Journal of Applied Laboratory Medicine最新文献

Background: Gout and calcium pyrophosphate deposition (CPPD) disease are common crystalline arthropathies. Identification of crystals in synovial fluid using polarized light microscopy (PLM) aids diagnosis. In routine clinical practice, the volume of synovial fluid available for PLM is frequently insufficient, especially when fluid is also needed for other analyses, such as Gram stain and culture. Few studies have investigated the reliability of microscopic examination for crystals, with or without polarization, using Gram-stained synovial fluid specimens. This study estimated the sensitivity and specificity of microscopy with and without polarization on Gram-stained specimens for identification of crystals compared with standard PLM on unstained samples.

Methods: In total, 105 unstained synovial and bursal fluid samples were processed and examined by laboratory personnel using routine PLM procedures. Gram-stained samples of the same fluid were independently interpreted by microbiologists trained in examining fluid for crystals using standard light microscopy, followed by at least 2 pathologists using PLM.

Results: Compared with standard PLM on unstained samples, the sensitivity and specificity of crystal examination by microbiologists on Gram-stained samples were 16% and 98%, respectively. Pathologists, using PLM on these Gram-stained samples, achieved slightly better sensitivity (24.5% and 96%, respectively). Concordance regarding crystal type was 100% and unaffected by Gram stain.

Conclusions: Crystal examination of Gram-stained synovial and bursal fluid by trained personnel has low sensitivity but high specificity compared with standard evaluation of unstained samples. Examination of Gram-stained samples with PLM may be helpful when sample volumes are limited and, when positive, has sufficient specificity to support crystalline arthropathy diagnoses.

Background: Xylazine, a veterinary sedative, is increasingly being discovered in the illegal drug supply across the United States and is associated with overdose fatalities. Not approved for human use, xylazine poses life-threatening risks, particularly when used in conjunction with opioids such as fentanyl. This study evaluates the prevalence of xylazine in urine samples that screened positive for fentanyl. The evaluation involved measuring the parent drug xylazine and its metabolites, xylazine glucuronide and hydroxy-xylazine, as well as finding their correlation with fentanyl and norfentanyl concentrations in patient samples.

Methods: Samples were collected over a one-month period. Urine samples were analyzed for fentanyl, norfentanyl, and 3 xylazine-specific analytes (i.e., xylazine, xylazine glucuronide, and hydroxy-xylazine). Briefly, reverse-phase chromatographic separation was performed on a Bonshell Phenyl-Hexyl column utilizing a binary mobile phase gradient. The eluents were detected through positive electrospray ionization and multiple reaction monitoring analysis on a triple quadrupole mass spectrometer.

Results: Out of a total of 230 urine samples, 184 were confirmed positive for fentanyl. Xylazine was detected in 56 out of the 184 fentanyl-positive samples, accounting for 30% of the fentanyl-positive confirmatory test. Xylazine (or its metabolites) was not observed in fentanyl-negative samples. Furthermore, the parent xylazine drug was detected in all 56 samples, whereas the metabolite glucuronide and hydroxy forms were only detected in 28 and 6 samples, respectively.

Conclusions: This study estimated a xylazine prevalence of 30% in fentanyl-positive urine samples within our local Western New York population. This study represents the first report within our clinical population.

Background: Immunoassay drug screens provide rapid analysis of urine for the presence of therapeutics and drugs of abuse. Compared to definitive (confirmatory) methods, immunoassays are prone to false-positive and -negative results. Laboratories generally rely on manufacturers' claims regarding method sensitivity and specificity; few have the resources to independently verify performance. In this study, we review the performance of our opioid immunoassay drug screens in comparison to a definitive method.

Methods: Results of 859 urine samples tested via opioid immunoassay screens for buprenorphine, fentanyl, methadone metabolite (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine; EDDP), opiates, and oxycodone were compared to definitive results obtained via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The data examined here included multiple samples from individual patients. Our quantitative LC-MS/MS method includes 19 opioid compounds (parent drugs plus metabolites).

Results: Immunoassay sensitivity and specificity ranged from 96% to 100% and 84% to 99%, respectively. The sensitivity and specificity of these screens were similar to manufacturers' claims with some exceptions. The opiates immunoassay had poor performance when limiting the comparison to its target compound, morphine, but improved when including all compounds listed in the manufacturer's instructions for use (IFU). While demonstrating good sensitivity, the buprenorphine immunoassay demonstrated lower specificity than stated in the IFU.

Conclusions: The opioid immunoassay screens in use at our facility compared favorably to a definitive LC-MS/MS method. The urine fentanyl screen had the lowest sensitivity (96%) and had a specificity of 97%. The urine buprenorphine assay was the least specific (84%) and had a sensitivity of 99%.

Background: Therapeutic drug monitoring of the immunosuppressant tacrolimus is commonly performed by immunoassay or LC-MS/MS. Measurement biases between these methodologies have been characterized for immediate-release tacrolimus (IR-tac; Prograf) but have not been performed for extended-release formulations such as Envarsus. These discrepancies can impact patient care, as appropriate dosing is required to maintain therapeutic concentrations and immunosuppression.

Methods: Validation of a whole-blood LC-MS/MS method for the simultaneous quantification of tacrolimus and its major metabolite, desmethyl tacrolimus, was performed using traceable calibrators (tacrolimus, ERM-DA110a) and quality control (QC) material for tacrolimus and standard material for desmethyl tacrolimus. Tacrolimus concentrations were determined by LC-MS/MS and the ARCHITECT immunoassay in patients receiving either IR-tac or Envarsus for clinical care.

Results: External calibration curves for both tacrolimus and desmethyl tacrolimus were linear (R2 > 0.995), and the analytical measurement range (AMR) for tacrolimus spanned from 1.1 to 31.6 ng/mL. Calibrator/QC biases were within 15% of their spiked concentrations throughout the AMR, and within-run imprecision was <10%, except at the lower limit of quantification (n = 25). Between-run imprecision for low, mid, and high QC levels was ≤11% over a 2-week period (n = 5 days). Comparative biases between immunoassay and LC-MS/MS were significantly lower (P = 0.0074) for patients receiving Envarsus (n = 20 specimens) relative to patients receiving IR-tac (n = 32 specimens).

Conclusions: Biases between immunoassay and LC-MS/MS tacrolimus measurements in patients receiving immediate-release vs extended-release formulations indicate that their distinct pharmacokinetic profiles impact measurement accuracy. These assay biases should be considered when interpreting tacrolimus concentration measurements.

Background: Hyperaldosteronism involves complex, multidisciplinary management, including clinical testing, radiological exams, and adrenal venous sampling (AVS). This study assesses AVS outcomes at a large referral center, focusing on cannulation success, lateralization of aldosterone-producing adenomas, and correlation with radiological and surgical findings.

Methods: A retrospective review of 153 patients who underwent AVS from September 2016 to January 2024 was conducted. Data included aldosterone and cortisol levels, procedural details, and outcomes. AVS success was determined by aldosterone-to-cortisol ratios and cortisol levels confirming adequate cannulation.

Results: Of the 153 patients, 49.9% had lateralized adenomas (51.3% left, 48.7% right), while 39.9% had bilateral adrenal hyperplasia. In 10.8% of cases, AVS was inconclusive or unsuccessful. Right adrenal vein cannulation required more attempts due to anatomical challenges. Aldosterone levels were higher in right adrenal adenomas compared to left, though cortisol levels did not predict laterality or hyperplasia. There was strong concordance between AVS, radiological, and surgical findings, except for bilateral hyperplasia cases.

Conclusions: This large series highlights AVS's central role in diagnosing hyperaldosteronism, with significant insights into cannulation challenges and biochemical correlations. The study underscores the importance of a multidisciplinary approach for accurate diagnosis and effective management.

Background: The most frequently ordered laboratory test worldwide is the complete blood count (CBC). As clinical chemists are increasingly assigned to assist or direct laboratories outside of the traditional clinical chemistry sections, such as the automated hematology section, expertise must be established. This review article is a dedication to that ongoing effort.

Content: In this primer, the white blood cell (WBC) test components of the CBC are introduced, followed by a discussion of the laboratory evaluation of leukopenia and leukocytosis.

Summary: The laboratorian's approach to consult cases should be guided by the patient's clinical history and presentation while being able to provide key laboratory-based insights to assist in resolving result discrepancies that may otherwise go unnoticed.

Background: Laboratory medicine has and continues to undergo significant transformation. This paper reviews top trends associated with laboratory medicine using insights, evidence, and outcomes derived from the UNIVANTS of Healthcare ExcellenceTM award program.

Methods: Seventy-two judge-approved best practices of measurably better healthcare were assessed for trends and insights related to outcomes and opportunities for highlighting the value of laboratory medicine.

Results: Ten industry-relevant and insightful takeaways are identified that span stakeholders and key performance indicators.

Conclusion: With evidence that spans 5 years, the findings not only substantiate the critical value of laboratory medicine, but reveal trends associated with award-winning teams, proven integrated clinical care initiatives, and the measurement of their associated outcomes.

Background: Blood-based biomarkers, especially P-tau217, have been gaining interest as diagnostic tools to measure Alzheimer disease (AD) pathology.

Methods: We developed a plasma P-tau217 chemiluminescent immunoassay using 4G10E2 and IBA493 as antibodies, a synthetic tau peptide as calibrator, and the Quanterix SP-X imager. Analytical validation performed in a College of American Pathologists-accredited CLIA laboratory involved multiple kit lots, operators, timepoints, and imagers. Florbetapir positron emission tomography was used to quantify amyloid for clinical validation.

Results: Precision across 80 runs was ≤20% CV using 23 patient-derived samples ranging from 0.09 U/mL to 3.35 U/mL. No significant lot-to-lot differences were observed. There was no interference from purified tau (2N4R) or lipemia, but hemolysis greater than 2 + was not acceptable. Functional analytical sensitivity (lower limit of quantitation) was 0.08 U/mL. Linearity studies support the use of a standard 1:2 plasma dilution. Samples demonstrated stability at 7 freeze/thaw cycles, with room temperature and refrigerated stability established for up to 72 hours. The final analytical measurement range was 0.08 to 2.81 U/mL. The calibration curve maintained ≤20% CV for raw signal intensity and 80% to 120% relative error for back-fitted concentration using a log-log power regression. Initial clinical assessment using plasma samples from 1091 individuals screened in TRAILBLAZER-ALZ 2 demonstrated an area under the curve of 91.6% (95% CI 0.90-0.94) with brain amyloid as the comparator. Positive and negative predictive value was >90% and >85%, respectively.

Conclusions: Through analytical validation, this assay demonstrated robust performance across multiple lots, operators, and instruments and could be used as a tool for diagnosing AD.

Background: Global metabolic dysfunction-associated steatotic liver disease (MASLD) prevalence is estimated at 30% and projected to reach 55.7% by 2040. In the Veterans Affairs (VA) healthcare system, an estimated 1.8 million veterans have metabolic dysfunction-associated steatohepatitis (MASH).

Methods: Adult patients at risk for MASLD in a VA healthcare system underwent Fibrosis-4 (FIB-4) and Enhanced Liver Fibrosis (ELF®) testing. Referral rates and cost savings were compared among 6 noninvasive testing (NIT) strategies using these 2 tests independently or sequentially at various cutoffs.

Results: Enrolled patients (N = 254) had a mean age of 65.3 ± 9.3 years and mean body mass index (BMI) of 31.7 ± 6, 87.4% male: 78.3% were non-Hispanic/Latino, and 96.5% had type 2 diabetes mellitus (T2DM). Among the 6 evaluated strategies, using FIB-4 followed by ELF at a 9.8 cutoff yielded the highest proportion of patients retained in primary care without need of referral to hepatology clinic (165/227; 72.7%), and was associated with the lowest costs ($407.62). Compared to the FIB-4 only strategy, FIB-4/ELF with a 9.8 cutoff strategy resulted in 26% fewer referrals and 8.47% lower costs. In the subgroup of patients with BMI >32, there were 25.17% fewer referrals and costs were 8.31% lower.

Conclusions: Our study suggests that sequential use of ELF with a 9.8 cutoff following indeterminate FIB-4 tests results in lower referral rates and lower care costs in a veteran population at risk of MASLD. Adding ELF as a sequential test after indeterminate FIB-4 might help reduce the number of referrals and overall cost of care.