Sample management for clinical biochemistry assays: Are serum and plasma interchangeable specimens?

The constrained economic context leads laboratories to centralize their routine analyses on high-throughput platforms, to which blood collection tubes are sent from peripheral sampling sites that are sometimes distantly located. Providing biochemistry results as quickly as possible implies to consolidate the maximum number of tests on a minimum number of blood collection tubes, mainly serum tubes and/or tubes with anticoagulants. However, depending on the parameters and their pre-analytical conditions, the type of matrix - serum or plasma - may have a significant impact on results, which is often unknown or underestimated in clinical practice. Importantly, the matrix-related effects may be a limit to the consolidation of analyses on a single tube, and thus must be known by laboratory professionals. The purpose of the present critical review is to put forward the main differences between using serum and plasma samples on clinical biochemistry analyses, in order to sensitize laboratory managers to the need for standardization. To enrich the debate, we also provide an additional comparison of serum and plasma concentrations for approximately 30 biochemistry parameters. Properties, advantages, and disadvantages of serum and plasma are discussed from a pre-analytical standpoint - before, during, and after centrifugation - with an emphasis on the importance of temperature, delay, and transport conditions. Then, differences in results between these matrices are addressed for many classes of biochemistry markers, particularly proteins, enzymes, electrolytes, lipids, circulating nucleic acids, metabolomics markers, and therapeutic drugs. Finally, important key-points are proposed to help others choose the best sample matrix and guarantee quality of clinical biochemistry assays. Moreover, awareness of the implications of using serum and plasma samples on various parameters assayed in the laboratory is an important requirement to ensure reliable results and improve patient care.

Blood transfusions may impair endothelium-dependent vasodilatation during coronary artery bypass surgery.

OBJECTIVE: The hemolytic product free-hemoglobin (fHb) reduces nitric oxide (NO) bioavailability. The present study aims to establish whether administration of different blood transfusions result in increased circulating fHb levels and NO consumption with effects on arterial NO-dependent blood flow in patients undergoing CABG surgery. METHODS: Ninety-five consecutive patients undergoing elective CABG surgery were prospectively divided in four groups based on blood transfusion requirements during surgery: stored blood cells (SBC, n. 21), intraoperative autologous salvaged blood (ASB, n. 25), SBC and ASB (n.22), no transfusion (control, n. 27). Blood samples were collected before and after intervention to analyse plasma levels of fHb and NO consumption. Endothelium-dependent relaxation was assessed in left internal mammary artery (LIMA) rings harvested before chest closure. Peripheral artery tonometry was assessed after intervention. RESULTS: Transfusions with SBC increased plasma fHb (p<0.05). Transfusions of ASB resulted in higher plasma fHb compared to SBC (p<0.01). fHb concentrations directly correlated with NO consumption (r=0.65, p<0.001). Maximal endothelium-dependent relaxation in LIMA was significantly attenuated in SBC and ASB patients compared to control (15.2±3.1% vs 21.1±2.5% vs 43±5.0% respectively; p<0.01). Significant correlations were identified between the aortic pressure wave velocity, plasma fHb concentration and NO consumption (p<0.01). CONCLUSIONS: Intraoperative blood transfusions and particularly autologous salvaged blood impair endothelium-dependent relaxation through NO scavenging by fHb. These findings obtained in vitro and in vivo provide new insights into the adverse relation between blood transfusions and patient outcome.

Aberrant MicroRNA Expression in Patients With Endometrial Cancer.

OBJECTIVE: Current evidence suggests that no single serum biomarker displays satisfactory diagnostic performance in patients with endometrial carcinoma (EC), the most frequent gynecological cancer in developed countries. However, aberrant tissue microRNA (miRNA) expression has been recently described in EC. Therefore, this study aimed to investigate the differential expression of 4 serum miRNAs and their association with CA125 (cancer antigen 125) and HE4 (human epididymis protein 4) in EC patients and in a control population. METHODS: Forty-six consecutive women with EC and 28 matched control subjects without a history of cancer or other diseases were enrolled. Total serum RNA was extracted using mirVana PARIS Kit. TaqMan MicroRNA Assay was used for quantitative real-time reverse transcriptase-polymerase chain reaction on ABI 7500 Sequence Detection System to assess differential miRNAs expression. The relative expression levels of 4 miRNAs (miR-222, miR-223, miR-186, and miR-204) were normalized to miR-16 and calculated using the 2-△Ct approach. RESULTS: Serum levels of miR-186, miR-222, and miR-223 appeared to be significantly higher in patients compared with control subjects (P = 0.004, P = 0.002, and P < 0.0001). Contrarily, serum miR-204 was found to be significantly lower in EC patients (P < 0.0001). The diagnostic performance of miRNAs was found to be significantly better than that of CA125. Among the various biomarker tested, serum miR-204 and HE4 exhibited the best diagnostic performance for discriminating EC patients from control subjects. CONCLUSIONS: These results underpin that the 4 miRNAs that we have investigated are implicated in development and progression of EC, thus opening new avenues in EC diagnostics.

Pre-analytical phase management: a review of the procedures from patient preparation to laboratory analysis.

The pre-analytical phase encompasses all the procedures before the start of laboratory testing. This phase of the testing process is responsible for the majority of the laboratory errors, since the related procedures involve many sorts of non-laboratory professionals working outside the laboratory setting, thus without direct supervision by the laboratory staff. Therefore, either correct organization or management of both personnel and procedures that regard blood specimen collection by venipuncture are of fundamental importance, since the various steps for performing blood collection represent per se sources of laboratory variability. The aim of this (non-systematic) review addressed to healthcare professionals is to highlight the importance of blood specimen management (from patient preparation to laboratory analyses), as a tool to prevent laboratory errors, with the concept that laboratory results from inappropriate blood specimens are inconsistent and do not allow proper treatment nor monitoring of the patient.

The impact of fist clenching and its maintenance during venipuncture on routine hematology testing.

BACKGROUND: Prevention of a disturbance of the blood vessel allows phlebotomists to collect a blood specimen by venipuncture that will truly mirror the patient condition. This study was aimed to evaluate the impact of repeated fist clenching and maintenance of the fist during blood collection by venipuncture for routine hematology testing. METHODS: Blood were collected from 16 healthy volunteers with two separate sequential procedures, entailing standard venipuncture with hand opened throughout blood collection, or clenching the fist six times before venipuncture and maintaining the fist until completion of blood collection. The parameters tested included red blood cell (RBC) count, hemoglobin, hematocrit, mean corpuscular volume (MCV), RBC distribution width, white blood cell count and differential, including neutrophils, lymphocytes, monocytes, eosinophils, basophils, large unstained cells, platelet count, mean platelet volume, and reticulocytes. The results were reported as median and interquartile range. The comparison of data obtained with the two different venipuncture procedures (i.e., with or without fist clenching and closed hand) was performed with Wilcoxon-Mann-Whitney ranked-pairs test. The degree of statistical significance was set at P<.01. RESULTS AND CONCLUSION: Fist clenching and maintenance during blood collection for routine hematology testing was effective to increase the MCV by 1.2% (P<.001). All others hematological parameters were not significantly biased by fist clenching, though hematocrit, neutrophils, eosinophils, and reticulocytes displayed mindful of trends. We hence advise patients against clenching their fist before blood collection for hematology testing.

Plasma Leptin in Patients at Intermediate to High Cardiovascular Risk With and Without Type 2 Diabetes Mellitus.

BACKGROUND: A number of clinical studies have demonstrated that leptin concentrations are related to the metabolic disturbances that constitute the metabolic syndrome (MetS) and to diabetes mellitus (DM). AIM: To investigate possible determinants of leptin concentrations in a sample of patients at high cardiovascular (CV) risk carrying two or more features of the MetS and to investigate if any difference exist between at risk patients with or without DM. METHODS: Serum leptin concentrations were measured in 60 consecutive male patients affected by at least two CV risk factors which belong to the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) definition of MetS: 30 patients affected by type 2 DM (T2DM) and 30 nondiabetic patients (non-T2DM). Nineteen healthy subjects were included in the study as a control group (HC). RESULTS: Leptin was significantly higher in patients carrying two or more features of the MetS compared with HC (P = 0.02). Stratifying MetS patients for DM, we found that leptin level was higher in non-T2DM patients (7.8 ng/ml), intermediate in T2DM (6.2 ng/ml), and lower in HC (4.6 ng/ml). In MetS patients, a positive correlation was found between leptin and waist, triglycerides, and number of MetS criteria. After stratification for T2DM, the correlations were still significant in the non-T2DM but not in the T2DM group. CONCLUSIONS: In our sample of moderate-to-high-risk patients, leptin level is positively associated with waist circumference and triglycerides but only in non-T2DM patients. Our data suggest that diabetic subjects could modulate leptin production in a different way compared with patients carrying other MetS-related anomalies.

Birth season predicts the values of red blood cell distribution width (RDW) in adulthood.

BACKGROUND: Recent evidence suggests that red blood cell distribution width (RDW), a simple measure of anisocytosis, may predict the risk of adverse clinical outcomes in both the general population and in patients with severe pathologies. Since it was also shown that the birth season influences the lifetime disease risk, this study was aimed to investigate whether an association may exist between adult RDW values and birth season. METHODS: The study population consisted in healthy Caucasian blood donors aged 18 or older, undergoing routine laboratory testing before regular blood donation. RESULTS: Overall, 6122 healthy blood donors were included in this study (median age 41 years; 1807 women and 4315 men). Age, sex, mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) but not hemoglobin and hematocrit were found to be independent predictors of RDW. When the study population was classified according to birth season, a significant difference was found for RDW values, but not for age, sex, hemoglobin, hematocrit, MCV and MCH. Subjects born in spring exhibited RDW values generally higher compared to those born in other seasons, reaching statistical significance when compared to those born in summer and winter. In particular, subjects born in spring had a 33% (p=0.014) higher probability of displaying increased RDW values in adulthood compared to those with summer birth. CONCLUSIONS: Despite additional studies that are needed to confirm these original findings, the evidence that a significant link exists between birth season and adult anisocytosis provides a plausible explanation for the association between birth season and lifetime disease risk.

Plasma Expression Levels of Circulating miR-21 are not Useful for Diagnosing and Monitoring Colorectal Cancer.

BACKGROUND: Recent evidence suggests that microRNAs play an important role in cancer diagnostics. We assessed plasma microRNA-21 levels in patients with colorectal cancer (CRC) at different stages and in patients with benign polyps. METHODS: Plasma levels of miR-21 were assessed by quantitative reverse transcription polymerase chain reaction assay in plasma samples of 76 CRC patients and in 20 patients with benign polyps. Differences between groups were evaluated with Mann-Whitney and Kruskal-Wallis tests. RESULTS: No significant differences of miR-21 plasma levels were observed between CRC patients and subjects with benign polyps (p > 0.05). Also, no significant differences were found between CRC patients with advanced (III-IV) or early cancer stages (I-II) (p > 0.05). CONCLUSIONS: These results do not support the hypothesis that circulating miR-21 expression is increased in adenoma-carcinoma-advanced carcinoma sequence. Accordingly, plasma miR-21 assessment does not appear to be a useful biomarker for diagnosing and staging CRC.

Role of JAK2 V617F mutation and aberrant expression of microRNA-143 in myeloproliferative neoplasms.

BACKGROUND: Myeloproliferative neoplasms (MPNs) are clonal myeloid disorders characterized by the overproduction of mature blood cells. The pathogenetic hallmark of MPNs is the dysregulation of JAK-STAT signaling, usually associated with the JAK2 V617F mutation. Multiple additional genetic and epigenetic alterations that constitutively activate the JAK-STAT signaling pathway have been described, including the modulation of the microRNAs (miRs) expression levels. The aims of our study were to investigate JAK2 V617F mutation allele burden and miR-143 expression levels in MPNs patients and to investigate the correlation between these genetic signatures and hematological parameters. METHODS: In total 78 patients with a clinical diagnosis of polycythemia vera (PV), essential thrombocythemia (ET) and idiopathic myelofibrosis (IM), made according to the WHO 2008 criteria, were included in the study. Twenty healthy subjects were checked as controls. Quantification of JAK2 V617F mutation and miR-143 expression levels were determined by real-time quantitative polymerase chain reaction. RESULTS: The miR-143 expression in MPNs patients was 2.97-fold higher than in controls. JAK2 V617F mutation allele burden and miR-143 expression level resulted higher in PV and IM respect to ET patients. Patients who had V617F allele burden >50% displayed a higher miRNA-143 expression level than patients with allele burden <50%. In MPNs patients, a statistically significant positive correlation was observed between JAK2 V617F mutation allele burden and hemoglobin and hematocrit values and between miR-143 expression levels and platelet count. CONCLUSIONS: Our findings of aberrant miR-143 expression support the concept that factors other than JAK2 V617F mutation may contribute to the pathogenesis and some clinical signs of MPNs.

The baseline serum value of α-amylase is a significant predictor of distance running performance.

BACKGROUND: This study was planned to investigate whether serum α-amylase concentration may be associated with running performance, physiological characteristics and other clinical chemistry analytes in a large sample of recreational athletes undergoing distance running. METHODS: Forty-three amateur runners successfully concluded a 21.1 km half-marathon at 75%-85% of their maximal oxygen uptake (VO2max). Blood was drawn during warm up and 15 min after conclusion of the run. RESULTS: After correction for body weight change, significant post-run increases were observed for serum values of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, creatine kinase (CK), iron, lactate dehydrogenase (LDH), triglycerides, urea and uric acid, whereas the values of body weight, glomerular filtration rate, total and low density lipoprotein-cholesterol were significantly decreased. The concentration of serum α-amylase was unchanged. In univariate analysis, significant associations with running performance were found for gender, VO2max, training regimen and pre-run serum values of α-amylase, CK, glucose, high density lipoprotein-cholesterol, LDH, urea and uric acid. In multivariate analysis, only VO2max (p=0.042) and baseline α-amylase (p=0.021) remained significant predictors of running performance. The combination of these two variables predicted 71% of variance in running performance. The baseline concentration of serum α-amylase was positively correlated with variation of serum glucose during the trial (r=0.345; p=0.025) and negatively with capillary blood lactate at the end of the run (r=-0.352; p=0.021). CONCLUSIONS: We showed that the baseline serum α-amylase concentration significantly and independently predicts distance running performance in recreational runners.

Serum copeptin and midregion proadrenomedullin (MR-proADM) after an ultramarathon.

BACKGROUND: Although it is widely acknowledged that physical activity confers several health benefits, it remains uncertain whether strenuous and physically demanding exercise might determine biological effects that might turn to be ultimately unfavorable for health. Copeptin and midregion proadrenomedullin (MR-proADM) are emerging cardiovascular and stress biomarkers, but little is known about the influence of strenuous physical exercise on their concentrations. METHODS: The present study was performed to investigate the variation of copeptin and MRproADM, along with that of serum creatinine and estimated glomerular filtration rate before and after a 60 km ultramarathon in 16 healthy Caucasian males. RESULTS: The serum concentrations of both copeptin and MR-proADM remarkably increased after the 60 km run, by 6.4 times (interquartile range (IQR), 2.710.4) and 2.3 times (IQR, 1.8-2.6), respectively. A highly significant correlation was observed between the increase of creatinine and MR-proADM, but not between serum creatinine and copeptin. The percentage of subjects exhibiting values above the upper limit of the reference range in male was 0% for both copeptin and MR-proADM before the ultramarathon, but increased to respectively 81 and 63% postexercise. CONCLUSION: The evidence that an ultramarathon causes a substantial increase of copeptin and MR-proADM raises doubts as to whether exhaustive exercise might be considered globally beneficial or even safe, especially in unfit or/and untrained population.

Circulating nucleic acids and hemostasis: biological basis behind their relationship and technical issues in assessment.

Nucleic acids (NAs) constitute the backbone of cellular life permitting conservation, transmission, and execution of genetic information. In the past few years, new unexpected functions for NAs, projecting them also beyond nuclear and cellular boundaries have been recognized: circulating cell-free nucleic acids (cfNAs), histones, DNA-histone complexes, microRNAs (miRs) may have a regulatory role in physiological and pathological processes. In particular, several lines of evidence suggest that they can constitute unconventional mediators of thrombus formation, intervening both in hemostasis and thrombosis. Furthermore, in the past decade, the possibility to detect and quantify these in plasma and/or in serum has led to their ancillary use as potential markers in various medical conditions. The use of these as markers within the fields of thrombosis and hemostasis looks promising: the potential implications include the possibility to assess patients' risk profiles for thrombotic events and the identification of more directed targets for pharmacologic intervention. The major impediment is that, to date, the methods by which NAs are explored, still largely differ between published studies and standardized procedures are still lacking. Future research should focus on the physiological mechanisms underlying the activities of such mediators in specific thrombotic conditions and on the definition of reliable methods for their quantification in biological fluids.

The concentration of high-sensitivity troponin I, galectin-3 and NT-proBNP substantially increase after a 60-km ultramarathon.

BACKGROUND: The leading mechanisms responsible for the most prevalent and serious cardiac injuries include myocardiocyte stretch, myocardiocyte necrosis and cardiac fibrosis, which can now be reliably mirrored by measurement of natriuretic peptides, cardiospecific troponins and galectin-3, respectively. Although a large amount of knowledge has been gathered about the behavior and clinical significance of these biomarkers in patients with cardiac disorders, less information is available on their biology in paraphysiological conditions, including high-intensity endurance exercise. METHODS: The study population consisted of 18 trained athletes, who performed a 60-km ultramarathon run. Blood was collected before the run (i.e., "baseline") and immediately after the end of the ultramarathon ("post-marathon") for measurement of serum high-sensitivity troponin I (TnI), NT-proBNP and galectin-3. RESULTS: The concentration of all biomarkers measured in the post-marathon samples was remarkably increased as compared with the values obtained on baseline specimens. In particular, the median increase was 3.3 for TnI, 3.5 for NT-proBNP and 2.4 for galectin-3, respectively. The frequency of values exceeding the diagnostic threshold did not differ at baseline and after the ultramarathon for TnI (6% vs. 25%; p=0.15), instead was significantly increased for NT-proBNP (0% vs. 28%; p=0.016) and galectin-3 (0% vs. 67%; p<0.001). No significant correlation was found among the increase of any of the three biomarkers. CONCLUSIONS: The results of this study demonstrate that high-intensity endurance exercise is associated with biochemical abnormalities that may reflect adverse consequences on cardiac structure and biology.

Increased red blood cell distribution width (RDW) is associated with higher glycosylated hemoglobin (HbA1c) in the elderly.

BACKGROUND: The aim of the present study was to examine whether red blood cell distribution width may be associated with glycated hemoglobin (HbA1c) in a large cohort of unselected elderly Italian outpatients. METHODS: We performed a retrospective search on the database of the laboratory information system of the clinical chemistry laboratory of the General Hospital of Verona (Italy), to retrieve combined results of complete blood count (CBC) and HbA1c performed in outpatients aged 65 years or older during the year 2013. RESULTS: Cumulative results of CBC and HbA1c could be retrieved for 2515 outpatients aged 65 years or older throughout the study period. In the entire population, HbA1c was significantly associated with RDW values (r = 0.11; p < 0.001), even after adjustment for age and gender. The concentration of HbA1c was significantly higher in patients with RDW > 14.0% than in those with RDW ≤ 14.0% (45 versus 43 mmol/mol; p < 0.001). The rate of HbA1c > 53 mmol/mol was greater among patients with RDW > 14.0% than among those with RDW ≤ 14.0% (19 versus 15%; p = 0.006). The odds ratio of an increased RDW value for HbA1c > 53 mmol/mol was 1.33 (95% CI, 1.08 - 1.65; p = 0.01). CONCLUSIONS: The results of this retrospective analysis extend the previous finding that RDW is significantly associated with HbA1c to a large cohort of unselected and elderly southern European outpatients. Since RDW is a simple and inexpensive parameter, it may be regarded as a potential, innovative biomarker for improving risk assessment of developing diabetes.

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.

Lack of an association between circulating adiponectin levels and risk of colorectal adenoma.

BACKGROUND: The putative association between serum adiponectin levels and colorectal adenomas is actually under debate. The aim of this study was to investigate this association in relation to factors known to influence the levels of adiponectin such as anthropometric, metabolic, inflammatory parameters as well as lifestyle individual characteristics. METHODS: 40 patients with adenomas and 40 controls were enrolled. Body weight, height, waist circumference, and blood pressure were recorded. Fasting plasma glucose, lipids, C-reactive protein, and adiponectin levels were measured. Metabolic Syndrome was defined and lifestyle characteristics assessed. RESULTS: No differences were found in adiponectin values between patients and controls (p = 0.101). Adiponectin levels were significantly higher in females than in males (p = 0.004). Adiponectin levels did not result in significant association with colorectal adenomas even after adjustment for metabolic and life style parameters. CONCLUSIONS: This study did not confirm the hypothesis that high levels of adiponectin confer decreased risk of colorectal adenomas.

Quality impact on diagnostic blood specimen collection using a new device to relieve venipuncture pain.

A new device called Buzzy(®) has been recently presented that combines a cooling ice pack and a vibrating motor in order to relieve the venipuncture pain. The aim of this study was to evaluate the impact of Buzzy(®) use during diagnostic blood specimen collection by venipuncture for routine immunochemistry tests. Blood was collected from 100 volunteers by a single, expert phlebotomist. A vein was located on the left forearm without applying tourniquet, in order to prevent any interference from venous stasis, and blood samples were collected using a 20-G straight needle directly into 5 mL vacuum tubes with clot activator and gel separator. In sequence, external cold and vibration by Buzzy(®) was applied on the right forearm-5 cm above the chosen puncture site-for 1 min before venipuncture and continued until the end of the same procedure already done in the left forearm. The panel of tests included the following: glucose, total cholesterol, HDL-cholesterol, triglycerides, total protein, albumin, c-reactive protein, urea, creatinine, uric acid, alkaline phosphatase, amylase, AST, ALT, g-glutamyltransferase, lactate dehydrogenase, creatine kinase, total bilirubin, phosphorus, calcium, magnesium, iron, sodium, potassium, chloride, lipase, cortisol, insulin, thyroid-stimulating hormone, total triiodothyronine, free triiodothyronine, total thyroxine, free thyroxine and haemolysis index. Clinically significant differences between samples were found only for: total protein, albumin and transferrin. The Buzzy(®) can be used during diagnostic blood specimens collection by venipuncture for the majority of the routine immunochemistry tests. We only suggest avoiding this device during blood collection when protein, albumin and transferrin determinations should be performed.

The Renalase Asp37Glu polymorphism is not associated with hypertension and cardiovascular events in an urban-based prospective cohort: the Malmö Diet and cancer study.

BACKGROUND: Renalase (gene name RNLS), a recently discovered enzyme with monoamine oxidase activity, is implicated in the degradation of catecholamines. Recent studies delineate a possible role of this enzyme in blood pressure (BP) maintenance and cardiac protection and two single nucleotide polymorphisms, RNLS rs2576178 A > G and rs2296545 C > G have been associated with hypertension. The latter SNP leads to a non synonymous Asp to Glu substitution deleting a flavin adenine dinucleotide (FAD) binding site with possible impaired functionality. We tested the hypothesis that these polymorphisms could affect BP levels, hypertension prevalence, and risk of incident cardiovascular events in middle-aged Swedes. METHODS: The polymorphisms were genotyped in 5696 participants of the population-based Cardiovascular Cohort of the "Malmö Diet and Cancer" (MDC-CC). The incidence of cardiovascular events (coronary events [n = 408], strokes [n = 330], heart failure [n = 190] and atrial fibrillation/flutter [n = 406]) was monitored for an average of approximately 15 years of follow-up. RESULTS: Both before and after adjustment for sex, age and BMI the polymorphisms did not show any effect on BP level and hypertension prevalence. Before and after adjustment for major cardiovascular risk factors, the hazard ratio for cardiac and cerebrovascular events was not significantly different in carriers of different genotypes. A significant interaction was found between the rs2296545 C > G and age with respect to BP/hypertension. CONCLUSIONS: Our data do not support a major role for these RNLS polymorphisms in determining BP level and incident events at population level. The positive interaction with age suggest that the effect of the rs2296545 C > G polymorphism, if any, could vary between different ages.

Quality standards for sample collection in coagulation testing.

Preanalytical activities, especially those directly connected with blood sample collection and handling, are the most vulnerable steps throughout the testing process. The receipt of unsuitable samples is commonplace in laboratory practice and represents a serious problem, given the reliability of test results can be adversely compromised following analysis of these specimens. The basic criteria for an appropriate and safe venipuncture are nearly identical to those used for collecting blood for clinical chemistry and immunochemistry testing, and entail proper patient identification, use of the correct technique, as well as appropriate devices and needles. There are, however, some peculiar aspects, which are deemed to be particularly critical when collecting quality specimens for clot-based tests, and these require clearer recognition. These include prevention of prolonged venous stasis, collection of nonhemolyzed specimens, order of draw, and appropriate filling and mixing of the primary collection tubes. All of these important preanalytical issues are discussed in this article, and evidence-based suggestions as well as recommendations on how to obtain a high-quality sample for coagulation testing are also illustrated. We have also performed an investigation aimed to identify variation of test results due to underfilling of primary blood tubes, and have identified a clinically significant bias in test results when tubes are drawn at less than 89% of total fill for activated partial thromboplastin time, less than 78% for fibrinogen, and less than 67% for coagulation factor VIII, whereas prothrombin time and activated protein C resistance remain relatively reliable even in tubes drawn at 67% of the nominal volume.

The functional variant V433M of the CYP4F2 and the metabolic syndrome in Swedes.

BACKGROUND AND AIM: The genetic basis of Metabolic syndrome (MetS) is largely unknown but a link with salt sensitivity is recognized. The cytochrome P450 isoform 4F2 (CYP4F2) is involved in renal production of 20-hydroxyeicosatethraenoic acid (20-HETE), a natriuretic substance associated with salt sensitivity. The same enzyme is implicated in ω-hydroxylation of very long and medium chain fatty acids in the liver suggesting its possible influence on gluco-metabolic components of MetS. The aim of the present study was to evaluate the effect of CYP4F2 V433M, a functional polymorphism previously associated with hypertension via renal salt reabsorption, on the individual components of MetS and MetS itself. METHODS: The polymorphism was genotyped in the cardiovascular cohort of the Malmö Diet and Cancer (MDC-CVA) study and successively in the Malmö Preventive Project (MPP) cohort. Different definitions of the MetS were applied. RESULTS: In the MDC-CVA, male, but not female, CYP4F2 M433 carriers had significantly higher levels of waist, triglycerides, BP and a composite sum of MetS phenotypes (MetS score) beside lower HDL-cholesterol respect to V-homozygotes. MetS, as defined in the ATPIII and the AHA/NHLBI definitions, was more prevalent in M-carriers with respect to V-homozygotes. In the MPP cohort, significant association was detectable only for triglycerides at baseline and for Diastolic BP at reinvestigation in male M-carriers. CONCLUSION: The initial positive association of the CYP4F2 V433M polymorphism with components of MetS and MetS itself, found in MDC-CVA, was partially denied in another large cohort. The first association either could be due to a false positive result or alternatively, different genetic background or population stratification could have hidden the effect of the polymorphism in the replication cohort.