Band 45, Heft 5

Anticoagulants are used to prevent clot formation both in vitro and in vivo. In the specific field of in vitro diagnostics, anticoagulants are commonly added to collection tubes either to maintain blood in the fluid state for hematological testing or to obtain suitable plasma for coagulation and clinical chemistry analyses. Unfortunately, no universal anticoagulant that could be used for evaluation of several laboratory parameters in a sample from a single test tube is available so far. Ethylenediamine tetraacetic acid (EDTA) is a polyprotic acid containing four carboxylic acid groups and two amine groups with lone-pair electrons that chelate calcium and several other metal ions. Calcium is necessary for a wide range of enzyme reactions of the coagulation cascade and its removal irreversibly prevents blood clotting within the collection tube. Historically, EDTA has been recommended as the anticoagulant of choice for hematological testing because it allows the best preservation of cellular components and morphology of blood cells. The remarkable expansion in laboratory test volume and complexity over recent decades has amplified the potential spectrum of applications for this anticoagulant, which can be used to stabilize blood for a variety of traditional and innovative tests. Specific data on the behavior of EDTA as an anticoagulant in hematology, including possible pitfalls, are presented. The use of EDTA for measuring cytokines, protein and peptides, and cardiac markers is described, with an outline of the protection of labile molecules provided by this anticoagulant. The use of EDTA in proteomics and in general clinical chemistry is also described in comparison with other anticoagulants and with serum samples. Finally, the possible uses of alternative anticoagulants instead of EDTA and the potential use of a universal anticoagulant are illustrated. Clin Chem Lab Med 2007;45:565–76.

Cervical screening by Pap smear involves a high rate of false negatives, necessitating frequent testing. Because women do not like the sampling procedure, many avoid being screened. Testing for the causative high-risk human papillomavirus (HPV) types, by PCR or other technologies, on self-collected (tampon) samples permits women to be monitored non-invasively. The high negative predictive value of HPV testing means a greater interval between tests, and thus reduces costs. HPV testing lends itself to primary screening. A kit for self-collection and return to a testing laboratory, followed by practitioner notification and follow-up if required, should result in wider participation. The higher accuracy of HPV testing should lead to improved cervical cancer prevention. Clin Chem Lab Med 2007;45:577–91.

Background : We examined the influence of apolipoprotein E (apoE) polymorphism on longitudinal changes in serum lipids by following the subjects participating in The Cardiovascular Risk in Young Finns Study over a 21-year period. Methods : Serum lipids were determined in randomly selected Finnish children and adolescents in 1980 and the subjects were re-examined in 1983, 1986 and after 21 years in 2001. ApoE polymorphism was determined in 1736 participants, and serum lipid values and apoE phenotypes were available for 1233 subjects. Results : ApoE phenotype-related differences in serum total and low-density lipoprotein (LDL)-cholesterol were maintained throughout the 21-year follow-up from childhood to adulthood, i.e., the apoE ɛ2 allele was consistently associated with lower and the ɛ4 allele with higher total and LDL-cholesterol (p<0.001 for all). In adulthood, there was also a significant apoE phenotype-related difference in high-density lipoprotein (HDL)-cholesterol (p=0.007), and the ɛ2 allele was associated with higher and the ɛ4 allele with lower apoA-I and HDL-cholesterol. In addition, apoB increased in the phenotype order E3/2<E3/3<E4 (E4/3+E4/4) (p<0.001). The LDL-lowering effect of the ɛ2 allele was greater in adulthood than in childhood, i.e., there was a significant apoE phenotype×time interaction (p=0.039) with longitudinal change in LDL-cholesterol. Conclusions : ApoE polymorphism is associated with lipid levels at different ages and affects the longitudinal change in LDL-cholesterol from childhood to adulthood. Clin Chem Lab Med 2007;45:592–8.

Background : Lipoprotein lipase has an important role in lipid metabolism. Elevated levels of very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) are associated with increased risk of coronary artery disease and low levels of high-density lipoprotein (HDL) are potentially atherogenic. The Hin dIII and S447X polymorphisms of the lipoprotein lipase ( LPL ) gene are associated with cardiovascular disease in some populations. Methods : LPL Hin dIII and S447X polymorphisms were analyzed in 343 individuals of 66–97 years of age from a cohort of a Brazilian elderly longitudinal study. Allele frequencies, genotype distribution and allele association with major morbidities and with serum lipid, urea, creatinine and albumin levels were also investigated. The whole sample was genotyped by PCR-restriction fragment length polymorphism (RFLP). Descriptive statistics, logistic regression analysis and t-test were used. Results : Allele frequencies were H + =0.652 and H – =0.348 for LPL Hin dIII and S=0.824 and X=0.176 for LPL S447X polymorphism. Both polymorphisms have frequencies similar to those in some European populations. LPL Hin dIII polymorphism showed significant association of the H + allele with myocardial infarction. The H – allele showed a tendency to associate with higher HDL levels. The LPL S447X S allele was associated with higher triglyceride levels. Conclusions : These findings may help to identify risk factors for subjects and families and clarify the physiopathological role of these polymorphisms in age-related diseases. Clin Chem Lab Med 2007;45:599–604.

Background : α-Thalassemia is a worldwide disease and considered to be a major public health problem in countries within the so-called thalassemia belt. The complex genetics of α-thalassemias requires diagnostic methods with the capacity to screen rapidly and accurately for common causative mutations. Methods : We developed and validated a reverse-hybridization assay (Alpha-Globin StripAssay) for the rapid and simultaneous detection of 21 α-globin mutations: two single gene deletions (–α 3.7 ; –α 4.2 ), five double gene deletions [-- MED ; -- SEA ; -- THAI ; -- FIL ; –(α) 20.5 ], ααα anti-3.7 gene triplication, two point mutations in the α1 gene (cd 14 G>A; Hb Adana) and 11 point mutations in the α2 gene (initiation cd T>C; cd 19 –G; IVS1 –5nt; cd 59 G>A; Hb Quong Sze; Hb Constant Spring; Hb Icaria; Hb Pakse; Hb Koya Dora; polyA-1; polyA-2). Results : Reliable genotyping of recombinant mutant clones and reference DNA samples was achieved by means of two corresponding test strips presenting parallel arrays of allele-specific oligonucleotides. The entire procedure from blood sampling to the identification of mutations required less than 6 h, and hybridization/detection was manual or automated. The diagnostic potential of this Alpha-Globin StripAssay was carefully evaluated on 272 pre-typed samples in a multicenter validation study. In 96.14% of the cases, StripAssay typing was completely concordant with the reference methods. Conclusions: The Alpha-Globin StripAssay proved to be a fast, easy-to-perform and reliable screening method to identify >90% of α-globin mutations in endemic areas worldwide. Clin Chem Lab Med 2007;45:605–10.

Background : The pathogenesis of breast cancer is multifactorial. Genetic predisposition, environmental factors, hormones and even infection agents are thought to interact in the manifestation of breast cancer. In particular, human leukocyte antigen (HLA) alleles play a pivotal role in cellular immunity and may be an important genetically determined host trait. Regardless of the importance and functions of HLA genes in the evolution of cancer, the allele-specific association of HLA molecules in cancer patients has not been well established. Recently, a few studies have concentrated on the association between HLA and breast cancer, but the results of these studies are controversial. Methods : We designed a study to evaluate the association between the genotype of HLA class II genes and breast cancer. HLA-DQA1 and -DQB1 polymorphisms were determined by PCR with sequence-specific primers (PCR-SSP) in 101 Taiwanese women patients with breast cancer and 115 matched control subjects. Results : Using PCR-SSP typing, HLA-DQA1 and - DQB1 locus comparison of allele frequencies between breast cancer patients and healthy controls showed no significant difference. Conclusions : We have established a significant lack of HLA-DQA1 and -DQB1 association with breast cancer in southern Taiwanese women. The results of this study may provide information for further clarification of the etiology of breast cancer in this region. Clin Chem Lab Med 2007;45:611–4.

Background : The cellular retinoic acid-binding protein II (CRABP-II), together with nuclear receptors such as the retinoid X receptor (RXR) and retinoic acid receptor (RAR), is involved in the transcriptional regulation of genes that control lipid metabolism via the retinoid signaling pathway and, as such, may be associated with disorders of lipid metabolism. Interestingly, the gene for CRABP-II is located on chromosome 1q21–23, which is a region that has been linked with disorders such as familial combined hyperlipidemia (FCHL), type 2 diabetes mellitus, and partial lipodystrophy, all of which are characterized by dyslipidemia. Methods : We investigated the hypothesis that the CRABP2 gene is involved in the regulation of lipid metabolism. Using the promoter –394T>C polymorphism of the CRABP2 gene, we performed association studies in three different cohorts: 299 healthy males, 182 HIV-infected patients and 151 patients with familial hypercholesterolemia (FH). All cholesterol measurements were performed in the absence of any lipid-lowering agents. ANOVA was performed on data adjusted for age, body mass index (BMI), gender, and use of protease inhibitors. Results : The frequency of the C allele was 0.03 in the three groups. Among healthy males, carriers of the C allele had 9% higher total plasma cholesterol (p=0.027) and 13% higher low-density lipoprotein cholesterol (LDL-C) concentrations (p=0.020). In HIV-infected patients, multivariate analysis of four measures over a 1-year period showed that carriers of the C allele had significantly higher LDL-C of between 10% and 31% (p=0.001) compared with non-carriers of the allele. FH patients who were carriers of the C allele had 16% higher LDL-C (p=0.038). The C allele was significantly over-represented among hypercholesterolemic patients (p=0.001). Conclusions: Our results show that the CRABP2 gene, a member of the retinoid signaling pathway, is associated with increased plasma LDL-C concentrations. Clin Chem Lab Med 2007;45:615–20.

Background : Human glutathione S-transferase omega-1 ( hGSTO1 ) has monomethylarsonate (MMA v ) reductase activity. Recent study suggests that two polymorphisms (E155 deletion and E208K) in hGSTO1 can be related to inter-individual variations in inorganic arsenic metabolism. As useful PCR-based genotyping methods for these hGSTO1 polymorphisms are not available and data on hGSTO1 polymorphism in African and Asian populations are insufficient, the aim of the present study was to develop a PCR-based genotyping method for E155del and E208K, and to investigate the allele frequencies of these two polymorphisms in Ovambo and Japanese populations. Methods : The E155del and E208K polymorphisms were detected using confronting two-pair primers analysis and PCR-restriction fragment length polymorphism, respectively. Results : Allele frequencies for the hGSTO1 polymorphisms were investigated in Ovambo (n=144) and Japanese (n=144) populations. For E155del, the mutation frequency in Ovambo and Japanese subjects was 0.000 and 0.017, respectively, similar to those for other populations. As for E208K polymorphism, no mutation allele was found in Ovambo or Japanese subjects. Conclusions : The present study developed a PCR-based hGSTO1 genotyping method that could be applied to a large number of individuals at most locations. Clin Chem Lab Med 2007;45:621–4.

Background : We present a patient with late-onset progressive polyneuropathy and a Congo-red positive staining of sural nerve biopsy, where routine immunohistochemical analysis failed to determine the type of amyloid deposited. Since precise determination of the amyloid type has crucial therapeutic implications, we employed our new biochemical micro-techniques, together with molecular biology methods, to characterize the amyloid protein deposited. Methods : We used a micro-method for extraction of amyloid proteins, amyloid typing by Western blotting, DNA sequencing, and restriction enzyme site analysis. Results : Our new micro-technique for biochemical analysis of fat aspirate demonstrated transthyretin (TTR) amyloid (ATTR) deposition in the patient's tissue. Sequence analysis of the TTR-encoding DNA identified a single mutation, causing a valine to alanine substitution (V32A). Conclusions: Although there are approximately 100 known TTR variants associated with peripheral neuropathy, in Israel only one patient with familial amyloid polyneuropathy (FAP), a patient of Ashkenazi origin with ATTR due to an F33I mutation, has been reported so far. Our study identified a second case of ATTR in the Israeli population, this time in a patient of Iranian-Jewish extraction. The study also emphasizes the importance of our new biochemical micro-techniques in elucidating the type of amyloid protein. Clin Chem Lab Med 2007;45:625–8.

Background : Experimental data indicate that destructive oxidative events reach their peak within the first 24 h after trauma in head injury (HI) and that brain damage occurring due to this impact can be the cause of death or irreversible permanent disabilities in affected patients. Methods : Venous blood samples were obtained from 50 HI patients within 24 h of trauma onset and from 30 age- and sex-matched normal controls (NC). Patients were divided into three different neurological outcome groups: those who died within 10 days of trauma (D), and those with severe neurological deficits (SD) or mild/no neurological deficits (MD) at 90 days after trauma. Early oxidative changes in erythrocytes were assessed by estimating an indicator of lipid peroxidative damage – thiobarbituric acid-reactive substances (TBARS) – and antioxidants [reduced glutathione (GSH) levels and superoxide dismutase (SOD) activity]. Results : In the D group, erythrocyte TBARS levels were significantly higher compared to the NC, SD and MD groups (p<0.001); GSH levels were significantly lower compared to the NC (p<0.001) and MD (p<0.01) groups and SOD activity was significantly higher than in the NC (p<0.01) and MD (p<0.01) groups. In the SD group, TBARS levels were significantly higher than in the NC (p<0.001) and MD (p<0.05) groups; GSH levels were significantly lower than in the NC (p<0.001) and MD (p<0.01) groups and SOD activity was higher compared to the NC and MD (p<0.01) groups. In the MD group, TBARS levels were significantly higher and GSH levels significantly lower compared to the NC group (p<0.001). However, we did not observe any significant change in SOD activity compared to the NC group. Conclusions : These findings indicate that early oxidative changes may reflect the severity of neurological insult and provide an early indication of patient outcome in traumatic HI. Clin Chem Lab Med 2007;45:629–33.

Background : Studies have suggested that soluble mesothelin-related protein (SMRP) can be used as a serum marker of malignant mesothelioma. Methods : We assessed the analytical performance of the Mesomark (Fujirebio Diagnostic) two-step ELISA on an automated analyser and performed a preliminary clinical evaluation. The precision of the assay and the in vitro effect of interfering substances on SMRP concentrations were investigated. The serum marker was analysed in 109 healthy subjects never exposed to asbestos, 26 healthy subjects exposed to asbestos, 33 patients with asbestosis, 33 with asbestos-related pleural plaques, 10 with non-malignant pleural diseases, 30 with lung cancer and 24 with histological diagnosis of pleural mesothelioma. Results : Using the International Mesothelioma Interest Group classification, there were nine stage IV, two stage III, four stage II and nine stage I patients. SMRP concentrations of 4.75, 11.0 and 14 nmol/mL showed a total imprecision of 3.5%, 3.1% and 3.8%. The detection limit was 0.035 nmol/mL; the mean SMRP concentration of 0.63 nmol/mL was associated with a coefficient of variation of 10%. There was no effect (p>0.05) of interfering substances. Serum samples from patients with established pleural mesothelioma had significantly higher (p<0.05) concentrations of SMRP than control healthy and patient groups. Conclusions : SMRP measured on automated systems could be useful for the diagnosis of mesothelioma in routine clinical practice. Clin Chem Lab Med 2007;45:634–8.

Background : Diabetes mellitus type 2 (DM2) affects 10% of women with polycystic ovary syndrome (PCOS). We evaluated the sensitivity and specificity of clinical and fasting biochemical parameters in screening for impaired glucose tolerance (IGT) and DM2. Methods : Women with PCOS [n=244, age 27.4±7.5 years, body mass index (BMI) 27.5±6.9 kg/m 2 ] and healthy women (n=57, age 26.8±5.8 years, BMI 21.3±2.1 kg/m 2 ) underwent basal blood sampling and an oral glucose tolerance test (oGTT). Results : Insulin resistance was identified in 40.2% of PCOS women. Impaired fasting glucose (5.6–6.9  mmol/L) was found in 30 subjects (12.3%), but the oGTT revealed IGT in only six of these cases and DM2 in one subject. IGT was found in 23 (9.4%) and DM2 in four (1.6%) of the women with PCOS. The conventional upper limits for total cholesterol, triglycerides, systolic and diastolic blood pressure and fasting glucose revealed low sensitivity for the identification of impaired glucose metabolism. Conclusions : No single parameter nor any combination of them showed an accuracy sufficient for screening of IGT or DM2 in PCOS patients. All PCOS patients should be screened using an oGTT to identify disturbances in glucose metabolism. Clin Chem Lab Med 2007;45:639–44.

Background : Cobalamin (Cbl) deficiency is a common clinical phenomenon, in particular among the elderly and possibly also among infants. Methylmalonic acid (MMA) is the most sensitive and specific marker of intracellular Cbl status, but its application is hindered by limited methods available for accurate and high-throughput MMA determination. Methods : We developed a non-laborious method for determination of MMA without the need for prior derivatization using HPLC combined with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Stable isotope-labeled methyl-d 3 -malonic acid (MMA-d 3 ) was added to 100 μL of plasma as an internal standard. After deproteinization by ultrafiltration, an acidified aliquot of the eluate was injected into the HPLC system and analyzed by LC-ESI-MS/MS monitoring of the carbonyl loss of MMA and MMA-d 3 . Results : Calibrations between 0.1 and 1.0 μM exhi-bited consistent linearity and reproducibility. The lower limit of detection for plasma MMA was 0.1 μM (signal-to-noise ratio ≥10). The intra- and inter-assay CVs of ten determinations of a plasma sample were 1.5% and 6.7%, respectively, at a mean concentration of 0.29 μM. Inter-assay CVs for 25 determinations of low, medium and high concentrations (0.22, 0.45 and 0.94 μM MMA) were 8.3%, 5.9% and 4.6%, respectively. The mean recovery of MMA added to plasma was 100%. Conclusions : By avoiding derivatization, we developed a new, non-laborious, simple and reliable high-throughput method for the determination of MMA that is suitable for automation. Clin Chem Lab Med 2007;45:645–50.

Background : Choline plays an important role in brain development. Choline-deficient diet (CDD) is known to produce (among other effects) a decrease in acetylcholine in rat brains. The aim of our study was to investigate how CDD administration during gestation and lactation could affect total antioxidant status (TAS) and activities of acetylcholinesterase (AChE), (Na + ,K + )- and Mg 2+ -ATPase in the brains of both male and female newborn and suckling (21-day-old) rats. Methods : Three different experiments were performed. Whole brains were obtained from: (a) newborn rats following gestational CDD (experiment I); (b) 21-day-old rats following gestational but not lactational CDD (experiment II); and (c) 21-day-old rats following gestational and lactational CDD (experiment III). Enzyme activities and TAS were measured spectrophotometrically. Results : In choline-deprived (CD) newborn rats, TAS and AChE and Na + ,K + -ATPase activities were signi-ficantly reduced by 23%, 24% and 50%, respectively, in the brains of both sexes. Gestational CDD caused only a decrease in TAS (−27%, p<0.001) in suckling rat brains in both sexes. No changes were observed for the other enzyme activities. Moreover, gestational and lactational CDD also led only to a decrease in TAS (−24%, p<0.001) in the suckling rat brains of both sexes. Mg 2+ -ATPase activities showed no changes after any of the experimental procedures. Conclusions : Our data suggest that the lower enzyme activities in newborn CD brains were restored to normal after 21 days of either normal or CDD lactation, possibly due to novel synaptogenesis, endogenous neuroregulation, and/or to other substances acquired by lactation. The increase in homocysteine concentration due to choline deficiency reported in the literature may be the cause of the low antioxidant capacity observed in offspring rat brains. Brain Na + ,K + -ATPase inhibition (induced by CDD) could result in modul-ations of neural excitability, metabolic energy production and neurotransmission. Clin Chem Lab Med 2007;45:651–6.

Background : Sertoli-Leydig cell tumours of the ovary account for only 0.2% of malignant ovarian tumours. Two-thirds of all patients become apparent due to the tumour's hormone production. Methods : A 41-year-old patient (gravida 4, para 4) presented with dyspnoea, enlarged abdominal girth and melaena. Diagnostic imaging was suspicious for an ovarian cancer. The standard tumour marker for ovarian cancer (CA 125) was elevated to 984 U/mL. Results : Surgical exploration of the abdomen revealed a mouldering tumour of both adnexes extending to the level of the navel. Frozen sections showed an undifferentiated carcinoma of unknown origin. Radical surgery was performed. The final histological report described a malignant sex-cord stroma tumour, a Sertoli-Leydig cell tumour, emanating from both ovaries. Analysis of preoperative blood serum showed elevated levels of CYFRA 21-1 (10.4 ng/mL), neuron-specific enolase (36.2 ng/mL), oestradiol (485 pg/mL) and CA-125 (984 U/mL). Adjuvant chemotherapy and regional hyperthermia were performed due to the malignant potential and incomplete resection of the tumour. Conclusions : Undifferentiated Sertoli-Leydig cell tumours show a poor clinical course. As only two-thirds of patients with this rare disease present with elevated hormone levels, new markers deserve further investigation to offer more specific, individualised tumour monitoring. Clin Chem Lab Med 2007;45:657–61.

Background : Since Nichols Institute Diagnostics (NID) ended production of their automated calcitonin immunoassay, evaluation of an alternative calcitonin assay was necessary. Methods : Calcitonin measured by the NID procedure was compared with a test from Diagnostic Products Corporation (DPC). Calcitonin was also measured by assays from DiaSorin (DS) and Scantibodies (SC). Results : In 187 samples, detection failed either by NID (39%) or DPC (96%) assay; in 35% of samples, the tests agreed for non-measurable calcitonin. The regression line DPC=0.78×NID−0.3 (r=0.998) fitted results from 236 samples with detectable calcitonin. A linear relationship, albeit with scattering at low concentrations, was observed. Importantly, stimulation by pentagastrin above basal calcitonin concentrations yielded similar results with both assays. Comparisons (DPC=0.80×DS−3.4 and DPC=0.81×SC−1.1) confirmed an aberrant calibration of the DPC test. To overcome the method bias, we propose a multiplication factor of 0.8 to convert NID to DPC results. Conclusions : Apparently due to non-specific effects, the DS and SC assays produced calcitonin results in samples from completely thyroidectomized patients, while the DPC assay correctly failed to detect calcitonin. Thus, the DPC assay on an Immulite ® 2000 analyzer may be used as a more accurate substitute for NID if the different calibration is noted. Clin Chem Lab Med 2007;45:662–6.

Background : Homogeneous assays for cholesterol in low-density lipoprotein (LDL) are currently in wide use for guideline-based diagnosis and monitoring of dyslipaemic or coronary conditions. In some sera from patients with impaired liver function, we measured implausibly low LDL concentrations using a sugar compound-based assay [LDL-cholesterol (LDL-C), Roche Diagnostics]. We investigated whether an interfering factor, possibly associated with cholestasis, is consistently responsible for this disturbance. Methods : We compared results of the LDL-C assay in samples with implausible (n=158) and plausible (n=65) LDL concentrations with those of another assay based on two selective detergents (LDLD, Beckman Coulter) and with sequential density ultracentrifugation. We measured total bilirubin, triglycerides, bile acids and lipoprotein X (Lp X) concentrations in samples with the described disturbance and examined the effect of bile salt addition to normal samples. Results : The LDL-C assay was negatively biased compared to the LDLD assay (bias –0.63 mmol/L) and sequential density ultracentrifugation (bias –0.85 mmol/L) in samples with an implausible lipoprotein profile, but showed good method agreement in all other samples. The bile acid concentration did not correlate with the LDL bias, and addition of bile acids showed no interference with the LDL-C assay. The Lp X concentration correlated with the bias between the LDL-C and LDLD assays (R=0.66, p<0.0001); there was no interference with the LDLD assay, even at high Lp X concentrations. Conclusions : We conclude that the LDL-C assay is subject to interference by Lp X and can provide grossly negatively biased results in cholestatic conditions. In such patients, LDL measurement with an assay based on a different method should be performed. Clin Chem Lab Med 2007;45:667–71.

Background : The aim of this study was to identify process indicators for the three phases of laboratory activity and their corresponding quality specifications in our setting (primary care centers, and second- and third-level hospitals that provide public healthcare services in Catalonia). Methods : Every 2 months, working group members met to present data obtained for quality indicators for the current processes in their laboratories. The results collected were for indicators recorded monthly from 2005 and for indicators recorded less frequently from 2004. The medians of the results obtained in all laboratories were calculated and the values obtained were established as the current specifications for the corresponding indicators. Results : The laboratories participating in this working group use 12 indicators for the key processes (three for preanalytical steps, four for analytical steps and five for postanalytical steps). The preanalytical indicators are erroneous request, erroneous sample, and samples not taken, with specifications of 4.1%, 5.0% and 1.7%, respectively. A new indicator for the analytical step is the percentage of external controls exceeding the specification (0.8%); specifications for the other three well-recognized indicators (imprecision, bias and total error) are not the subject of this study. For the postanalytical phase, the indicators (and specifications) include duplicate hard copies of reports sent to centers or clinical units (1.6%), failure in critical value reporting (0.5%), reports exceeding delivery time (0.7%), reports from referred tests that exceed delivery time (8.9%), and incidents related to the data processing network between centers (25 events per year). Conclusions : The process indicators reflect the state-of-the-art of the laboratories comprising our working group. Current performance for the analytical phase is satisfactory because it is entirely in the hands of the laboratory, while the main problems in extra-analytical phases reside in activities performed outside the laboratory (sample collection and transport, as well as non-electronic report delivery). Clin Chem Lab Med 2007;45:672–7.

Background : The aim of the present study was to investigate the analytical and diagnostic utility of B-type natriuretic peptide (BNP) and the N-terminus of this prohormone, N-terminal pro-BNP (NT-pro-BNP) testing in the emergency department to identify acute congestive heart failure (CHF). Methods : A blood sample taken from patients presenting to the emergency department with acute dyspnoea (n=80) was analyzed for natriuretic peptides using three different assays [Triage BNP (Biosite), Centaur BNP (Bayer) and Elecsys NT-pro-BNP (Roche)]. A cardiologist and a pulmonologist, blinded to the actual natriuretic peptide levels, reviewed all test results (including echocardiography, etc.) retrospectively and made a diagnosis of dyspnoea due to CHF or not. Results : Analytical testing showed good correlation and coefficients of variation of less than 10% for all three assays. Cardiac-related dyspnoea was found in 40 patients (50%). NT-proBNP and BNP values were significantly elevated in these patients. For identifying patients with CHF, BNP and NT-proBNP scored equally well (area under the receiver operating characteristic curve of 0.78, 0.77 and 0.78 for the Biosite, Roche and Bayer assays, respectively). Conclusions : In general, the different assays tested for BNP and NT-pro-BNP correlate very well in patients with suspected CHF and may aid in the risk stratification process in emergency departments. However, the value must always be interpreted in conjunction with other clinical information. It should also be considered that renal impairment can affect the results. Clin Chem Lab Med 2007;45:678–84.

Background : The aim of our study was to identify the role of External Quality Assessment (EQA) programs in improving the quality of serum creatinine measurement and glomerular filtration rate (GFR) estimation. Comparison of results achieved during EQA with National Kidney Disease Education Program and College of American Pathologists guidelines identified an urgent need for an improvement in measurement quality. We compared actual results for serum creatinine measurement within the Czech Republic EQA with the requirements of EC Directive 98/79. Methods : We used the results for 2005–2006 EQA programs. There were seven surveys involved with two samples each, and a 2006 questionnaire on the post-analytical phase survey. Results : Bias depended strongly on the creatinine concentration. However, this dependence varied for different in vitro diagnostic manufacturers, although they should all follow the same directive. We chose biological variation as the significance rate for bias and a resulting overall error of 6.9%. The proportion of results with total error <6.9% ranged from 11% to 80%. The total error for a reference sample of 94.8 μmol/L also showed significant dependence on the working calibrator used and ranged from 1% to 17%. Conclusions : The main role of EQA programs in improving the quality of creatinine measurement results and GFR calculation should be in monitoring the quality of IVD products, enabling users to adapt their use of these products accordingly. EQA programs can also educate on performing GFR estimation in a unified way. Highly commutable control materials with certified creatinine values or, alternatively, lyophilized materials with sufficient commutability proved by comparison with native frozen human sera, should become an important EQA tool. Clin Chem Lab Med 2007;45:685–8.