Band 49, Heft 5

With the introduction of new anticoagulant agents, there is a need for information on which coagulation tests are most suitable. These agents react differently to assays used to monitor older anticoagulant agents because they have alternative modes of action. Therefore, other tests, or modifications of existing tests which are more appropriate for newer agents, are needed. The prothrombin time test (with conversion to the international normalized ratio) is usually used to monitor warfarin. However, conversion to the international normalized ratio is not appropriate for measuring the effects of fondaparinux, dabigatran, rivaroxaban or apixaban. Instead, chromogenic assays, one-step prothrombinase-induced clotting time test and the HepTest with reduced incubation time, are among the different or modified tests that appear to give the most reproducible and accurate results. The tests show variations in response to anticoagulants – some of which have clinical relevance. Thus, it is important to be aware of the observed variations in order to prevent the misinterpretation of test results.

Dementia is a growing public health concern because of the lack of effective curative treatment options and a rising global prevalence. Alzheimer’s disease (AD) is the most common type of dementia, affecting 60%–70% of all patients with dementia. The main pathological features of Alzheimer’s dementia are neurofibrillary tangles and senile plaques caused by progressive deposition of β-amyloid in the brain, but its underlying pathological basis is unclear. In common late onset AD sporadic forms (95% of all AD cases), a major genetic risk factor is the apolipoproteinE-ɛ4 (ApoE-ɛ4) alleles, and other genetic determinants have also been proposed to play causative role. This review focuses on biomarkers and subsequent changes in continuous measurement of cognitive and functional abilities in patients with mild cognitive impairment (MCI) and AD that aim to achieve a higher diagnostic accuracy for AD along with clinical assessment, neuropsychological testing and neuroimaging.

Hematologic parameters are commonly utilized in sports medicine and antidoping testing. However, there are no universally accepted methodologies for comparing the performance of automated blood analyzer systems. To address this problem, we selected and examined 19 studies from a review of literature published from 2000 to 2010. Meaningful discrepancies were found between measurements obtained with different analytical systems. Because harmonization and clear standardization of methods are lacking, the analytical variability often largely exceeds intra- and inter-individual biological differences, producing equivocal test results unreliable for clinical and antidoping testing. A central criticality to applying the Bayesian approach is analytical variability, but the use of different analytical technologies precludes the comparison of inter-methods for determining the robustness of blood variables and their clinical significance. Therefore, future multicenter studies are needed to compare analytical methodologies and blood analyzer systems, and to establish worldwide-accepted standards and quality control protocols.

Autoinflammatory diseases (AID) are inherited errors of innate immunity which, although individually uncommon, collectively set up an emerging chapter of medicine. Careful analysis and identification of AID is essential to prompt effective treatment and improve survival and quality of life in these patients. Research into pediatric AID is lagging behind studies in adults, though a better understanding of AID in infancy could lead to improved diagnostic protocols and reduce long-term disability. This review provides a detailed summary of monogenic AID in childhood to help pediatricians correctly recognize these conditions and also highlight recent developments in the laboratory diagnostic work-up.

As a part of a series of yearly meeting, in May 2010 over 40 medical laboratory opinion leaders, pathologists, clinical biochemists and physicians from Europe, Israel and South Africa gathered together in Bardolino, Italy to discuss issues and current challenges for laboratory medicine, including a) the use of biological variation 10 years after the Stockholm Conference; b) achieving quality in point-of-care testing; c) assessing risk and controlling sources of error in the laboratory; d) determining the appropriate frequency of quality control; and f) putting laboratory medicine at the core of patient care. The intended goal of the convocation was to give laboratory professionals from different countries and backgrounds the opportunity to share ideas, concerns and experiences in previously mentioned areas of interest. This paper provide a synopsis of the reports from each working group.

Background: Nonenzymatic glycation appears to be an important factor in the pathogenesis of diabetic complications. Fructosamine 3-kinase ( FN3K ), initially identified in erythrocytes, appears to be responsible for the removal of fructosamine from proteins, suggesting a protective role in nonenzymatic glycation. Recently, genetic variants in the FN3K gene have been studied in diabetic patients. The aim of our study was the molecular characterization of the FN3K gene in a representative group of Italian patients with type 1 (T1DM) and 2 (T2DM) diabetes mellitus and in a cohort of healthy controls. Methods: Seventy diabetic subjects (35 type 1 and 35 type 2) with stable glycemic control and 33 healthy control subjects were evaluated using PCR and direct sequencing of the FN3K gene. Denaturing high performance liquid chromatography (DHPLC) was used in controls for screening for the presence of the genetic variants previously found in diabetic patients. Results: Seven different genetic variants were identified, five of them already reported and two new: the p.R187X and p.Y239C mutations identified in two females affected by T2DM. No significant association was found between certain polymorphisms and diabetes conditions. Preliminary haplotype studies are also reported. With respect to genotypes, we noted that some were not present in all the investigated cohort, and some were found related to higher glycated hemoglobin compared to others, although not at a significant level, probably because of the small number of subjects investigated. Conclusions: In conclusion, this study identified two new mutations and additional variants within the FN3K gene. This is the first study on FN3K in Italy. Future work is needed to achieve a better understanding of the FN3K enzyme and its possible clinical utility in the management of diabetic patients.

Background: The determination of polymerase chain reaction (PCR) amplification product sizes of the Bcl- 2 /IgH fusion gene from follicular lymphoma (FL) provides evidence of clonal identity. Methods: The present study describes detection of Bcl- 2 /IgH fusion gene clonality utilizing a small, simple microcapillary electrophoretic chip combined with a real-time PCR method. Results: The microcapillary electrophoretic chip system effectively detects size differences among the Bcl-2/IgH fusion gene amplification products of FL from patient samples; something that is not possible using traditional gel electrophoresis. We also describe the potential of this system to utilize formalin-fixed, paraffin-embedded tissue samples sectioned on charged slides. Conclusions: The simple detection of Bcl-2/IgH fusion gene clonality using a microcapillary electrophoretic chip provides reliable information for monitoring minimal residual disease of FL, and can be an effective tool for use in clinical laboratories.

Background: Interest in biomarker patterns and disease has led to the development of immunoassays that evaluate multiple analytes in parallel while using little sample. However, there are no current standards for multiplex configuration, validation, and quality. Thus, validation by platform, population, and question of interest is recommended. We sought to determine the best blood fraction for multiplex evaluation of circulating biomarkers in post-menopausal women, and to explore body composition phenotype discrimination by biomarkers. Methods: Archived serum and plasma samples from a sample of healthy post-menopausal women with the highest (n=9) and lowest (n=11) percent lean mass, as determined by dual-energy X-ray absorptiometry, were used to measure 90 analytes using bead-based, suspension multiplex assays. Replicates of serum and plasma were analyzed in a random selection of four of these individuals. Results: Ninety percent of the analytes were detectable for ≥50% of samples; when limited to these well detected analytes, mean replicate correlations for serum and plasma were 0.87 and 0.85, respectively. Serum had lower error rates discriminating phenotypes; seven serum vs. two plasma analytes discriminated extreme body phenotypes. Conclusions: Serum and plasma performed similarly for the majority of the analytes. Serum showed a slight advantage in predicting extreme body composition phenotypes in postmenopausal women using parallel evaluation of analytes.

Background: Tacrolimus (Tac) is an immunosuppressive drug used to prevent post-transplant (PT) organ rejection. Continuous Tac monitoring is necessary to adjust the dose and prevent toxicity or rejection. Tac is metabolized by cytochrome-P450 (CYP) enzymes, and variation at the CYP and other drug metabolizing enzymes could influence Tac bio-availability and dose requirements. Our aim was to define the effect of DNA variants at 16 drug metabolising enzymes on Tac dose in patients with kidney transplants. Methods: The REDINREN Pharmacogenetics Project was a multicenter study designed to evaluate the effect of DNA polymorphisms on Tac dose requirements. A total of 200 patients who received a first cadaveric kidney and Tac as primary immunosuppressive drug were genotyped for 96 DNA polymorphisms on 16 genes. Significant associations were further replicated in a second group of 200 patients. The Tac daily dose was adjusted to achieve a blood concentration of 10–15 ng/mL in the period 0–3 months PT, and 5–10 ng/mL thereafter. The dose of tacrolimus dose and blood concentrations were compared between genotypes at 1 week, 6 months, and 1 year PT. Results: The CYP3A5 genotype (SNP rs776746) was the strongest predictor of Tac dose requirements. Patients who were CYP3A5*3*3 (CYP3A5 non-expressors) received significantly higher Tac dose at 1 week, 6 months, and 1 year PT (p<0.0001). At 1 week, 41% of the CYP3A5 non-expressors achieved target blood concentrations compared to 26% of the CYP3A5 expressors (p=0.007). We also found a significant effect of CYP3A4 genotype (SNP rs2740574) on Tac dose requirements in patients who were CYP3A5 non-expressors. None of the other polymorphisms were related to Tac dose requirements or modified the effect of the CYP3A5 genotype. Conclusions: rs776746 ( CYP3A5) and rs2740574 ( CYP3A4 ) were the only SNPs associated with Tac dosage. The genotyping of these polymorphisms could be a useful pharmacogenetic tool to determine the Tac dose immediately after transplantation.

Background: The adoption of Quality Indicators (QIs) has prompted the development of tools to measure and evaluate the quality and effectiveness of laboratory testing, first in the hospital setting and subsequently in ambulatory and other care settings. While Laboratory Medicine has an important role in the delivery of high-quality care, no consensus exists as yet on the use of QIs focussing on all steps of the laboratory total testing process (TTP), and further research in this area is required. Methods: In order to reduce errors in laboratory testing, the IFCC Working Group on “Laboratory Errors and Patient Safety” (WG-LEPS) developed a series of Quality Indicators, specifically designed for clinical laboratories. In the first phase of the project, specific QIs for key processes of the TTP were identified, including all the pre-, intra- and post-analytic steps. The overall aim of the project is to create a common reporting system for clinical laboratories based on standardized data collection, and to define state-of-the-art and Quality Specifications (QSs) for each QI independent of: a) the size of organization and type of activities; b) the complexity of processes undertaken; and c) different degree of knowledge and ability of the staff. The aim of the present paper is to report the results collected from participating laboratories from February 2008 to December 2009 and to identify preliminary QSs. Results and conclusions: The results demonstrate that a Model of Quality Indicators managed as an External Quality Assurance Program can serve as a tool to monitor and control the pre-, intra- and post-analytical activities. It might also allow clinical laboratories to identify risks that lead to errors resulting in patient harm: identification and design of practices that eliminate medical errors; the sharing of information and education of clinical and laboratory teams on practices that reduce or prevent errors; the monitoring and evaluation of improvement activities.

Background: Physician requests for additional testing on an existing laboratory specimen (add-ons) are resource intensive and generally require a phone call to the laboratory. Verbal orders such as these have been noted to be associated with errors in accuracy. The aim of this study was to compare a novel computerized system for add-on requests to the prior verbal system. Method: We compare the computerized add-on request system to the verbal system with respect to order completeness and workflow. Results: We demonstrate that the computerized add-on system resulted in the complete in-laboratory documentation of the add-on request 100% of the time, compared to 58% with the verbal add-on system. In addition, we show that documentation of a verbal add-on request in the electronic medical record (EMR) occurred for 4% of requests, while in the computerized system EMR documentation occurred 100% of the time. We further demonstrate that the computerized add-on request process was well accepted by providers and did not significantly change the test mix of the add-on requests. Conclusions: In computerized physician order entry (CPOE) implementations, add-on order functionality should be considered so these orders are documented in the EMR.

Background: The poor comparability of growth hormone (GH) results obtained using commercially available methods, is partly due to standard preparations used in calibration. The system relies on the use of the International Reference Preparation (IRP) international standard (IS) 80/505, of human pituitary origin, containing all GH isoforms. Recently, a 22K recombinant GH isoform IRP IS 98/574 was commercialized. Our aim was to evaluate the influence of both calibrators on GH results. Methods: GH concentration in 97 serum samples from children undergoing a growth hormone releasing hormone+arginine stimulation test was measured using Siemens IMMULITE electro-chemiluminescence method, calibrated with both IS 80/505 and IS 98/574 (GRH Growth hormone-Recombinant 98/574-kit). Results: Comparison of our results obtained with the two sets of calibrators showed good correlation, although we found higher percentage variation (var%) than that stated by Siemens. The mean var% value was confirmed when all results were sub-divided into subgroups based on both high and low GH concentrations. Conclusions: Since the GH assay is influenced by a variety of binding proteins, isoforms and conversion factors, standardization of the assay is strongly required. In Italy, the Agenzia Italiana del Farmaco 39 note provides GH laboratory values which are useful for therapy. On the basis of our results, we therefore propose to adjourn these GH values in order to ensure better management of patients with GH-related disorders.

Background: The Luminescent Oxygen Channeling Immunoassay (LOCI ® ) technology is a well-established homogeneous assay format that allows for fast, accurate, and highly sensitive quantitation of analytes. We set out to develop and prove a novel concept to establish a LOCI format that should principally allow for the determination of the activity of coagulation factors and anticoagulants of clinical relevance. Methods: The concept is based on the linkage of LOCI nano-beads by a peptide that can be cleaved by a coagulation factor. To prove the principle, we used a peptide that can be cleaved by thrombin. Results: We were able to show that coagulation activation of plasma or whole blood samples that were combined with the LOCI components degraded the thrombin-sensitive peptide and consequently, led to a reduction of the LOCI signal. Signal reduction was proportional to the amount of active thrombin generated. The research prototype assay allowed for the detection of factor deficiencies in both the extrinsic and intrinsic coagulation pathways, and for the quantification of hirudin, a direct thrombin inhibitor. Conclusions: Taken together, we conclude that the LOCI technology has the potential for extension to functional blood coagulation assays.

Background: Trefoil peptides are 7–12 kDa molecules, se-creted by a variety of mucin-producing epithelial cells from different tissues and believed to be essential for protection and maintenance of gastrointestinal mucosa. Data on concentrations of trefoil peptides in secretions are limited. Methods: We validated in-house ELISA assays, developed for measurement of trefoil peptide concentrations (TFF1, TFF2 and TFF3) in serum, for use with saliva and cervical mucus. Saliva from healthy individuals (n=30), and cervical mucus as well as blood collected three times during the menstrual cycle from healthy women (n=18) were analyzed. Results: Recovery of all trefoil peptides in the initial supernatants of saliva and (cervical mucus) were 86 and (92)% or more. Recovery of exogenously added trefoil peptides was 93 and (95)% or more. Western blotting showed that antibodies used in the TFF3-ELISA assay recognised one molecule of the same size as TFF3 in both saliva and cervical mucus. Median concentrations of TFF1, TFF2 and TFF3 in saliva and (cervical mucus) were 2.7 (2.7), 0.08 (0.58) and 14 (430) nmol/g protein, with a significant decrease in concentrations in cervical mucus after ovulation. Serum concentrations resembled previously measured values in blood donors and showed no cyclic change. Conclusions: Previously established ELISA assays can be employed for measurement of trefoil peptides in saliva and cervical mucus. TFF3 was the predominant trefoil peptide in both saliva and cervical mucus, and TFF3 in cervical mucus represents the highest concentration measured in a biological fluid to date.

Background: Stocks of 95/560, the 1st International Standard for sex hormone-binding globulin (SHBG), are runn-ing out, and 08/266 has been prepared as a replacement. We compared the steroid binding capacities of 95/560 and 08/266. Methods: 95/560 and 08/266 stored at –20°C, and accelerated thermal degradation samples of 08/266 were subjected to gelfiltration. Binding of the SHBG-containing fractions to a dihydrotestosterone derivative was then investigated using a surface plasmon resonance biosensor. The SHBG content of the gelfiltration fractions was determined with an immunoassay. Steroid binding capacity of each standard was then calculated as the mean of the ratio of biosensor binding/SHBG concentration. Affinity constants for the SHBG steroid interaction were calculated. Results: Maximum achievable biomolecular interactions were lower for 95/560 than for the 08/266 preparations. 95/560 exhibited steroid binding capacity only half as high as any of the novel standards, as well as a lower affinity constant for the SHBG steroid interaction. No significant differences could be observed between the samples of 08/266 stored at different temperatures. Conclusions: The steroid binding capacity of 08/266 is two times higher than that of 95/560. Steroid binding of lyophilized 08/266 is preserved at storage temperatures of up to 45°C for at least 6 months.

Background: Immunoassays are susceptible to interferences by anti-hormone antibodies, heterophilic antibodies or rheumatoid factor (RF). Methods: We report a case of levothyroxin overdose because of gross overestimation of thyroid-stimulating hormone (TSH) by chemiluminescent and IRMA assays. Alternate assays were performed and heterophilic antibodies blocking tubes were used. Results: Analytical investigations revealed: i) non-linear concentrations of TSH after serum dilutions, ii) decreased TSH concentrations after removal of heterophilic antibodies, iii) appropriately decreased TSH concentrations in alternate TSH assays and iv) identification of increased concentrations of RF. Conclusions: The presence of RF may be responsible for false determination of TSH concentrations preventing monitoring of TSH.

Background: Gene amplification of HER2 (human epidermal growth factor receptor 2) is a well-known phenomenon in various cancers. However, little is known about the mechanism of the gene amplification phenomenon itself. Autoantibodies to cellular receptors have been described in several cancer types. We hypothesised that autoantibodies against HER2 might have a stimulatory capacity and could be the cause of the HER2 gene amplification phenomenon. To investigate this, we developed a test for the detection of autoantibodies against HER2 in serum (S-HER2Ab). Methods: Blood and tissue samples were collected from 311 women consecutively admitted for surgical treatment of primary breast cancer. Paraffin embedded tissue sections were analysed by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). HER2 protein concentrations in tissue were determined in 115 patients. Circulating extracellular domain of HER2 (S-HER2) was measured using the Advia Centaur (Siemens AG, Munich, Germany). Analysis for autoantibodies was developed on an ImmunoCAP 100 (Phadia AB, Uppsala, Sweden) with an automated Fluorescent Enzyme Immuno Assay. Results: Of 311 women, 55 (17.7%) had HER2Ab and 51 (16.4%) showed amplification of the HER2 gene determined by IHC/FISH. Eleven women had detectable S-HER2Ab as well as HER2 gene amplification, but no statistically significant correlation was found between the two phenomena. A significantly higher level of S-HER2Ab was found both in HER2 gene-amplified and non-amplified breast cancer patients compared to an age-matched healthy control group. No statistically significant difference in presence or concentration of S-HER2Ab was found in HER2 gene-amplified vs. non-amplified breast cancer. Conclusions: S-HER2Ab can be measured accurately with the ImmunoCAP 100. There is an increased prevalence and concentration of S-HER2Ab in breast cancer patients but no correlation with HER2 gene amplification. We conclude that autoantibodies against HER2 do not seem to be the cause of HER2 gene amplification.

Background : In cancer tissue, altered glycosylation of proteins is observed. There are some typical changes; for example, sialyl-Lewis a/x glycoforms are more abundant in many types of cancers. The current study investigated the differences in glycosylation of proteins between neoplastic and healthy human salivary glands. Methods : Sugar structures on proteins with a molecular mass above 30 kDa were determined by enzyme-linked immunosorbent assay (ELISA) with biotinylated lectins. Results : The expression of sialic acid in cancer tissues was higher in comparison with healthy ones. The same observations were revealed for Fuc α1-6, α1-2, T, Tn antigens and α1-6 mannose. Conclusions : Glycosylation of proteins in cancer salivary gland tissues is altered in comparison with healthy tissue.

Background: Approximately 40% of HIV infected patients have chronic meningitis at various stages during the infection, 59% are asymptomatic. This is a diagnosis of exclusion and a confounding factor in cerebrospinal fluid (CSF) analysis, any other causes of chronic meningitis by opportunistic or co-infection must be ruled out. The aim of this study was to analyze CSF lactic acid (LA) as an adjuvant biomarker in chronic meningitis due to HIV. Methods: CSF LA was quantified in 223 CSF samples by the Dimension AR (Dade Behring, Deerfield, IL, USA), distributed into nine groups: 1) HIV positive with an increase in CSF WBCs (n=17); 2) HIV positive with normal CSF (n=20); 3) enterovirus meningitis (n=33); 4) Herpesviridae meningoencephalitis (n=30); 5) fungal meningitis (n=25); 6) tuberculosis (TB) meningitis (n=17); 7) toxoplasmosis (n=18); 8) neurosyphilis (n=6); 9) control group (n=57). Results: CSF LA (median; IQR) was higher in samples with TB meningitis (5.5; 2.9–7.5 mmol/L) and Cryptococcus neoformans meningitis (3.9; 2.7–5.8 mmol/L) compated with samples with HIV chronic meningitis (1.7; 1.4–1.9 mmol/L) and other groups (p≤0.0001). For the diagnosis of HIV chronic meningitis, using a cut-off of 3.5 mmol/L, CSF LA showed high sensitivity and negative predictive value, although low specificity. Conclusions: CSF LA helps to discriminate between C. neoformans or TB meningitis and HIV chronic meningitis: CSF LA can be included with the methods currently used to identify these specific pathogens, though it does not replace them. It is rapid, inexpensive and easy to perform, and can be used in developing countries.

Background: The aim of this work has been to study the association between plasma asymmetric dimethylarginine (ADMA) concentrations and carotid stenosis in a group of 64 patients undergoing carotid endarterectomy (CEA). Methods: Arginine, ADMA and symmetric dimethylarginine (SDMA) were measured using capillary electrophoresis with UV detection. An evaluation of plasma concentrations of total cysteine (tCys) and total homocysteine (tHcy) was also performed. Results: Pearson’s analysis show a positive correlation between ADMA and carotid stenosis (r=0.37, p=0.003), which is also confirmed after stepwise multiple linear regression analysis. ADMA plasma concentrations were significantly associated with tHcy (r=0.40, p=0.001) and to a lesser extent, even if not significantly, with tCys (r=0.23, p=0.07). Conclusions: Our data suggest that plasma ADMA is involved in carotid narrowing after CEA intervention. This suggests that this molecule may have an important role in the events that lead to stenosis.

Background: Increased concentrations of asymmetric dimethylarginine (ADMA) have been detected in patients with cardiovascular risk factors. In addition, high baseline plasma concentrations of ADMA have been shown to be an independent predictor of adverse outcomes in various disorders. This study aimed to evaluate the impact of admission ADMA concentrations on microvascular flow after primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI). Methods: Blood samples from 39 patients with STEMI were collected at admission to measure the concentrations of ADMA and other cardiovascular risk factors including inflammatory markers and the lipid profile. Primary PCI was performed in patients with STEMI. The maximum ST-segment elevation in standard 12-leads electrocardiogram (ECG) before and 24 h after PCI was measured, and patients were stratified as complete or incomplete ST-segment resolution (STR). Results: Twenty-five patients had complete (≥70%) and 14 incomplete (<70%) STR. In patients with incomplete STR, ADMA concentrations were significantly higher than that seen in others (0.447±0.215 μmol/L vs. 0.310±0.134, p=0.019), and was independently associated with STR. Conclusions: Admission concentrations of ADMA appeared to be useful for early risk stratification in reperfusion therapy for acute myocardial infarction.

Background: Uric acid is a novel cardiovascular disease (CVD) factor, but its use as an independent risk factor for CVD remains controversial. Here, we examined the correlation between Framingham risk score (FRS) and serum uric acid concentrations in asymptomatic Korean adults. Methods: This cross-sectional study was performed on 8035 Korean adults. Besides FRS, we measured body mass index, fasting blood glucose, homeostasis model assessment of insulin resistance, creatinine, γ-glutamyltransferase, the lipid profile, uric acid, high-sensitive C-reactive protein, and the white blood cell count. All subjects were placed into one of three risk groups according to their FRS. Results: All CVD related factors were significantly different in the three FRS groups. The increments of uric acid in-creased significantly FRS from the 10-year risk 0%–9% group to the >10% group after adjusting for other CVD-related factors using ordinal logistic regression analysis. Analyses of the three age groups showed similar effects. Conclusions: An increased uric acid concentration is associated with an increase in coronary heart disease risk calculated from the FRS, and doctors need to pay attention to this CVD risk in apparently healthy adults with hyperuricemia.

Background: Hyperuricemia may underlie obesity and related disorders, but the impact of weight reduction and metformin on serum uric acid (sUA) in Caucasian children/adolescents is unknown. Methods: One hundred and thirteen children/adolescents were enrolled (83 completed) into 1-year weight reduction program (diet+exercise) without or with metformin. Anthropometric and biochemical measurements were conducted at baseline and at the end of follow-up (13±3 months). Results: sUA decreased in 86% females and 67% males. Significantly more patients substantially (≥10%) reduced their sUA than body mass index (BMI)%. In females, sUA decreased regardless of type of intervention, but more markedly in the metformin group, and ΔsUA correlated positively with ΔBMI%, ΔWHtR (waist-to-height ratio), Δinsulin, ΔHOMA (homeostasis model of assessment), and Δtriglycerides/high density lipoprotein (HDL), but correlated negatively with baseline sUA, HOMA, insulin, and triglycerides/HDL. Of these, metformin treatment, baseline sUA, and ΔBMI% were independent predictors of sUA reduction, explaining 77% of data variability. In males, sUA reduction was significant in the metformin group only, and negatively correlated with ΔWHR (waist-to-hip ratio), ΔWHtR, Δleptin, baseline sUA, and waist circumference. Of these, baseline sUA and ΔBMI% were independent predictors of sUA reduction, explaining 69% of data variability. Except for sUA, females reduced their BMI%, waist circumference, triglycerides, triglycerides/HDL and increased HDL, while males reduced total cholesterol. Conclusions: A longitudinal weight reduction program encompassing diet/exercise with or without metformin was more efficient in reducing sUA than weight and its effect on sUA and other metabolic parameters differed between genders. Weight loss did not condition sUA reduction, which was strongly dependent on baseline levels. The sUA reducing effects of metformin may contribute to its effects on blood pressure-lowering and endothelial function-improving properties in females.

Background: A 35-year-old female presented with complaints of tiredness, shortness of breath and recent onset of chest pain. The cardiac troponin I (cTnI) concentration was elevated at 6.4 μg/L (Abbott Architect reference value: <0.03 μg/L) with a normal ECG. Physical examination, radiological imaging and routine laboratory investigations did not provide an explanation for the elevated cTnI concentration. Methods: Use of different troponin assays, dilutions with assay diluent, addition of mouse serum, polyethylene glycol (PEG) precipitation and gel filtration chromatography (GFC) were used to investigate possible interference. Results: Troponin concentrations were below the level of detection when measured using all other troponin immunoassays. Serial dilutions of sample and addition of mouse serum did not alter the results. However, PEG precipitation and GFC showed the presence of a high molecular weight immunoreactive protein. Using GFC and protein-A IgG precipitation, the interference could be identified as a macrocomplex containing IgG and (fragments of) cTnI. Conclusions: We report a false positive cTnI result caused by a true macrotroponin, containing IgG and (fragments of) cTnI. This macrotroponin was only immunoreactive in the Abbott Architect cTnI immunoassay. Clinicians should be aware of analytical interference when troponin results are constantly elevated in the absence of (non)coronary causes of an increased troponin.