretion adjusted for maternal weight. RESULTS: Adequate samples were obtained from 50 twin and 49 singleton pregnancies at a mean gestational age of 30 weeks. At collection, the two groups were similar with regard to maternal age, gestational age, body mass index, and blood pressure. Mean urinary protein excretion was higher in twin compared with singleton pregnancies (269.3±124.1 mg compared with 204.3±92.5 mg, P=.004). Proteinuria (300 mg/day protein or greater) occurred in 38.0% (n=19) of twin and 8.2% (n=4) of singleton pregnancies (P<.001). After adjusting for confounding variables, the difference in mean total protein excretion remained significant (P=.004) and twins were more likely to have proteinuria compared with singleton pregnancies (adjusted odds ratio 9.1, 95% confidence interval 2.1-38.5). Nineteen participants developed a hypertensive disorder at a mean of 7.7 weeks after the urine collection (range 2.6-14.5 weeks). After excluding these women, proteinuria was present in 43% of twin and 7% of singleton pregnancies (P<.001). CONCLUSION: Mean 24-hour urinary protein excretion in twin pregnancies is greater than in singletons. These data suggest a reevaluation of the diagnostic criteria for preeclampsia in twin pregnancies. LEVEL OF EVIDENCE: II.

Interferences from blood collection tube components on clinical chemistry assays.

Improper design or use of blood collection devices can adversely affect the accuracy of laboratory test results. Vascular access devices, such as catheters and needles, exert shear forces during blood flow, which creates a predisposition to cell lysis. Components from blood collection tubes, such as stoppers, lubricants, surfactants, and separator gels, can leach into specimens and/or adsorb analytes from a specimen; special tube additives may also alter analyte stability. Because of these interactions with blood specimens, blood collection devices are a potential source of pre-analytical error in laboratory testing. Accurate laboratory testing requires an understanding of the complex interactions between collection devices and blood specimens. Manufacturers, vendors, and clinical laboratorians must consider the pre-analytical challenges in laboratory testing. Although other authors have described the effects of endogenous substances on clinical assay results, the effects/impact of blood collection tube additives and components have not been well systematically described or explained. This review aims to identify and describe blood collection tube additives and their components and the strategies used to minimize their effects on clinical chemistry assays.

Blood collection tube-related alterations in analyte concentrations in quality control material and serum specimens.

OBJECTIVES: Several previous studies have described the effects of interfering substances on clinical assay results; however, the effects of exogenous substances, particularly additives from blood collection tubes on quality control (QC) specimens and serum specimens have not been well examined. This study examines the effects of blood-collection tube additives on total triiodothyronine (TT3), and thyroxine (TT4), cortisol, and routine clinical chemistry tests in QC and serum specimens from apparently healthy volunteers. METHODS: QC and serum specimens were poured or collected into different blood collection tubes. TT3 and TT4, cortisol, and routine chemistry tests were analyzed from the different blood-collection tube types. RESULTS: The findings of this study demonstrate statistically and/or clinically significant blood collection tube-related alterations in the TT3, TT4, and cortisol concentrations of QC specimens and TT4 concentrations from serum specimens. CONCLUSIONS: These findings have important implications for clinical laboratories, demonstrating that QC specimens should ideally, like patients' specimens, be poured into blood collection tubes. This strategy would reveal any adverse effects caused by blood collection tubes, which otherwise would not likely be detected by most routine QC practices. The results of this study also show the importance of producing blood collection tubes that contain additives that are truly inert and do not adversely affect clinical laboratory testing.

Preanalytical quality improvement: in quality we trust.

Total quality in laboratory medicine should be defined as the guarantee that each activity throughout the total testing process is correctly performed, providing valuable medical decision-making and effective patient care. In the past decades, a 10-fold reduction in the analytical error rate has been achieved thanks to improvements in both reliability and standardization of analytical techniques, reagents, and instrumentation. Notable advances in information technology, quality control and quality assurance methods have also assured a valuable contribution for reducing diagnostic errors. Nevertheless, several lines of evidence still suggest that most errors in laboratory diagnostics fall outside the analytical phase, and the pre- and postanalytical steps have been found to be much more vulnerable. This collective paper, which is the logical continuum of the former already published in this journal 2 years ago, provides additional contribution to risk management in the preanalytical phase and is a synopsis of the lectures of the 2nd European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)-Becton Dickinson (BD) European Conference on Preanalytical Phase meeting entitled "Preanalytical quality improvement: in quality we trust" (Zagreb, Croatia, 1-2 March 2013). The leading topics that will be discussed include quality indicators for preanalytical phase, phlebotomy practices for collection of blood gas analysis and pediatric samples, lipemia and blood collection tube interferences, preanalytical requirements of urinalysis, molecular biology hemostasis and platelet testing, as well as indications on best practices for safe blood collection. Auditing of the preanalytical phase by ISO assessors and external quality assessment for preanalytical phase are also discussed.

Serum testosterone quantitation by liquid chromatography-tandem mass spectrometry: interference from blood collection tubes.

OBJECTIVES: During the development of a testosterone assay by LC-MS/MS, we encountered significant assay interference introduced by blood collection tubes. We examined a number of commonly used blood collection tubes for the presence of interference and its impact on testosterone quantitation. DESIGN AND METHODS: A number of commonly used blood collection tubes were examined by incubation of zero, low and high testosterone concentration samples with them over time, followed by sample preparation using liquid-liquid extraction and analysis by LC-MS/MS. Source of interference was identified by separately incubating blood collection tube coating, stopper and separator gel in clean glass tubes containing zero calibrator. RESULTS: Significant interference was found in some blood collection tubes, with the separator gel identified as the main source. The magnitude of the interference increases over time and mainly affected one of the two testosterone mass transitions used in the quantitation, making it readily detected by the discrepant results obtained by each of the two testosterone mass transitions. We were unable to eliminate the interference by adjustment of the sample preparation procedure, and by changing LC or MS parameters. Accurate quantitation of testosterone is possible when the problematic tubes are avoided, and blood collection tubes free of interference are used instead. CONCLUSIONS: Significant LC-MS/MS testosterone assay interference that originated from certain type of blood collection tubes hampered testosterone analysis. Examination of blood collection tube and any other laboratory test tubes for interference should therefore be an integral part of the development and validation of any LC-MS/MS assay used in a clinical diagnostic laboratory.

Elevated vitamin B12 levels in autoimmune lymphoproliferative syndrome attributable to elevated haptocorrin in lymphocytes.

OBJECTIVE: Identify the etiology of elevated B(12) in autoimmune lymphoproliferative syndrome (ALPS). DESIGN: Peripheral blood of ALPS patients with elevated B(12) and controls were evaluated. RESULTS: Total and holo-haptocorrin (HC) levels were 26- and 23-fold higher in ALPS patients, respectively. No abnormal B(12)-binding proteins were found. Western blot revealed HC in lymphocyte lysates only from ALPS patients. CONCLUSION: Elevated concentrations of B(12) found in ALPS patients were due to increased lymphocyte expression of HC.