Estimating the intra- and inter-individual imprecision of manual pipetting.

BACKGROUND: Despite the importance of manual pipetting of fluids such as water, solutions, buffers, reagents, or biological samples in daily laboratory practice, the intra- and inter-individual imprecision of this activity has not been recently described in scientific publications. METHODS: Twenty laboratory operators were randomly enrolled for this study. Imprecision of manual pipetting was estimated by asking each laboratory professional to dispense 1 mL, 100 µL or 10 µL of distilled water for 10 consecutive times with three certified pipettes into a 50-mL plastic container placed into a gravimetric balance. The weight of the water dispensed was systematically recorded for each of the 10 repeated attempts, and the inter- and intra-operator imprecision was finally calculated and expressed as coefficient of variation (CV%). RESULTS: The mean intra-individual imprecision was 5.7% (range, 0%-11.8%) for pipetting 10 µL, 0.8% (range, 0.4%-1.9%) for pipetting 100 µL, and 0.2% (range, 0.1%-0.5%) for pipetting 1 mL. Overall, the mean inter-individual imprecision was 8.1% for pipetting 10 µL, 1.1% for pipetting 100 µL and 0.4% for pipetting 1 mL. A significantly inverse correlation was found between intra-individual pipetting imprecision and the amount of water dispensed (r = -0.80; p<0.001). No significant correlation was observed between individual pipetting performance and sex, age, qualification, and years of experience in the laboratory. CONCLUSIONS: The results of this study show that manual pipetting is plagued by a considerable intra- and inter-individual imprecision, which is inversely correlated with the amount of fluid dispensed.

Thirty-minutes' exposure to smartphone call triggers neutrophil activation in vitro.

BACKGROUND: Despite accumulating evidence about the negative health effects of exposure to electromagnetic fields emitted by mobile phones, no information is available on the potential impact of radiofrequency (RF) waves on polymorphonuclear leukocytes biology. METHODS: Two sequential whole blood tubes were collected from 16 ostensibly healthy volunteers. After placing the former tube of each subject in a plastic rack, 1 cm from a commercial smartphone (carrier frequency, 900 MHz), a call was placed on the smartphone and a communication lasting 30 min was manually activated. The latter blood tube of each volunteer was placed in another plastic rack, for an identical period of time, avoiding close contact with sources of RF waves. A complete blood count was then assessed in all whole blood samples, using Advia 2120. RESULTS: The 30-min exposure of blood to RF waves did not induce significant variations of total and differential leukocyte counts. A significant decrease was however observed for many neutrophils parameters, with median percentage variation of -3.9% for the lobularity index (LI), -29.8% for the myeloperoxidase index (MPXI), -0.6% for the neutrophil cluster mean x (NEUTx) and -0.7% for the neutrophil cluster mean y (NEUTy), respectively. The percentage of blood samples with reduced values after exposure to RF waves was 81% for LI, 88% for NEUTx and 100% for both MPXI and NEUTy. CONCLUSIONS: The results of this study show that exposure to smartphone RF waves triggers activation of neutrophils in vitro, as mirrored by the significant variations observed in many activation parameters in Advia 2120.

Albinism, stigma, subjectivity and global-local discourses in Tanzania.

Societal ideas and explanations of albinism at the local level in Tanzania are conceived in terms of family history, social relations, economic status, moral-religious positions, global-local flows of information and humanitarian actions on behalf of people with the congenital condition. This paper aims to show how the subjectivities of people with albinism in Tanzania are shaped and re-shaped through local moral conceptions as well as globalizing (bio)medical explanations of albinism. An exemplary case study of a 28-year-old woman, plus episodes from the lives of seven other informants with the condition, are analyzed in order to understand, on the one hand, local social relationships between people with albinism and other individuals in family and community settings, and on the other hand, the interconnections between persons with albinism and global humanitarian actors and the broadcast media. When stigma and marginalizing behaviors are perceived by individuals with albinism in Tanzania as impeding their social lives, they employ different coping strategies and discourses to enhance social acceptance.

Theories and practices of disability from the Global South: a critical anthropological perspective.

"Critical disability studies" (CDS) is an interdisciplinary field of research that examines social, political, economic, racial, gendered and historical constructions of bodily non-normativity across different geopolitical areas and scales. Despite its diverse and multiple contributions and objectives, current research in critical disability studies has been described as mainly focusing on disability issues in the Global North and as having universalizing tendencies. In this context, intersubjective perspectives and empirical data offered by ethnographic works in medical and disability anthropology and related disciplines have been either in accord or tension with the broader field of CDS. On the one hand, this review article illustrates the many ways anthropologists have adopted various research perspectives to explore bodily non-normativity outside settings in the Global North. On the other, it shows the importance of research by anthropologists working on topics related to disability, as well as their recent fruitful collaborations with CDS scholars and approaches. By exploring these epistemological and empirical entanglements, this paper concludes that deeper engagements between CDS and anthropology, as well as a more thorough focus on the ethnographic analysis of bodily non-normativity, can open new creative routes for the analysis of disability in various world contexts.

The order of draw: myth or science?

BACKGROUND: The potential for cross-contamination of additives among evacuated blood tubes has led to the development of the order of draw. This practice, however, is mainly based on scarce, anecdotal, and mostly outdated literature data. Therefore, the goal of this investigation was to definitely establish whether or not the indication of a specific order of draw is still justified. METHODS: The study population consisted of 57 outpatients referred to the outpatient oral anticoagulant (OA) clinic of the Academic Hospital of Verona and 58 healthy volunteers enrolled from the laboratory personnel. In OA outpatients, one serum tube was collected immediately after needle insertion, followed by a buffered sodium citrate tube and another serum tube. In the healthy volunteers, one serum tube was collected immediately after needle insertion, followed by a potassium-ethylenediaminetetraacetic acid (K2-EDTA) tube and another serum tube. After separation, the serum was tested for potassium, sodium, calcium, magnesium, and phosphorus in the first and second serum tubes. RESULTS: No significant difference could be observed between the first and the second serum tubes for any of the parameters. The bias calculated with Bland-Altman plots did not achieve statistical significance when the serum tube was collected after either a K2-EDTA or a sodium citrate tube. CONCLUSIONS: According to our data, revision of national and supranational recommendations on blood collection by venipuncture should consider that the order of draw exerts a negligible effect on sample quality, and this aspect should no longer be considered a quality criterion when evaluating the performance of phlebotomists.

Elevated urinary levels of urokinase-type plasminogen activator receptor (uPAR) in pancreatic ductal adenocarcinoma identify a clinically high-risk group.

BACKGROUND: The urokinase plasminogen activator receptor is highly expressed and its gene is amplified in about 50% of pancreatic ductal adenocarcinomas; this last feature is associated with worse prognosis. It is unknown whether the level of its soluble form (suPAR) in urine may be a diagnostic-prognostic marker in these patients. METHODS: The urinary level of suPAR was measured in 146 patients, 94 pancreatic ductal adenocarcinoma and 52 chronic pancreatitis. Urine from 104 healthy subjects with similar age and gender distribution served as controls. suPAR levels were normalized with creatinine levels (suPAR/creatinine, ng/mg) to remove urine dilution effect. RESULTS: Urinary suPAR/creatinine values of pancreatic ductal adenocarcinoma patients were significantly higher (median 9.8; 25th-75th percentiles 5.3-20.7) than those of either healthy donors (median 0; 0-0.5) or chronic pancreatitis patients (median 2.7; 0.9-4.7). The distribution of values among cancer patients was widespread and asymmetric, 53% subjects having values beyond the 95th percentile of healthy donors. The values of suPAR/creatinine did not correlate with tumour stage, Ca19-9 or CEA levels. Higher values correlated with poor prognosis among non-resected patients at univariate analysis; multivariate Cox regression identified high urinary suPAR/creatinine as an independent predictor of poor survival among all cancer patients (odds ratio 2.10, p = 0.0023), together with tumour stage (stage III odds ratio 2.65, p = 0.0017; stage IV odds ratio 4.61, p < 0.0001) and female gender (odds ratio 1.85, p = 0.01). CONCLUSIONS: A high urinary suPAR/creatinine ratio represents a useful marker for the identification of a subset of patients with poorer outcome.

The homeostasis model assessment of the insulin resistance score is not predictive of a sustained virological response in chronic hepatitis C patients.

OBJECTIVES: To investigate the independent association between the homeostasis model assessment of the insulin resistance (HOMA-IR) score and rapid virological response (RVR) and sustained virological response (SVR) in chronic hepatitis C (CHC). METHODS: Observational prospective cohort study of 412 CHC patients [59% males; mean age 45 years; genotype 1 (44%), 2 (32%), 3 (19%) and 4 (5%)] treated with pegylated interferon α plus ribavirin. RESULTS: A HOMA-IR ≥2.0 was present in 49% and a metabolic syndrome in 4% of patients. By multivariate analysis, independent predictors of SVR were the lack of advanced fibrosis (≥F3) in genotype 1 and a lower body mass index in genotype 3 patients. In the subgroup of patients in whom HCV-RNA was evaluated at week 4 (n = 281), independent predictors of RVR were HCV-RNA <700,000 IU/ml, age <40 years and lower aspartate aminotransferase:alanine aminotransferase ratio in genotype 1 and baseline HOMA-IR ≤2 in genotype 3 patients. No predictive factor of RVR was identified among genotype 2 patients. RVR was the strongest predictor of SVR among genotype 1 or 3 patients. CONCLUSIONS: In this series of treatment-naïve, Caucasian CHC patients at a low risk for the metabolic syndrome, HOMA-IR is not a predictor of SVR, irrespective of the HCV genotype, although it may predict RVR in genotype 3 infection.

Influence of the sample matrix on the stability of beta-CTX at room temperature for 24 and 48 hours.

The measurement of beta-C-telopeptides of type I collagen (beta-CTX) reflects the rate of bone resorption in a variety of metabolic bone disorders and it is increasingly used to assist diagnosis and follow-up of these pathologies. Since preanalytical biases in the results of this marker can decrease its clinical usefulness, specific stability studies should be developed to prevent that inconsistent results of laboratory testing might affect patient health and waste economical resources. Three blood samples were simultaneously collected without venous stasis into evacuated tubes containing no additives, K2 EDTA or lithium heparin, from 23 out-patients referred to our phlebotomy service for routine laboratory testing. After centrifugation and separation of the specimens, a first aliquot was immediately analyzed, whereas a second and third aliquot was processed after a 24- and 48-hour storage at room temperature (21 degrees C). Beta-CTX was assayed on the automated electrochemiluminescence analyzer E170. A modest and clinically irrelevant underestimation was observed in lithium heparin plasma when compared with either K2 EDTA (-7.1%; 95% C.I. -2.0 to -12.3%; p < 0.001) or serum (-7.8%; 95% C.I. -3.2 to -12.4%; p < 0.001), but not between serum and K2 EDTA (+0.8%, 95% C.I. -5.3 to +6.9%; p = 0.260). Storage at room temperature in K2 EDTA plasma introduced a modest and clinically negligible decay in immunoreactivity (-4.4% and -5.7% at 24 and 48 hours, respectively), whereas storage at room temperature in both serum (-17.6% and -28.6% at 24 and 48 hours, respectively) and lithium heparin plasma (-29.1% and -44.0% at 24 and 48 hours, respectively) was associated with a substantial decay and a larger inter-individual variability in the measurable concentration of the analyte. In conclusion, the results of our investigation demonstrate that EDTA plasma is the most suitable sample matrix for the storage of beta-CTX at room temperature after centrifugation.

Analytical validation of Gentian NGAL particle-enhanced enhanced turbidimetric immunoassay (PETIA).

OBJECTIVES: This study was designed to validate the analytical performance of the new Gentian particle-enhanced enhanced turbidimetric immunoassay (PETIA) for measuring neutrophil gelatinase-associated lipocalin (NGAL) in serum samples. DESIGN AND METHODS: Analytical validation of the Gentian NGAL assay was carried out on a Roche Cobas c501 and was based on assessment of limit of blank (LOB), limit of detection (LOD), functional sensitivity, imprecision, linearity and concordance with the BioPorto NGAL test. RESULTS: The LOB and LOD of Gentian NGAL were found to be 3.8 ng/mL and 6.3 ng/mL, respectively. An analytical coefficient of variation (CV) of 20% corresponded to a NGAL value of 10 ng/mL. The intra-assay and inter-assay imprecision (CV) was between 0.4 and 5.2% and 0.6 and 7.1% and the total imprecision (CV) was 3.7%. The linearity was optimal at NGAL concentrations between 37 and 1420 ng/mL (r=1.00; p<0.001). An excellent correlation was observed between values measured with Gentian NGAL and BioPorto NGAL in 74 routine serum samples (r=0.993). The mean percentage bias of the Gentian assay versus the Bioporto assay was +3.1% (95% CI, +1.6% to +4.5%). CONCLUSIONS: These results show that Gentian NGAL may be a viable option to other commercial immunoassays for both routine and urgent assessment of serum NGAL.

Analytical evaluation of three enzymatic assays for measuring total bile acids in plasma using a fully-automated clinical chemistry platform.

BACKGROUND: Although the clinical significance of measuring bile acids concentration in plasma or serum has been recognized for long in patients with hepatobiliary disease and/or bile acid malabsorption, the reference separation techniques are expensive and mostly unsuitable for early diagnosis and for measuring large volumes of samples. Therefore, this study was aimed to evaluate the analytical performance of three commercial enzymatic techniques for measuring total bile acids in plasma using a fully-automated clinical chemistry platform. METHODS: Three commercial enzymatic assays (from Diazyme, Randox and Sentinel) were adapted for use on a Cobas Roche c501. We performed imprecision and linearity studies, and we compared results with those obtained using a reference liquid chromatography-mass spectrometry (LC-MS) technique on an identical set of lithium-heparin plasma samples. RESULTS: Total imprecision was optimal, always equal or lower than 3%. All assays had optimal linearity between 3-138 µmol/L. The comparison studies showed good correlation with LC-MS data (Spearman's correlation coefficients always >0.92), but all plasma samples values were significantly underestimated using the commercial enzymatic assays (-44% for Diazyme, -16% for Randox and -12% for Sentinel). The agreement at the 10 and 40 µmol/L diagnostic thresholds of total bile acids in plasma ranged between 86-92%. This discrepancy was found to be mainly attributable to a heterogeneous composition in terms of bile acids content of the three assay calibrators. CONCLUSIONS: This study suggests that the analytical performance of the three commercial enzymatic assays is excellent, thus confirming that automation of this important test by means of enzymatic assessment may be feasible, practical, reliable and supposedly cheap. Nevertheless, the underestimation of values compared to the reference LC-MS also suggests that the local definition and validation of reference ranges according to the combination between the specific enzymatic assay and the different clinical chemistry platforms may be advisable.

Physical Exercise and DNA Injury: Good or Evil?

Regular, low-intensity physical activity is currently advocated for lowering the risk of developing many acute and especially chronic diseases. However, several lines of evidence attest that strenuous exercise may enhance inflammation and trigger the generation of free radical-mediated damage, thus overwhelming the undisputable benefits of regular, medium-intensity physical activity. Since reactive oxygen species are actively generated during high-intensity exercise, and these reactive compounds are known to impact DNA stability, we review here the current evidence about strenuous exercise and DNA injury. Despite the outcome of the various studies cannot be pooled due to considerable variation in design, sample population, outcome, and analytical techniques used to assess DNA damage, it seems reasonable to conclude that medium- to high-volume exercise triggers a certain amount of DNA injury, which appears to be transitory and directly proportional to exercise intensity. This damage, reasonably attributable to direct effect of free radicals on nucleic acids, is efficiently repaired in vivo within 24-72h. Therefore, physical exercise should not bear long-term consequences for athlete's health provided that an appropriate time of recovery between volumes of high-intensity exercise is set. Regular exertion, with a step-by-step increase of exercise load, also seems to be the most safe approach for eluding DNA instability.

Acute effects of 30 minutes of exposure to a smartphone call on in vitro platelet function.

BACKGROUND: Significant concerns are now regularly raised about the safety of excessive mobile phone use. This study was aimed to assess the acute effects of radiofrequency waves emitted by a commercial smartphone on platelet function. MATERIALS AND METHODS: Two sequential citrated blood samples were collected from 16 healthy volunteers recruited from laboratory staff. The first sample was placed in a plastic rack, 1 cm distant from a commercial smartphone receiving a 30-min call and emitting 900 MHz radiofrequency waves. The second sample was placed in another plastic rack, isolated from radiofrequency wave sources, for the same period. The platelet count and the mean platelet volume were then assessed in all blood samples, whereas platelet function was evaluated using the platelet function analyser-100 (PFA-100). RESULTS: A 30-min exposure of citrated blood to smartphone radiofrequency waves induced significant prolongation of collagen-epinephrine aggregation (median increase, 10%) and a considerable increase of mean platelet volume (median increase, 5%), whereas collagen-adenosine diphosphate aggregation and platelet count remained unchanged. DISCUSSION: This study demonstrates that smartphone radiofrequency waves induce significant perturbation of platelet structure and function, thus providing further support to concerns regarding excessive use of mobile phones. Caution should also be taken with regards to blood products containing platelets, which should be kept far away from mobile phones and smartphones throughout the production pipeline and storage period.

Impact of experimental hypercalcemia on routine haemostasis testing.

BACKGROUND: The blood to anticoagulant ratio is standardized according to the physiological calcium concentration in blood samples conventionally used for hemostasis testing. Specifically, one fixed volume of 0.109 mmol/L sodium citrate is added to 9 volumes of blood. Since little is known about the impact of hypercalcemia on the calcium-binding capacity of citrate, this study was planned to investigate the effect of experimental hypercalcemia on routine hemostasis testing. METHODS: Fifteen pooled citrated plasmas with matching lithium-heparin pooled plasma from patients with different values of prothrombin time (PT) were divided in three aliquots of 0.6mL each. The first paired aliquots of both citrate and lithium-heparin plasma were supplemented with 60µL of saline, the second paired aliquots with 30µL of saline and 30µL of calcium chloride and the third paired aliquots with 60µL of calcium chloride. Total and ionized calcium was measured in all aliquots of citrate and lithium-heparin plasma, whereas PT, activated partial thromboplastin time (APTT) and fibrinogen were measured in citrate plasma aliquots. RESULTS: Total calcium concentration gradually increased in both lithium-heparin and citrate plasma aliquots 2 and 3 compared to baseline aliquot 1. The concentration of ionized calcium also gradually increased in lithium-heparin plasma aliquots 2 and 3, whereas it remained immeasurable (i.e., <0.10 mmol/L) in all citrate plasma aliquots. No significant differences were observed for values of PT, APTT and fibrinogen in citrate plasma aliquots 2 and 3 compared to the baseline aliquot 1, with a mean bias was always comprised within the desirable quality specifications derived from biological variability data. CONCLUSION: Hypercalcemia, up to severe hypercalcemia does not generate significant bias in results of first-line coagulations tests, so that hypothetical consideration of adjusting citrate-blood ratio is unjustified in hypercalcemic patients.

Mobile phone radiofrequency exposure has no effect on DNA double strand breaks (DSB) in human lymphocytes.

BACKGROUND: The use of mobile phones has been associated with an increased risk of developing certain type of cancer, especially in long term users. Therefore, this study was aimed to investigate the potential genotoxic effect of mobile phone radiofrequency exposure on human peripheral blood mononuclear cells in vitro. METHODS: The study population consisted in 14 healthy volunteers. After collection of two whole blood samples, the former was placed in a plastic rack, 1 cm from the chassis of a commercial mobile phone (900 MHz carrier frequency), which was activated by a 30-min call. The second blood sample was instead maintained far from mobile phones or other RF sources. The influence of mobile phone RF on DNA integrity was assessed by analyzing γ-H2AX foci in lymphocytes using immunofluorescence staining kit on AKLIDES. RESULTS: No measure of γ-H2AX foci was significantly influenced by mobile phone RF exposure, nor mobile phone exposure was associated with significant risk of genetic damages in vitro (odds ratio comprised between 0.27 and 1.00). CONCLUSIONS: The results of this experimental study demonstrate that exposure of human lymphocytes to a conventional 900 MHz RF emitted by a commercial mobile phone for 30 min does not significantly impact DNA integrity.

Mobile phone exposure influences some erythrocytes parameters in vitro. A novel source of preanalytical variability?

BACKGROUND: The effect of radiofrequency exposure on human health and health care equipment is a matter of ongoing debate. This study was planned to investigate the influence of radiofrequency (RF) waves emitted by a commercial mobile phone on red blood cells (RBC) in vitro. METHODS: The study population consisted of 16 ostensibly healthy volunteers. Two whole blood specimens were collected from each volunteer. One sample was placed in a plastic rack, 1 cm distant from the chassis of a commercial mobile phone which was activated by a remote phone call lasting 30 min. The other blood sample was placed in another plastic rack, but was kept distant from any type of RF source. The main RBC parameters including RBC count, hematocrit (Ht), hemoglobin, mean corpuscular platelet volume (MPV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and RBC distribution width (RDW-CV) were assessed with an Advia 2120. RESULTS: The exposure of whole blood to the mobile phone call significantly increased Ht, hemoglobin, MCV and MCH, whereas the RBC count, MCHC and RDW-CV remained unchanged. A significant correlation was observed between variation of Ht and those of hemoglobin (p=0.008), MCV (p=0.009) or MCH (p=0.037), as well as between hemoglobin and MCV (p=0.048). Increased values were found in 13/16 (81%) samples for both Ht and hemoglobin, 14/16 (88%) samples for MCH and 16/16 (100%) samples for MCV. CONCLUSIONS: These results suggest that close mobile phone exposure may be an unappreciated and possibly underestimated cause of preanalytical bias in RBC testing.

Estimation of the imprecision on clinical chemistry testing due to fist clenching and maintenance during venipuncture.

OBJECTIVES: An experimental study was planned to assess the influence on routine clinical chemistry parameters of fist making prior to, and maintenance during, venipuncture. DESIGN AND METHODS: Blood was collected from 16 healthy volunteers with two separate sequential procedures, entailing standard venipuncture with hand opened throughout blood collection, or clenching the fist 6 times before venipuncture and maintaining the fist until completion of blood collection. After separation of lithium-heparin plasma at vacuum tubes with gel separator, 28 routine clinical chemistry parameters and serum indices were measured on Roche Cobas 6000 〈c501〉 module. RESULTS: Fist clenching and maintaining were associated with significant variations of 8/26 (31%) analytes tested. Specifically, aspartate aminotransferase (+2.3%), calcium (+2.2%), chloride (+1.0%), creatine kinase (+2.0%), magnesium (+2.3%), potassium (+13.4%), and sodium (+0.7%) increased, whereas phosphate (-5.0%) decreased. All variations except aspartate aminotransferase and creatine kinase exceeded the quality specifications for desirable imprecision. A remarkable increase of free hemoglobin in plasma (i.e., +28.2%) was also observed. The ratio of plasma potassium was significantly associated with that of plasma CK (r=0.55; p=0.029), but not with variations of other analytes. No significant correlation was observed between the ratio of free hemoglobin and those of other analytes. CONCLUSIONS: The results of our investigation demonstrate that repeated clenching and maintenance of fist during venipuncture may trigger acute variations of several routine clinical chemistry parameters, which may be attributable to muscle contraction, hemolysis or both. Accordingly, venipuncture should be performed avoiding fist clenching and maintenance.

High-density lipoprotein cholesterol values independently and inversely predict cardiac troponin T and I concentration.

BACKGROUND: This retrospective study was planned to establish potential associations between circulating values of cardiac troponins and those of conventional blood lipids. METHODS: The study population consisted of patients attending an inpatient clinic of the University Hospital of Verona during the year 2015 as part of routine cardiovascular risk assessment. No exclusion criteria were applied. Serum lipids including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) were measured using reference enzymatic techniques, whereas troponin T (TnT) was measured using a high-sensitivity (HS) immunoassay. A second analysis was also performed in the General Hospital of Verona, extracting data from the local laboratory database of all patients in whom troponin I (TnI) and blood lipids were simultaneously measured during the same year. RESULTS: In univariate analysis, HS-TnT was found to be associated with age, sex, TC, LDL-C, HDL-C, but not with TG. In multivariate linear regression analysis, age (positive correlation; P<0.001) and HDL-C (negative correlation; P=0.032) remained significantly associated with HS-TnT. The frequency of HS-TnT values >50 ng/L was higher in subjects with HDL-C <1 mmol/L than in those with HDL-C ≥1 mmol/L [odds ratio (OR), 1.84; 95% confidence interval (CI), 1.03-3.32]. The frequency of HS-TnT values >50 ng/L was also higher in elderly subjects than in younger ones (OR, 2.10; 95% CI, 1.15-3.84). The combination of age and HDL-C explained 35% of overall variability of TnT concentration. In the second analysis, HDL-C was also found to be an independent and negative predictor of TnI in multivariate linear regression analysis (P=0.010). The combination of age and HDL-C explained approximately 28% of the overall variability of TnI concentration. CONCLUSIONS: Our study suggests that HDL-C values inversely predict cardiac troponins concentration irrespective of age, sex and other blood lipids.

Postural change during venous blood collection is a major source of bias in clinical chemistry testing.

BACKGROUND: To investigate the influence of different phlebotomy postures on clinical chemistry testing. MATERIALS AND METHODS: Nineteen volunteers were recruited from the laboratory staff. A first set of samples was drawn after 25 min of resting in supine position, a second after 20 min in sitting position, and a third after 20 min in upright position. Clinical chemistry testing was performed on Roche Cobas C501. RESULTS: The plasma volume change (PVC) was -3.4% from supine to sitting, -14.1% from supine to standing and -9.7% from sitting to standing. Compared to quality specifications for bias, hemoglobin, hematocrit, albumin and total proteins exhibited meaningful increases from supine to sitting, whereas meaningful increases were observed for hemoglobin, hematocrit, albumin, alkaline phosphatase (ALP), amylase, aspartate aminotransferase (AST), total bilirubin, calcium, total and high-density lipoprotein (HDL) cholesterol, gamma-glutamyl transferase (GGT), glucose, lactate dehydrogenase (LDH), magnesium, total protein and triglycerides from sitting to standing. The parameters with meaningful bias from sitting to upright were hemoglobin, hematocrit, albumin, ALP, total bilirubin, calcium, total and HDL cholesterol, glucose, LDH and total protein. CONCLUSIONS: These results provide further support to the need of standardizing patient's posture during phlebotomy.