Scandinavian Journal of Clinical & Laboratory Investigation最新文献

Elevated triglyceride (TG) levels, common in hypertriglyceridemia, can significantly interfere with electrolyte analysis, particularly by the indirect ion-selective electrode (ISE) method. However, comprehensive data on the concentration-dependent measurement differences for potassium, sodium and chloride, along with validated corrective algorithms, are lacking. This study assessed the discrepancies in these electrolytes between direct and indirect ISE methods in serum samples with high TGs, while developing correction formulas for the indirect ISE. A total of 154 serum samples with high TGs and 50 control serum samples were analyzed in this retrospective cross-sectional study. Triglycerides were measured using colorimetric methods on the Roche Cobas 8000 analyzer (Roche Laboratories, Basel, Switzerland). Sodium, potassium and chloride were measured with direct ISE (Vitros 5600 Integrated System; Ortho-Clinical Diagnostics, Inc., Raritan, NJ) and indirect ISE (Roche Cobas 8000 analyzer). Our results revealed significant negative biases in the indirect ISE, particularly in samples with TG >20.00 mmol/L. For TG levels between 20.01 and 30.00 mmol/L, the negative biases for sodium, potassium and chloride were -2.31%, -3.86% and -4.58%, respectively. Notably, in the subgroup with TG >60.00 mmol/L, the negative biases reached their maximum values: -12.05% for potassium, -6.88% for sodium, and -10.59% for chloride. Additionally, linear correction formulas that aligned indirect results with direct measurements were developed and validated. Post-correction, differences fell within clinical thresholds (Diff_Na of |4| mmol/L, Diff_Cl of |4| mmol/L, Diff_K of |0.5| mmol/L). Collectively, high TGs impact electrolyte measurements by indirect ISE, but the correction formulas might mitigate the discrepancies. These correction formulas were platform-specific, and their generalizability to other analytical systems requires further investigation.

Familial hypocalciuric hypercalcemia (FHH) is a genetically heterogeneous autosomal dominant disorder of calcium homeostasis, which is usually asymptomatic and characterized by low or normal phosphorus, inappropriately normal or elevated PTH, and low fractional excretion of calcium (FECa) in addition to hypercalcemia. Loss-of-function mutations in the G protein subunit alpha 11 (GNA11) gene, an important downstream signaling partner of the Calcium-sensing receptor (CaSR), cause FHH type 2. We reviewed the GNA11 gene-associated FHH type 2. A 14-year-old male was referred due to hypercalcemia (2.89 mmol/L). Slightly elevated PTH (7.95 pmol/L), but normal phosphorus (1.19 mmol/L), alkaline phosphatase (271 U/L), magnesium (0.95 mmol/L), and albumin (43 g/L) levels were detected. The FECa was found to be low when serum calcium was high (FECa was <0.01%, and <0.01% on two separate tests). A homozygous c.301T > C, p.Y101H variant was detected in the GNA11 gene. The same variant was detected heterozygous for both parents. While the calcium levels of the mother and father were normal, their spot urinary FECa was found low (Ca: 2.47 mmol/L, FECa: <0.01%, and Ca: 2.45 mmol/L, FECa: 0.01%, respectively). Hypocalciuria without hypercalcemia can be detected in cases heterozygous for the GNA11 gene mutation. Severe hypercalcemia may not occur in homozygous cases.

As neuroblastoma is a highly heterogeneous pediatric solid tumor, it is essential to select appropriate reference genes to compare the concentration of circulating free DNA (cfDNA) between patients with neuroblastoma and healthy individuals. cfDNA was extracted from peripheral blood and quantified using quantitative Polymerase Chain Reaction (qPCR). The stability of candidate reference genes (RGs) was analyzed using the ΔCt method, geNorm, NormFinder, and BestKeeper. The results from these four algorithms were integrated using the RefFinder tool to generate a comprehensive stability ranking and assess the stability of these candidate RGs across different sample groups. Alpha hemoglobin stabilizing protein (AHSP) and Hypoxanthine-Guanine Phosphoribosyltransferase 1 (HPRT1) exhibited the highest stability, whereas Beta-2-microglobulin(B2M) and HBS1-like protein(HBS1L) demonstrated the lowest stability. qPCR of cfDNA from patients with neuroblastoma revealed differences in the stability of various reference genes. Prioritizing reference genes with better stability may facilitate more accurate detection of intergroup differences in the samples.

Cystatin C was identified as a marker of glomerular filtration rate (GFR) in 1979, and the parallel analysis of cystatin C and creatinine led to the identification of shrunken pore syndrome (SPS) - a new kidney disorder - in 2015. Since then, it has been shown that cystatin C in many aspects is superior to creatinine as a marker of GFR and cardiovascular risk. SPS, an entity within the selective glomerular hypofiltration syndromes (SGHS), has been demonstrated to be associated with a strong increase in morbidity and mortality in several populations. Despite the seriousness of SPS and SGHS, and the availability of potential treatments, many patients with these conditions remain undiagnosed, due to the limitations of the international Kidney Disease Improving Global Outcomes Organization (KDIGO) guidelines. Given the significant clinical advantages of cystatin C in diagnosing and treating kidney disorders, there is a need to expand the KDIGO guidelines to include cystatin C measurements alongside creatinine at least in the initial patient evaluation but also in follow-up evaluations. This would improve the early detection and management of patients with kidney diseases, ultimately enhancing patient outcomes. The present discourse summarizes the development of this understanding from the original observations in 1979 and 2015 to the latest findings.

Objectives: To develop and present simple visual and descriptive summary measures of agreement in method comparison studies with replicated measurements and to discuss detection of drift in method comparison studies. Summary measures may serve as an exploratory data analysis guiding further agreement and decision analysis of two methods using the Bland and Altman method and mixed-effects modeling. Materials and methods: The methodological approach is illustrated using freely available clinical datasets from two published method comparison studies with repeated measurements on each subject. Results: With the use of ellipses and a numerical ideality index as summary measures for each subject with paired measurements from two clinical methods, it is possible to quickly decode a dataset's intra- and interindividual variation, differential and proportional bias, possible drift, and the number of measured subjects in clinically relevant areas for the two methods. Conclusion: Simple and intuitive exploratory method comparison analysis can be performed and interpreted even for relatively large datasets prior to more advanced statistical analysis of method comparisons using data with replicated measurements.

This study investigated the preanalytical stability of acetylcholine receptor antibodies (AChRAb) in patient samples, a crucial biomarker for diagnosing Myasthenia Gravis (MG). The objective was to evaluate the impact of delayed centrifugation, storage temperature, and repeated freeze-thaw cycles on the accuracy of AChRAb test results. Blood samples were collected from nine MG patients, and four stability studies were conducted. These studies examined: (I) the effect of delayed centrifugation on whole blood (up to 7 h at room temperature), (II) storage of serum at room temperature (up to 7 days), (III) storage of serum at -20 °C (up to 26 weeks), and (IV) the impact on serum of repeated freeze-thaw cycles (up to 3 cycles). AChRAb levels were measured using ELISA, and the results were analysed for statistical variation against baseline measurements using bias limits of ±15%. The findings revealed that AChRAb remained stable for up to 7 hours of delayed centrifugation, 5 days at room temperature, 13 weeks at -20 °C, and after 3 freeze-thaw cycles. However, the antibody levels showed instability after 7 days at room temperature and 26 weeks at -20 °C, where the percentage differences exceeded acceptable limits. Analytical variation, especially at low antibody levels, and differences between ELISA kit lots were potential factors contributing to these findings. In conclusion, AChRAb shows good stability if care is taken to avoid prolonged storage and handling times to maintain diagnostic accuracy.

Suspicion of proactive drug-facilitated sexual assault (DFSA) where the perpetrator covertly administers psychoactive drugs to the victim has been reported in considerable proportions from sexual assault centers and forensic units all over the world. Substances implicated in DFSA are often referred to as 'date-rape drugs'. This study investigated toxicological findings in cases of suspected proactive DFSA presenting to the Emergency Clinic for Rape Victims in Stockholm, Sweden within 48 h of the assault. Urine samples for toxicological analysis were collected on the first visit to the clinic. During follow-up 10-14 days later, participants provided a control urine sample and reported voluntary intake of alcohol, recreational and prescription drugs in connection with the assault according to a standardized protocol. Urine samples were subjected to extensive toxicological LC-MS/MS analysis that covered common recreational drugs and >100 DFSA-associated substances. 31 out of the 55 women who presented to the clinic after a suspected proactive DFSA during the study period returned for follow-up and completed the study. Almost all women (97%) reported voluntary alcohol intake in connection with the assault, which exceeded 70 g ethanol in half of the cases. Unexpected toxicological findings were made only in five cases (16%), with the most common substance being cocaine. No typical date-rape drug was identified in cases where involuntary intake was considered likely. In conclusion, the greatest risk factor exploited by perpetrators of DFSA appears to be voluntary alcohol intoxication, while toxicological evidence of illicit drugging is rare.

Introduction: The Fibrosis-4 (FIB-4) index is a non-invasive biomarker that is widely used to assess liver fibrosis. A limitation is that the enzyme methods (aspartate transaminase (AST) and alanine transaminase (ALT)) are not specified in studies. The aim of the present study was to define reference values for FIB-4 index using Nordic Reference Interval Project data where the results for P-AST and P-ALT are traceable to the IFCC reference measurement procedures.

Material and methods: FIB-4 values from 1161 subjects (550 males and 611 females) in the NORIP study were used to calculate reference intervals for the index. The 2.5th and 97.5th percentiles for these markers were calculated according to the International Federation of Clinical Chemistry guidelines.

Results: Age (18-<39.9, 40-59.9 and 60-85 years) and sex-specific reference intervals were calculated. Of the components used to calculate the FIB-4 index the age had the greatest impact. In the cohort older than 60 years, 7.5% of the females and 18.2% of the males were above the 2.67 limit for high risk of advanced fibrosis. In the same age group 84.2% of the females and 77.6% of the males had FIB-4 values above the 1.3 limit for intermediate risk and further evaluation required. These are very high proportions which means that a very large proportion of the patients will have false positive results when testing populations with a low disease prevalence.

Conclusion: FIB-4 index increases with age, potentially leading to overestimation of fibrosis in elderly patients if age specific decision values are not used.

Analyzing the local pericardial fluid (PF) surrounding the heart can provide insights into the function of myocardial and pericardial epithelial cells. Kynurenine (KYN) metabolites have been associated with endothelial dysfunction and the progression of atherosclerosis. This study investigated the relationship between KYN pathway metabolites in serum and PF and the severity of coronary atherosclerosis, as assessed by the Syntax Score (SS). The study involved 101 patients (mean age: 60 years). Of the participants, 17% were female. KYN and its metabolite levels were measured using API SCIEX 3200 LC-MS/MS methods. Statistical analysis was performed using IBM SPSS 25.0. The mean serum levels of tryptophan (TRP), 3-hydroxykynurenine (3-HK), and 3-hydroxyanthranilic acid were significantly higher (p < 0.01) when compared to the mean PF levels. In the SS-low group, PF IDO activity was significantly higher than serum IDO activity (p = 0.040). In the SS-high group, PF IDO activity was significantly higher than serum IDO activity (p = 0.002). The mean 3-HK measurements showed significant differences between the SS groups (p < 0.05). In this study, higher IDO enzyme activity in the PF compared to systemic circulation suggests the presence of inflammatory activity in the pericardial endothelial cells. This research aimed to uncover the role of amino acid metabolism, which is poorly understood in atherosclerosis. Specifically, 3-HK, a metabolite from the KYN pathway, may contribute to the development of atherosclerosis. These findings indicate that localized kynurenine pathway activation in the PF may contribute to coronary atherosclerosis, highlighting its potential as a biomarker or therapeutic target.

Therapeutic drug monitoring (TDM) is an important tool for securing optimal treatment of drugs like beta-lactam antibiotics in hospitalized patients. Developing accurate and robust methods for quantification of the pharmacologically active fraction is needed. A LC-MS/MS assay, using ultrafiltration for selection of the non-protein bound (i.e. pharmacologically active) fraction followed by a 5.5 min chromatographic separation was developed and validated for simultaneous determination of Ampicillin (AMPI), Cefuroxime (CEFU), Meropenem (MERO) and Piperacillin (PIPE)/Tazobactam (TAZO). Inter-batch imprecision was <10%. Recovery was 88-115% from lowest level of quantification (LLOQ) to 2500 mg/L for MERO, PIPE and TAZO and LLOQ-500 mg/L for AMPI and CEFU. Storage temperature had great impact on measured concentrations, with PIPE being most instable. No effect of temperature during ultrafiltration was found for the measured beta-lactams. When evaluating one-year routine clinical use of the analysis, representing 581 (mainly ICU) patient samples, >50% of patients treated with PIPE (and AMPI), and about 30% treated with MERO and CEFU, exhibited beta-lactam levels higher than the local guidelines for maximum recommended levels. Potential toxic levels were found in several patients. We believe that the analytical method developed in this study represents an accurate measure of the pharmacologically active beta-lactam fraction. Evaluation of patient data after one-year use of the method shows higher than expected beta-lactam levels, highlighting the potential benefit of TDM. More studies are needed to determine the clinical significance of TDM in beta-lactam antibiotics.