Annals of Clinical Biochemistry最新文献

BackgroundWe previously reported that salivary testosterone (Sal T) decreased following a morning meal but concluded that this decrease could be a postprandial effect or an inherent circadian rhythm or both. Since no studies describing diurnal variations in Sal T have considered the effect of meals, we investigated the temporal variation of Sal T independent of food consumption.MethodsSalivary samples were collected from 17 males at 09.00 h, 10.00 h, and 11.00 h and then at 22.00 h, 23.00 h, and 24.00 h following an 8 h fast for each collection period.ResultsMean (standard deviation) Sal T concentrations were 191.2 (56.68) pmol/L at 09.00 h, 174.2 (53.29) pmol/L at 10.00 h, 168.1 (52.61) pmol/L at 11.00, 120.2 (46.04) pmol/L at 22.00 h, 130.3 (35.72) pmol/L at 23.00 h and 125.1 (29.75) pmol/L at 24.00 h. Sal T at 09.00 h was higher (P < .05) than at all other time points. Sal T at 10.00 h was similar (P = .65) to that at 11.00 h and both were higher (P < .05) compared to all evening time points. Although some patients exhibited a nadir in Sal T at 22:00 followed by an increase, overall evening levels were not significantly different (P > .80).ConclusionWe report an inherent circadian rhythm in Sal T with higher levels in the morning than evening and report for the first time that it is independent of food consumption.

BackgroundThe foetal anomaly screening (FAS) programme in England screens for trisomies 21, 18 and 13 using a combination of maternal age and biochemical and ultrasound markers in a multivariate Gaussian approach to calculate the chance of a foetal trisomy. The screened population is divided into higher and lower chance categories using a 1 in 150 cut-off. A truncation of 1 in 5000 is used for the lowest chance results.A series of postal strikes resulted in delay to specimen delivery and necessitated rebleeding of hundreds of affected clients across England. The effect of delay in processing specimens was investigated based on the final chance reported, rather than the effect on the individual biomarkers used in the chance calculation.MethodsThe FAS chances from samples delayed in postal strikes were compared against those from repeat samples from the same patients to determine the absolute effect on the final chance reported rather than the individual biomarkers.ResultsA total of 119 of 120 chances reported remained in the same high/low chance category.ConclusionMarker concentrations are affected by delayed separation, but the effect on calculated chance is only significant in those close to the 1 in 150 cut-off. There is little benefit in rebleeding clients at very low chance or at very high chance as this leads to a delayed result and the possibility of missed screening for some affected pregnancies.

BackgroundPhosphatidylethanol (PEth) is formed in erythrocyte membranes after alcohol consumption. When abstaining, the PEth level falls with a rate proportional to its concentration, and a short apparent PEth half-life supports abstinence. We here derive algorithms for calculating unbiased half-lives and confidence intervals (CIs).MethodsPEth was measured using Acquity UPC2-MS/MS systems in clinical blood samples from out-patients. We identified 6989 individuals having taken two or more PEth samples within 28 days. One measurement pair was randomly selected from everyone. We derived methods for and calculated PEth half-lives and corresponding 95% CIs for exact, rounded, and truncated data, on closed form, Monte Carlo methods and No-U-turn sampling.ResultsThe peak of the PEth half-life was at 8.62 days. Peak PEth half-life was 8.72 days for men and 8.47 days for women (P = 0.028) and on age: 8.55 days for age 18-39 years, 8.56 for age 40-59 years and 8.87 for 60+ years (P = 0.026). PEth concentration did not significantly affect half-life. CIs on a closed form performed excellently on exact data, with misclassification of abstinence for 16 out of 6989 observations (0.23%). When rounding or truncating data, misclassification occurred using Monte Carlo methods in 104 (1.5%) and 127 (1.8%) of the observations and using closed form algorithms in 855 (12.2%) and 777 (11.1%).ConclusionUnbiased PEth half-lives and CIs can be calculated and put into use in laboratory information systems. Rounding or truncating data used for PEth half-life calculation widened CIs with misinterpretations of alcohol abstinence.

BackgroundThis study aimed to identify laboratory parameters that could optimize the PLASMIC score, thereby improving its diagnostic accuracy for thrombotic thrombocytopenic purpura (TTP).MethodsWe performed a retrospective analysis of 136 patients with suspected TTP who had available ADAMTS-13 activity measurements. Patients were stratified into two groups based on ADAMTS-13 activity: a TTP group (n = 49) and a non-TTP group (n = 87). Routine laboratory parameters-including hemoglobin (HGB), red blood cell distribution width-standard deviation (RDW-SD), mean corpuscular volume (MCV), platelet count (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBIL), indirect bilirubin (IBIL), lactate dehydrogenase (LDH), creatinine (CR), urea (UREA), international normalized ratio (INR), and D-dimer-were compared between groups. Statistically significant parameters were selected as candidate variables to refine the PLASMIC score. The diagnostic performance of the modified model was evaluated using receiver operating characteristic (ROC) curve analysis.ResultsSix parameters-HGB, PLT, ALT, RDW-SD, IBIL, and LDH-demonstrated significant differences between TTP and non-TTP patients. Multivariate logistic regression identified RDW-SD, PLT, and LDH as independent predictors of TTP. Based on these findings, we revised the PLASMIC score by substituting MCV with RDW-SD. The modified model exhibited a higher area under the curve (AUC) (0.907 vs 0.817) while maintaining sensitivity (95.9%) and improving specificity (70.1% vs 65.9%) compared to the original.ConclusionThe modified PLASMIC score model may improve diagnostic accuracy for TTP in similar patient populations, but requires external validation in diverse cohorts to confirm its broader utility.

ObjectivesAcidification of urine samples has long been used as a method of preservation to enhance analyte stability. However, there are inherent safety risks to staff and patients when acid preservatives are used. The Association of Laboratory Medicine National Audit Committee sought to assess urine acidification practices in NHS laboratories.MethodAn 11 question survey was sent to all Association of Laboratory Medicine members for completion between 24th January 2023 and 24th February 2023 and data analysis performed using Microsoft Excel. For a variety of analytes, laboratories were asked to detail the type of recommended and accepted collection containers, whether 24 h and/or spot urine samples were accepted, if preservative was added to samples on receipt if not collected with preservative and the storage conditions for unpreserved samples.Results69 laboratories responded. Safety information was provided to users by the majority of laboratories and 88% of laboratories would pH test samples prior to sending them to a referral laboratory if acidification was a prerequisite. Variation was noted in quoted time of sample stability when refrigerated. Laboratories provided answers about specific tests - sodium, potassium, osmolality, calcium, magnesium, phosphate, creatinine, Bence Jones protein, total protein, urate, citrate, oxalate, cysteine, catecholamines, metanephrines, 5-HIAA, VMA/HMMA, copper, amino acids, organics acids and glycosaminoglycans.ConclusionsThere is significant variation in the use of acid as a preservative for urine samples throughout NHS laboratories as well as historical requirements for urine acidification for certain analytes which evidence has indicated is no longer a requirement.

BackgroundCystatin C (CysC) is a biomarker used to assess kidney function. Produced by all nucleated cells, it is freely filtered by the glomeruli, and its serum levels increase rapidly following kidney injury. Establishing reference intervals (RIs) is fundamental for the clinical application of CysC, as these parameters vary with geographic region and ethnic origin. This study aimed to determine RIs for CysC in healthy children aged 5-11 years from public schools in Santa Maria, southern Brazil.MethodsWe enrolled 134 healthy children (aged 5-11 years, both sexes). Cystatin C levels were measured via immunoturbidimetry, and RIs were defined by the 2.5th and 97.5th percentiles.ResultsThe RI for serum CysC was 0.59 to 1.10 mg/L. Sex-specific analysis revealed CysC RIs of 0.53-1.10 mg/L for females and 0.61-1.10 mg/L for males.ConclusionsThese findings provide valuable insights for paediatric clinical decision-making in a previously unstudied population and underscore the need for further research to validate and refine the clinical applications of CysC in paediatrics.

BackgroundMeasurement of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and left ventricular ejection fraction (LVEF) are used in diagnosing heart failure (HF). The main aim was to explore the correlation between NT-proBNP and LVEF.MethodsPatient data for 14,962 patients were extracted from medical records and national registries and compiled in the Swedish DEMONSTRATE database. HF phenotype was categorized according to LVEF level: HF with reduced EF (≤40%, HFrEF); HF with mildly reduced EF (41-49%, HFmrEF); HF with preserved EF (≥50%, HFpEF). Spearman's rank was employed for correlation analysis and ROC curves for discrimination and classification.ResultsNT-proBNP correlated negatively with LVEF level (r = -0.40) and positively with age (r = 0.49), creatinine (r = 0.35), and cystatin C (r = 0.53). Individuals with an HF diagnosis were more likely to have higher NT-proBNP levels compared to those without. The association between NT-proBNP and LVEF remained statistically significant (P < .0001) also after adjusting for age and kidney function estimates (r = -0.20). NT-proBNP discriminated well between HFrEF (AUC = 0.80) and HFpEF (AUC = 0.78). In discriminating the presence of an HF diagnosis, NT-proBNP (AUC = 0.81) outperformed LVEF (AUC = 0.75). However, on an individual level the correlation between LVEF and NT-proBNP was modest.ConclusionsNT-proBNP levels increase when LVEF deteriorates but with large inter-individual differences. Further research is needed, but these findings show potential in optimizing the use of LVEF with the aid of sequential analysis of NT-proBNP as a complementary diagnostic and prognostic tool to enhance assessment of cardiac function.