Practical Laboratory Medicine最新文献

Objective

The 24-h urine protein remains the gold standard to diagnose proteinuria in suspected preeclamptic patients. However, this test is time consuming and sometimes inaccurate. In this study, we aimed to analyse the correlation between the random urine protein/creatinine ratio (UPCR) and 24-h urine protein and to explore the clinical value of UPCR in the diagnosis of preeclampsia.

Method

We retrospectively evaluated 109 pregnant women from our hospital who had hypertensive diseases. They were grouped according to time of urine collection and disease severity to compare differences in random urine protein, urine creatinine, and UPCR. The correlation between the UPCR and 24-h urine protein was determined by Pearson's linear correlation.

Results

We found no statistically significant differences in random urine protein, urine creatinine, or UPCR among the four time of sampling groups. Further, random urine protein, UPCR, and 24-h urine protein between the gestational hypertension and preeclampsia groups differed significantly (P < 0.001). Correlation analysis showed significant positive correlation between random urine protein, and 24-h urine protein, and UPCR and 24-h urine protein, with r values of 0.789 and 0.810, respectively. According to the receiver operating characteristic (ROC) curve, the optimal threshold, sensitivity, specificity, and area under the curve of UPCR for the diagnosis of preeclampsia were 0.456 g/mmol, 67.8 %, 78.3 %, and 0.747, respectively (95 % confidence interval [CI], 0.65–0.844).

Conclusion

This study indicated that UPCR is significantly correlated with 24-h urine protein and is expected to replace the 24-h urine protein test as a diagnostic indicator of preeclampsia.

Background

Vitamin D (vit-D) deficiency is highly prevalent in the Korean population, highlighting the need for accurate measurements. In this study, the interferences by endogenous and cross-reactive substances were compared between routine vit-D immunoassays and mass spectrometry (MS) methods.

Methods

Two MS methods and 4 immunoassays from different manufacturers (Abbott, Beckman Coulter, Roche, Siemens) were compared. Residual samples that were icteric, lipemic, hemolyzed, high in rheumatoid factor, from myeloma patients, or patients undergoing hemodialysis were collected. Also, 4 levels of National Institute of Standards and Technology (NIST) Standard Reference Material 972a, and 12 samples serially spiked with 3-epi-25-OH-D₃ were prepared.

Results

Significant interferences were observed in hemolytic (Roche), icteric (Beckman and Siemens) and lipemic samples (all 4 immunoassays). Level 4 NIST material and 3-epi-25-OH-D₃-spiked samples induced significant cross-reactivity, yielding higher total vit-D measurements in non-epimer-separating MS methods, and both the Beckman and Roche immunoassays.

Conclusion

Most observed interferences were consistent with manufacturers’ claims, but overall improvement of immunoassay bias limits is required. Awareness of potential interference is important to increase the accuracy of vit-D measurements. Moreover, care is due when interpreting vit-D results of newborns, infants and less commonly, pregnant women, who are known to have physiologically high levels of the highly cross-reactive 3-epi-25-OH-D₃.

C-reactive protein (CRP) is an established acute-phase marker for infection, inflammation and tissue injury, used to guide clinical decision-making in primary and secondary care. This study compared the analytical performance of the quantitative microfluidic point-of-care LumiraDx CRP Test to a laboratory-based reference method (Siemens RCRP Flex assay on the Dimension® Xpand®) and evaluated equivalence of sample matrices (blood versus plasma) in point-of-care settings using samples from patients presenting with symptoms of infection or inflammation. The LumiraDx CRP Test demonstrated close agreement with the lab reference test (range, 5.1 to 245.2 mg/L, r = 0.992, slope = 0.998, intercept = –0.476; n = 205) and notable agreement between fingerstick and venous blood and plasma (r = 0.974–0.983; n = 44). Paired replicate precision had mean coefficients of variation of 6.4 % (plasma), 6.6 % (capillary direct) and 8.1 % (venous blood); overall error rates were 2.9 %. The quantitative LumiraDx CRP Test showed robust analytical performance across sample matrices and close agreement compared to the laboratory reference method when used at the point of care.

Objectives

High-performance liquid chromatography (HPLC) is commonly used to measure hemoglobin A_1c (HbA_1c) levels and detect hemoglobin variants (Hb-Vars). HLC-723GR01 (GR01) is a new-generation automated ion-exchange HPLC system with two switchable analysis modes, namely short (30 s/test) and long modes (50 s/test). We evaluated the general performance of both analysis modes of GR01 for quantifying HbA_1c and detecting Hb-Vars.

Design and methods

We evaluated the instrument's precision based on CLSI protocol EP-05-A3. A comparison of the two analysis modes of GR01 against the standard mode of HLC-723G11 was performed on 100 whole blood samples. The GR01 long mode was compared with affinity HPLC (AF-HPLC) for detecting common Hb-Vars (HbE, HbD, HbS, and HbC, >20 samples). To examine the detection capability for minor Hb-Vars, we analyzed 26 Hb-Vars using multiple analyzers, including both analysis modes of GR01.

Results

Both modes of GR01 had within-laboratory coefficients of variation of ≤1.0 % from four samples with HbA_1c concentrations of 32–86 mmol/mol. Good correlation was observed between GR01 and HLC-723G11. The results for HbA_1c detection in the presence of the major variants revealed a strong correlation between the long mode of GR01 and AF-HPLC (r = 0.986–0.998), and the difference biases ranged 0.1–1.9 mmol/mol. In the long mode, only one variant had a difference bias exceeding 14 % [10 % (%NGSP)].

Conclusion

The two analysis modes of GR01 were fast and had high accuracy and reproducibility, indicating their utility for routine clinical use in measuring HbA_1c samples with Hb-Vars.

Objectives

Human chorionic gonadotropin (hCG) levels are essential for the management of trophoblastic diseases. This study aimed to compare the sensitivities and relationships of two hCG measurement methods (total hCG and the free β-subunit of hCG) in managing gestational trophoblastic disease (GTD).

Design and Methods

We analyzed data from patients treated for GTD at Chiba University Hospital between 2008 and 2019. We focused on cases where both total hCG (mIU/mL) and the free β-subunit of hCG (ng/mL) were measured on the same day.

Results

Out of 80 patients (mean age 38.9 ± 11.7 years) and 158 measurements, 26 had values below the sensitivity threshold for both tests. Fifty-nine measurements were positive for total hCG but below the sensitivity threshold for the free β-subunit of hCG, whereas only two showed the opposite. Seventy-one measurements were positive for both total hCG and the free β-subunit of hCG. There was a significant correlation between total hCG and the free β-subunit of hCG with both positive values, (r = 0.94, p < 0.001; Spearman's correlation test). Of the 85 measurements with undetectable free β-subunit levels, 26 also had undetectable total hCG levels. However, total hCG was detectable in 59 patients from these cases, with a median value (interquartile range) of 2.9 (1.75–4.9) mIU/mL.

Conclusions

In the management of GTD, the use of the free β-subunit system alone cannot be recommended.

Objective

Nucleic acid testing can accurately and rapidly identify the presence of pathogenic bacteria. In this study, we analyzed respiratory pathogenic bacteria nucleic acids by LAMP (Loop-mediated isothermal amplification) to clarify the clinical application in patients with bacterial pulmonary infections.

Methods

Clinical data and specimens were collected from 99 patients with bacterial pulmonary infections from June 2021 to April 2023. We compared the differences between nucleic acid detection of LAMP and sputum culture. The correlation between inflammation manifestations of pulmonary imaging and the nucleic acid detection of LAMP was compared and analyzed. And the relationship between LAMP and blood inflammatory markers were analyzed.

Results

The positive rate of LAMP using sputum specimens was significantly higher than that of sputum culture (P < 0.05). Pathogenic bacteria in sputum samples are more likely to be detected by LAMP in patients with inflammatory on lung imaging examination. The coincidence rate of elevated PCT and CRP expression with positive LAMP results were 83.87 % and 88.71 %, respectively. Moreover, PCT, CRP and WBC were significantly higher in LAMP positive group than those in negative group (P < 0.05).

Conclusion

Nucleic acid testing of sputum specimens for pathogenic bacteria by LAMP on the basis of imaging examination can provide a rapid and accurate experimental basis for clinical diagnosis of bacterial pulmonary infections.

Background and aims

Protein C is a plasma protein, and its active form regulates blood coagulation. The recommended unit of protein C activity is IU/mL; however, some laboratories use percentage. Some deficiencies cannot be detected owing to measurement principles. This study sought to quantify protein C activity levels and overcome the limitations of the current measurements.

Materials and methods

Our protein C activity measurement method mimicked the blood coagulation cascade and used a thrombin-specific chromogenic reagent. The control was prepared by adding protein C to the protein C deficient plasma. The calibration curve was plotted as the increase in the absorbance per minute and the concentration of protein C in the control. Statistical tests were performed to compare our method with the current chromogenic method.

Results

A calibration curve was constructed (y = −0.0132x + 0.14, R² = 0.9987, n = 10). The statistical results of our method suggested non-inferiority when compared to the current chromogenic method (α = 0.05).

Conclusion

The quantitative measurement was performed using plasma samples. Our method provides the possibility of expressing protein C activity quantitatively and detecting deficiencies that cannot be detected using the current chromogenic method.

Objectives

In this study, we aimed to establish the trimester-specific RIs of renal function tests (RFTs) in singleton pregnant women and investigate the associations between adverse perinatal outcomes and abnormal renal function laboratory results.

Methods

The results of RFTs and the associated medical records were retrieved from 16489 singleton pregnant women who underwent first- and third-trimester prenatal screening and gave a live birth at out institute between August 2018 and December 2019. The RFTs were performed on the automated immunochemistry platform ARCHITECT ci16200 (Abbott Laboratories Ltd, Abbott Park, Illinois, US) in the clinical laboratory of our institute. The nonparametric 2.5th-97.5th percentile intervals and the indirect Hoffmann methods were used to define the trimester-specific RIs. The associations between abnormal RFTs and adverse pregnancy outcomes was assessed statistically by logistic regression.

Results

There was no significant difference between the direct observational and the indirect Hoffmann methods in establishing RIs of RFTs. Compared with RFTs in the first trimester, the concentrations of serum BUN and Crea were slightly decreased (p < 0.001), and the serum UA and Cys C levels were significantly elevated in the third trimester (p < 0.001). In the logistic regression analysis, high concentrations of UA, Crea, and Cys C in late pregnancy were associated with an increased risk of postpartum hemorrhage. Meanwhile, early pregnancy UA was associated with a modestly increased risk of GDM, GH, and PE.

Conclusion

It is necessary to establish trimester-specific RIs for RFTs, in order to appropriately interpret laboratory results and to identify women with high risks of developing various adverse outcomes.

Objective

To evaluate the performance of newly developed glycated hemoglobin (HbA1c) clinical analytic reagents and HPLC columns, applied on Tosoh HLC-723 G8 Analyzer.

Methods

Newly developed reagents and columns were used on a Tosoh HLC-723 G8 Analyzer (standard mode) system to measure both of qulity contorls and the clinical blood samples to evaluate the performances of these newly developed prodcuts including precision, accuracy, linearity, carryover, bias evaluation, correlation with commercial reagents, and stability according to CLSI recommendations.

Results

The CV of intra-assay precision and inter-assay precision of quality control and clinical blood sample assays using Lirimax products were both less than 3.00%. And the REs of accuracy were less than 6.00%. Linearity: R² = 0.9993 in the concentration range 4.77%–14.67%. Carryover: 0.05%. The Bland-Altman mean difference: −0.003583% HbA1c (CI: 0.07398: −0.08115); Passing-Bablok regression: y = 1.0022(0.9984:1.006)x-0.01097(-0.03776: 0.01582), R² = 0.9996. Stability evaluation was also acceptable.

Conclusion

The performance of newly developed products was well evaluated for HbA1c measurement on a TOSOH G8 Analyzer which shows excellent suitability for clinical assay.

Extracorporeal photopheresis is an established procedure for refractory graft-versus-host disease, a major complication associated with notable morbidity and mortality in patients with allogeneic hematopoietic stem cell transplant. Despite being implemented over a decade ago, there is scant information about potential interactions or analytical interferences with concomitant drugs in this polymedicated population. Here we report the case of a pediatric patient diagnosed with cutaneous steroid-refractory acute graft-versus-host disease after unrelated allogeneic hematopoietic stem cell transplant that was treated with photopheresis. Analytical quantification of voriconazole by HPLC-PDA the day following photopheresis treatment did not permit therapeutic drug monitoring (TDM) due to the presence of interference at the voriconazole retention time. Following investigations, it was demonstrated that the interference is likely attributable to a psoralen-based compound. The interference was not present when samples were obtained prior to photopheresis, enabling TDM. This case underscores the relevance of communication among the members of the treating team to perform reliable TDM, especially in routine clinical practice of pediatric patients with complex diseases undergoing innovative treatments. This finding is relevant to voriconazole quantification by HPLC-PDA, frequently used in laboratories based in middle-income countries.