Sigma metrics application for validated and non‐validated detecting systems performance assessment

BackgroundSigma metrics provide an objective and quantitative methodology for analytical quality evaluation of clinical laboratory. This study investigated the testing performance of validated systems and non‐validated systems based on sigma metrics, and explored the major parameters affecting the system performance.MethodsSigma metrics were evaluated by six biochemistry assays based on Beckman and Mindray validated and non‐validated systems through crossing the reagents and analyzers. Imprecision and bias were assessed for all assays based on trueness programs organized by National Centre for Clinical Laboratory. Total error allowance obtained from the Chinese Ministry of Health Clinical Laboratory Centre Industry Standard (WS/T403‐2012).ResultsThe imprecision for all systems meets the quality specifications except TP assay (2.19%) detected by Mindray non‐validated system, and the bias for four assays measured by non‐validated systems cannot fulfill the criterion, including lactate dehydrogenase (LDH), total protein (TP), triglycerides (TG), and glucose (GLU). Higher biases were detected in six assays at different levels among non‐validated and validated systems. Systems performed poorly or unacceptably for TP assay with sigma metrics lower than 3 except Mindray non‐validated system. The sigma metrics for other assays with four systems were greater than 3 except the LDH evaluated on Mindray non‐validated systems.ConclusionNon‐validated systems may introduce performance uncertainty compared with validated systems based on sigma metrics evaluation, and lower bias was provided by validated systems. The performance of non‐validated systems should be evaluated thoroughly in the clinical laboratory before they were adopted for routine use.     

Serum concentrations of small dense low‐density lipoprotein cholesterol and lipoprotein(a) are related to coronary arteriostenosis in Takayasu arteritis

BackgroundSerum small dense low‐density lipoprotein cholesterol (sdLDL‐C) and lipoprotein(a) [Lp(a)] levels are related to coronary disease, but their specific associations with coronary arteriostenosis in Takayasu arteritis (TA) have not been ascertained. This study explored the correlations between serum sdLDL‐C and Lp(a) levels and coronary arteriostenosis in TA patients as well as the degree of artery stenosis.MethodsThis retrospective study included 190 TA patients and 154 healthy subjects. TA patients were divided into three categories based on the degree of coronary stenosis: Group I, stenosis >50%; Group II, stenosis 1%–50%; and Group III, stenosis 0%. Independent risk factors for coronary arteriostenosis in TA were identified by logistic regression, followed by receiver operating characteristic curve analysis to determine the specificity and sensitivity of risk factors and Youden''s Index score calculation to determine the cutoff points.ResultsTakayasu arteritis patients had significantly higher serum levels of sdLDL‐C and Lp(a) than healthy controls (p < 0.0001). The total cholesterol, triglyceride, LDL‐C, sdLDL‐C, and Lp(a) levels and the sdLDL‐C/LDL‐C ratio in Group I were significantly higher than those in Groups II and III (p < 0.05). An elevated serum sdLDL‐C level elevated the risk of coronary arteriostenosis by 5‐fold (cutoff value, 0.605 mmol/l). An increased serum Lp(a) level increased the risk of coronary arteriostenosis by 3.9‐fold (cutoff value, 0.045 g/l). An elevated sdLDL‐C/LDL‐C ratio increased the risk of coronary arteriostenosis by 2.1‐fold (cutoff value, 0.258).ConclusionsSerum sdLDL‐C and Lp(a) levels and sdLDL‐C/LDL‐C ratio may be used as diagnostic factors for coronary arteriostenosis in TA patients.     

Frequency histograms of three high‐sensitivity cardiac troponin assays in a reference population

BackgroundCardiac troponin (cTn) values above the 99th percentile upper reference limit (URL) indicate myocardial injury. We established 99th percentile URLs for three high‐sensitivity cTn (hs‐cTn) assays (Beckman Coulter Access hs‐cTnI, Abbott STAT hs‐cTnI, and Roche Elecsys hs‐cTnT) using a healthy population in Korea.MethodsEach cTn value was measured by three assays and analyzed by dividing by gender and age.ResultsThe frequency histograms of log‐transformed cTn values for Beckman and Abbott assays exhibited a bell‐shaped distribution. The 99th percentile URLs were 9.8, 17.4, and 17.3 ng/L in the total population; 10.9/9.0, 18.9/17.0, and 18.9/17.7 ng/L in the male/female population (p < 0.001 for all three assays); and 11.2/7.2, 19.9/14.5, and 22.7/9.3 ng/L in the older/younger population (p < 0.001 for all three assays) for Beckman, Abbott, and Roche assays, respectively.ConclusionAmong the three assays, bell‐shaped distributions were observed in a frequency histogram of log‐transformed cTn values for healthy population in Beckman and Abbott assays. Also, our findings show that the 99th percentile URLs for cTn levels vary not only by gender but age.     

Distribution of urinary N‐acetyl‐beta‐D‐glucosaminidase and the establishment of reference intervals in healthy adults

BackgroundUrinary N‐acetyl‐beta‐D‐glucosaminidase (NAG) plays an important role in the early diagnosis and progression of diseases related to renal tubular injury. We detected the urinary NAG concentration, assessed the preliminary statistics of its distribution, and established reference intervals for healthy adults in China using the rate method.MethodsA total of 1,095 reference individuals (aged 20 to 79 years) met the requirements for inclusion in this study. Urinary NAG concentrations were detected using an AU5800 automatic biochemical analyzer with its matched reagents. The Kolmogorov‐Smirnov test was used to analyze the normality of the data. According to the guidelines of C28‐A3 and WS/T 402‐2012, the reference intervals of urinary NAG were established using the nonparametric percentile method (unilateral 95th percentile).ResultsThe urinary NAG data showed a non‐normal distribution. The distribution of urinary NAG was significantly different by sex and age. Therefore, the reference intervals of urinary NAG were established using the rate method: males (aged 20–59 years) <19.4 U/L (90% CI: 18.0–20.3 U/L); males (aged 60–79 years) <22.3 U/L (90% CI: 20.2–22.6 U/L); females (aged 20–59 years) <15.7 U/L (90% CI: 15.2–16.5 U/L); and females (aged 60–79 years) <21.4 U/L (90% CI: 20.3–22.3 U/L).ConclusionsWe established preliminary reference intervals of urinary NAG for healthy adults in China to provide guidance for health screening, auxiliary diagnosis, and treatment monitoring of renal tubule‐related diseases.     

迈瑞BS-800M与OLYMPUS AU2700全自动生化分析仪性能比较

目的通过对迈瑞BS-800M(后简称BS-800M)和OLYMPUS AU2700(后简称AU2700)全自动生化分析仪进行性能比较,探讨国产全自动生化分析仪在临床应用的可行性。方法按照行业标准推荐方法检测BS-800M和AU2700全自动生化分析仪的反应盘温度准确度与波动度、杂散光、吸光度线性、吸光度准确度、吸光度重复性、样品携带污染率、加试剂准确度和精密度、加样准确度和精密度等,并与YY/T0654-2008自动生化分析仪行业标准的性能要求进行比较。结果 BS-800M的孵育温度为(36.96±0.05)℃,略优于AU2700的(37.10±0.11)℃。BS-800M的吸光度重复性可低至0.30%,与AU2700的0.27%非常接近,均小于行业标准的1.50%。BS-800M试剂加样准确度相对偏差为0.71%~1.06%,精密度为0.86%~0.97%;AU2700分别为0.86%~1.58%与0.75%~0.91%;两者均显著优于行业标准。BS-800M的样品携带污染率仅为0.38%,与AU2700大致相当。两者的吸光度线性偏倚虽符合行业标准,但BS-800M最大为3.48%,显著高于AU2700(-1.33%)。其他试验结果均显示,BS800-M在杂散光影响、吸光度准确度、样品加注准确度与精密度等方面已达到甚至优于行业标准,与进口产品并无显著差别。结论 BS-800M与AU2700生化分析仪多方面的硬件性能均符合我国YY/T0654-2008行业标准,BS-800M生化分析仪满足临床生化检测的使用要求。     

Age‐stratified and gender‐specific reference intervals of six tumor markers panel of lung cancer: A geographic‐based multicenter study in China

BackgroundSerum biomarkers have been widely adopted in clinical practice for assisting lung cancer diagnoses, therapeutic monitoring, and prognostication. The function of a well‐performing tumor biomarker depends on a reliable reference interval (RI) with consideration of the study subjects’ age, gender, and geographical location. This study aimed to establish a RI for each of 6 lung cancer biomarkers for use in the whole country of China on Mindray platform.MethodsThe levels of serum 6 lung cancer biomarkers—namely progastrin‐releasing peptide (ProGRP), neuron‐specific enolase (NSE), squamous cell carcinoma antigen (SCC), carcinoembryonic antigen (CEA), cytokeratin‐19 fragment (CYFRA21‐1), and human epididymis protein 4 (HE4)—were measured utilizing the chemiluminescence immunoassay on the Mindray CL‐6000i platform following the laboratory standard operating procedures in apparently healthy Chinese individuals on large cohort, multicenter, and geographical consideration bases. The CLSI EP28‐A3C guideline was followed for the enrollment of study subjects.ResultsThe age‐stratified, gender‐specific RIs for ProGRP, NSE, SCC, CEA, CYFRA21‐1, and HE4 lung cancer biomarkers in the Chinese population have been established as described in the results and discussion in this work. In addition, various levels of the six lung cancer biomarkers among nine geographical locations in China have been observed.ConclusionsThe sample volume of study cohort, age, and geographical location should be considered upon establishing a reliable biomarker RI. A RI for each of six lung cancer biomarkers has been established. The results from this study would be helpful for clinical laboratories in interpreting the analytical results and for clinicians in patient management.     

Performance evaluation of the i‐Smart 300E cartridge for point‐of‐care electrolyte measurement in serum and plasma

BackgroundElectrolytes are measured regularly in a variety of clinical settings because electrolyte imbalance can be life‐threatening. Although arterial blood‐gas analysis reports electrolyte levels, the result often is discrepant with results from serum and plasma samples. Since prompt and accurate measurement of serum electrolyte levels could allow early treatment, point‐of‐care (POC) electrolyte analyzers would be beneficial. We evaluated a POC electrolyte analyzer cartridge based on the Clinical and Laboratory Standard Institute (CLSI) guidelines.MethodsPrecision and linearity were assessed according to the CLSI EP05‐A3 and EP06‐A guidelines, respectively. A comparison study was conducted with both serum and plasma samples according to the CLSI EP09‐A3. For serum, results from the i‐Smart 300E analyzer were compared with results from the Nova 8 and i‐Smart 30 analyzers. For plasma, results were compared among the i‐Smart 300E, Nova 8, i‐Smart 30, and Cobas c702 analyzers.ResultsCoefficients of variation in the precision analysis were all less than 5%. Linearity assessment demonstrated a coefficient of determination between 0.999 and 1.000 for all analytes. The comparison study showed a high Pearson''s correlation coefficient greater than 0.9 for all analytes, instruments, and specimens.ConclusionsThe i‐Smart 300E demonstrated good analytical performance. Its use could be beneficial in terms of both efficiency and clinical outcome in point‐of‐care testing (POCT) for electrolyte levels from serum and plasma samples.     

3种血细胞分析仪检测结果比对及偏差评估

目的对3种血细胞分析仪的重复性及检验结果的差异进行方法学对比和偏差评估,探讨不同型号血细胞分析仪检测结果是否具有可比性及偏差是否在允许范围内。方法以可溯源的贝克曼COULT血细胞分析仪为参比仪器,迈瑞BC-3000血细胞分析仪（BG3000）和希森美康XS-1000i血细胞分析仪（XS-1000i）为检测仪器,用新鲜抗凝全血在3种仪器上检测,对检测结果进行分析评估。结果3种仪器检测白细胞、红细胞、血红蛋白、血小板4个项目经F检验差异无统计学意义（P〉0．05）,偏差均在允许范围。结论3种仪器性能稳定,重复性佳,相关性良好,结果具有可比性,在临床中可同时或交替使用。     

Performance evaluation of leukocyte differential on the hematology analyzer Celltac G compared with two hematology analyzers,reference flow cytometry method,and two manual methods

BackgroundThe automated hematology analyzer Celltac G (Nihon Kohden) was designed to improve leukocyte differential performance. Comparison with analyzers using different leukocyte detection principles and differential leukocyte count on wedge film (Wedge‐Diff) shows its clinical utility, and comparison with immunophenotypic leukocyte differential reference method (FCM‐Ref) shows its accuracy performance.MethodsFor method comparison, 598 clinical samples and 46 healthy volunteer samples were selected. The two comparative hematology analyzers (CAAs) used were XN‐9000 (Sysmex) and CELL‐DYN Sapphire (Abbott). The FCM‐Ref provided by the Japanese Society for Laboratory Hematology was selected, and a flow cytometer Navios (Beckman‐Coulter) was used. In manual differential, two kinds of automated slide makers were used: SP‐10 (Sysmex) for wedge technique and SPINNER‐2000 (Lion‐Power) for spinner technique. The spinner technique avoids the issue of Wedge‐Diff smudge cells by removing the risk of breaking cells and non‐uniformity of blood cell distribution on films (Spinner‐Diff).ResultsThe Celltac G showed sufficient comparability (r = 0.67–1.00) with the CAAs for each leukocyte differential counting value at 0.00–40.87(10⁹/L), and sufficient comparability (r = 0.73–0.97) with FCM‐Ref for each leukocyte differential percentage at 0.4–78.5. The identification ratio of the FCM‐Ref in CD45‐positive cells was 99.7% (99.4% to 99.8%). Differences were found between FCM‐Ref/Celltac G/XN‐9000/Spinner‐Diff and Wedge‐Diff for monocytes and neutrophils. The appearance ratio of smudge cells on wedge and spinner film was 12.5% and 0.5%.ConclusionThe Celltac G hematology analyzer''s leukocyte differential showed adequate accuracy compared with the CAAs, FCM‐Ref, and two manual methods and was considered suitable for clinical use.     

Comparability of four clinical laboratory measurement methods for GGT and commutability of candidate reference materials

BackgroundThis study was conducted to evaluate the progress in the standardization of the gamma‐glutamyl transferase (GGT) to achieve metrological traceability of routine in vitro diagnosis (IVD) medical devices.MethodsWe collected 25 single fresh frozen serum samples for GGT analysis. Candidate reference materials (RMs), calibrators, internal quality controls (IQC), and external quality assessment (EQA) materials from the National Center for Clinical Laboratory (NCCL), Beijing Center for Clinical Laboratory (BCCL), and College of American Pathologists (CAP) were randomly added to these serum samples. A total of 42 samples were examined using IFCC reference method and four different IVD medical devices to perform the comparability and commutability study.ResultsThe four IVD medical devices achieved trueness assessment within the measurement range. Linear analysis showed the agreement of Siemens ADVIA 2400, Hitachi 7600‐020/BioSino, Beckman AU 5800, and Roche Cobas 501 with the reference method. These assay pairs were comparable at the medical decision levels. The GGT in‐house candidate RMs, and Beckmann and Roche calibrators were all within the limits of the 95% prediction intervals, the commutability of BioSino calibrators was indeterminate, and some internal and external quality controls were not commutable for comparisons of certain IVD medical devices vs the reference method.ConclusionsBy comparing with the reference method, we found that performance of GGT conventional measurement systems to be traceable to the higher order references was improved. The commutable materials for calibration and trueness controls of routine methods were significant to promote the standardization of GGT analysis.     

A new method for anti‐negative interference of calcium dobesilate in serum creatinine enzymatic analysis

BackgroundSerum creatinine is a widely used biomarker for evaluating renal function. Sarcosine oxidase enzymatic (SOE) analysis is currently the most widely used method for the detection of creatinine. This method was negatively interfered with by calcium dobesilate, causing pseudo‐reduced results. The aim of this study was to explore a new method to alleviate the negative interference of this drug on creatinine detection.MethodWe formulated eight drug concentrations and 12 creatinine concentrations from serum. The SOE method, the new method, and the Jaffe method were used for detection in five systems. Creatinine biases were analyzed under the conditions with or without the interference of calcium dobesilate, at consistent or inconsistent creatinine concentrations. Creatinine concentrations were also analyzed at three medical decision levels (MDLs).ResultsCalcium dobesilate had negative interference in creatinine SOE analysis. With the increase in calcium dobesilate concentrations, the negative bias increases. The new BG method showed an anti‐negative interference effect. In the Roche system, the BG method reduced the negative bias from −71.11% to −16.7%. In the Abbott system, bias was reduced from −45.15% to −2.74%. In the Beckman system, the bias was reduced from −65.36% to −7.58%. In the Siemens system, the bias was reduced from −58.62% to −7.58%. In the Mindray system, the bias was reduced from −36.29% to −6.84%.ConclusionThe new method alleviated the negative interference of calcium dobesilate in creatinine SOE detection. The negative bias could be reduced from −60% or −70% to less than −20%.     

Clinical evaluation of a laboratory‐developed test using clone E1L3N for the detection of PD‐L1 expression status in non‐small cell lung cancer

BackgroundProgrammed death ligand 1 (PD‐L1) has been used as a diagnostic marker to identify patients that will benefit from immune checkpoint inhibitors in non‐small cell lung cancer (NSCLC). Immunohistochemistry with E1L3N clone is one of the most widely used and inexpensive laboratory‐developed tests for PD‐L1, but still need to be compared and validated with standard methods for clinical application.MethodsWe investigated the performance of E1L3N clone for PD‐L1 testing in 299 tumor tissues of NSCLC patients and its comparability with FDA‐approved 22C3 clone.ResultsThe results show that the negative coincidence rate, weak positive coincidence rate, and positive coincidence rate were 97.4%, 92.2%, and 97.6% using the E1L3N assay relative to the 22C3 assay, respectively. An overall agreement of 96.3% was achieved between these two assays. We also found that the overall concordances were 97.8% and 93.9% for PD‐L1 detection in large and small specimens, respectively, and no significant difference was obtained between these two assays (p = 0.076). In addition, the expression of PD‐L1 was not detected in tumor tissues of benign lung disease using both the E1L3N and 22C3 assays.ConclusionE1L3N can be used as a reliable alternative antibody clone to evaluate PD‐L1 expression status for NSCLC patients.     

全自动血细胞分析仪检测血小板结果的可比性研究

目的比较迈瑞BC‐5300与Sysmex XT2000i全自动血细胞分析仪检测血小板结果的准确性.方法用医院门诊及住院患者清晨空腹采集肘静脉全血常规样本剩余血(EDTA‐K2抗凝)256例,分别在迈瑞 BC‐5300和Sysmex XT2000i全自动血细胞分析仪上进行血小板项目检测.结果同一份标本在血细胞分析仪检测结果比较:迈瑞BC‐5300血小板计数结果为(189.44±50.05)×109/L ,Sysmex XT2000i血小板计数结果(190.04±50.84)×109/L ,二者差异有统计学意义(P< 0.05);迈瑞 BC‐5300血小板平均体积结果为(8.10 ± 0.69)fL ,Sysmex XT2000i血小板平均体积结果为(8.12 ± 0.67)fL ,二者差异有统计学意义(P<0.05);迈瑞BC‐5300血小板分布宽度结果为15.23 ± 0.57,Sysmex XT2000i血小板分布宽度结果为15.21 ± 0.56,二者差异有统计学意义(P<0.05).结论不同的血细胞分析仪对健康人全血样本的血小板指标检测结果有重要影响.     

Dynamic observation of SARS‐CoV‐2 IgM,IgG, and neutralizing antibodies in the development of population immunity through COVID‐19 vaccination

BackgroundCurrently, mass vaccine inoculation against coronavirus disease‐2019 (COVID‐19) has been being implemented globally. Rapid and the large‐scale detection of serum neutralizing antibodies (NAbs) laid a foundation for assessing the immune response against SARS‐CoV‐2 infection and vaccine. Additional assessments include the duration of antibodies and the optimal time for a heightened immune response.MethodsThe performance of five surrogate NAbs—three chemiluminescent immunoassay (CLIA) and two enzyme‐linked immunosorbent assays (ELISAs)—and specific IgM and IgG assays were compared using COVID‐19‐vaccinated serum (n = 164). Conventional virus neutralization test (cVNT) was used as a criterion and the diagnostic agreement and correlation of the five assays were evaluated. We studied the antibody responses after the two‐dose vaccine in volunteers up to 6 months.ResultsThe sensitivity and specificity of five surrogate NAb assays ranged from 84% to 100%. Our cVNT results indicated great consistency with the surrogate assays. At 28 days after primary vaccination, the seropositivities of the NAbs, IgG, and IgM were 6%, 4%, and 13%, respectively. After the booster dose, seropositivities reached 14%, 65%, and 97%, respectively. Six months after receipt of the second dose, the NAb positive rate was eventually maintained at 66%. In all COVID‐19 convalescents, patients were detected with 100% NAb sat three months after discharge.ConclusionCOVID‐19 vaccine induced a humoral immune response lasting at least six months. Rapid serological detection was used as a proxy for identifying changes in immunity levels and as a guide to whether an individual may require a booster vaccination.     

Simultaneous point‐of‐care testing of blood lipid profile and glucose: Performance evaluation of the GCare Lipid Analyzer

BackgroundPoint‐of‐care (POC) testing provides quick results and includes tests for blood glucose and lipid profiles. We evaluated the newly developed POC device, the GCare Lipid Analyzer, which is used to measure glucose, total cholesterol (TC), triglyceride (TG), and high‐density lipoprotein cholesterol (HDL‐C) levels.MethodsVenous and capillary blood samples were collected from patients who visited Korea University Guro Hospital. The results obtained using the GCare Lipid Analyzer were compared with those obtained using the TBA 2000FR chemistry analyzer and YSI 2300 STAT Plus analyzer. The glucose system evaluation process was based on the International Organization for Standardization 15197:2013 guidelines.ResultsThe correlation coefficients (R) for TC, TG, and HDL‐C were 0.965, 0.969, and 0.943 in capillary blood and 0.969, 0.990, and 0.956 in venous blood, respectively. The total errors for TC, TG, and HDL‐C of the lipid profile using venous blood were all acceptable at 6.6%, 9.3%, and 11.6%, respectively. For glucose concentrations <100 mg/dl, 96.1% of the measured glucose levels were within ±15 mg/dl in venous samples and 100% were within ±15 mg/dl in capillary samples. For glucose concentrations ≥100 mg/dl, 100% and 99.5% of the measured glucose levels were within 15% for venous and capillary blood, respectively.ConclusionThe performance of the GCare Lipid Analyzer is acceptable for both blood glucose and lipid profile testing, indicating that it is reliable for use in patients with diabetic dyslipidemia.     

A dilute‐and‐shoot liquid chromatography–tandem mass spectrometry method for urinary 18‐hydroxycortisol quantification and its application in establishing reference intervals

BackgroundEighteen‐hydroxycortisol (18‐OHF) is a potential biomarker for differential diagnosis of the two major primary aldosteronism subtypes, aldosterone‐producing adenoma, and idiopathic hyperaldosteronism.MethodsUrine samples were processed, and the 18‐OHF in urine samples were successfully quantified by in‐house established dilute‐and‐shoot liquid chromatography–tandem mass spectrometry (LC–MS/MS) method. Separation was accomplished on a Sigma Ascentis Express C18 column with a gradient mixture of phase (A) 0.2% formic acid in water and phase (B) 0.2% formic acid in methanol at a flow rate of 0.4 ml/min. Mass spectrometric detection was performed in positive electrospray ionization mode via a mass spectrometer.ResultsThe linearity of urinary 18‐OHF ranged from 4.28 to 8.77 × 10³ nmol/L, with a lower limit of quantification at 4.28 nmol/L. The intra‐ and inter‐precision were both below 3%. The range of analytical recovery was 97.8%–109.2%. The validated dilute‐and‐shoot LC–MS/MS method was compared with the SPE LC–MS/MS method modified from the one reported in 2013. The results by Passing–Bablok regression analysis and Bland–Altman plotting demonstrated a good agreement between the two methods. The presented method was then applied to establish sex‐specific reference intervals from 62 males and 62 females, respectively. The calculated 2.5%–97.5% reference intervals for 24‐h urinary 18‐OHF were 113–703 nmol/day for males and 71.2–450 nmol/day for females.ConclusionThe presented dilute‐and‐shoot LC–MS/MS method for 18‐OHF quantification showed a good performance in the clinical application. Furthermore, the sex‐specific reference intervals for 24‐h urinary 18‐OHF were first established and quite important for its application in primary aldosteronism subtyping.     

Development,validation, and clinical application of an FIA‐MS/MS method for the quantification of lysophosphatidylcholines in dried blood spots

BackgroundLysophosphatidylcholine (LPC) plays pivotal roles in several physiological processes and their disturbances are closely associated with various disorders. In this study, we described the development and validation of a reliable and simple flow injection analysis–tandem mass spectrometry (FIA‐MS/MS)‐based method using dried blood spots (DBS) for quantification of four individual LPC (C20:0, C22:0, C24:0, and C26:0).MethodsLysophosphatidylcholines were extracted from 3.2 mm DBS with 85% methanol containing 60 ng/ml internal standard using a rapid (30 min) and simple procedure. The analytes and the internal standard were directly measured by triple quadrupole tandem mass spectrometry in multiple reactions monitoring mode via positive electrospray ionization.ResultsMethod validation results showed good linearity ranging from 50 to 2000 ng/ml for each LPC. Intra‐ and inter‐day precision and accuracy were within the acceptable limits at four quality control levels. Recovery was from 70.5% to 107.0%, and all analytes in DBS were stable under assay conditions (24 h at room temperature and 72 h in autosampler). The validated method was successfully applied to assessment of C20:0‐C26:0LPCs in 1900 Chinese neonates. C26:0‐LPC levels in this study were consistent with previously published values.ConclusionWe propose a simple FIA‐MS/MS method for analyzing C20:0‐C26:0LPCs in DBS, which can be used for first‐tier screening.     

Comparison between a new thyroglobulin assay with the well‐established Beckman Access immunoassay: A preliminary report

ObjectivesMeasurement of serum thyroglobulin (Tg) plays a key role in the post‐thyroidectomy management of differentiated thyroid carcinoma (DTC). In this context, the performance of new‐generation thyroglobulin assay has clinical implications in the follow‐up of DTC patients. Aim of this study was to compare the new highly sensitive Liaison Tg II (Tg‐L) with the well‐established Tg Access assay (Tg‐A).Materials and methodsA total of 91 residual serum samples (23 positive and 68 negatives for Tg auto‐antibodies) were tested by the Beckman Access and Diasorin Liaison assays. Study samples were from 21 patients with pathologically proven DTC and control samples from 70 (16 patients with benign thyroid disease and 54 apparently healthy subjects).ResultsOur results showed that Tg‐L was highly correlated with Tg‐A for both values ranging between 0.2 and 50 ng/mL (Pearson''s r = 0.933 [95%CI 0.894‐0.958], P < .001) and higher than 50 ng/mL (Pearson''s r = 0.849 [95%CI 0.609‐0.946], P < .001). For Tg values lower than 0.2 ng/mL, the overall concordance rate was 92%. Moreover, we tested 7 fine‐needle aspiration washout fluids (FNA), showing an overall concordance rate in discriminating negative and positive of 100%. Finally, we found no interference by Tg auto‐antibodies (TgAbs) for both Tg‐L and Tg‐A. Conversely, rheumatoid factor (RF) interferes with Tg‐A, but not with Tg‐L in one patient with no relapsing thyroid carcinoma.ConclusionsLiaison Tg II demonstrated a good correlation with Access Tg assay both for sera and FNAs. Further studies on larger population are needed to evaluate Tg‐L clinical impact on DTC patient''s follow‐up.