Body fluid analysis: Clinical utility and applicability of published studies to guide interpretation of today’s laboratory testing in serous fluids

Opportunities and Drawbacks of Digitalized Morphologic Analysis of Body Fluids

Body fluid analysis has become a critical component of diagnostic and clinical decision-making for a wide spectrum of human pathologies. An automated microscope, a high-quality digital camera, and a software designed to identify and automatically preclassify cells and other features in stained smears comprise the most recent generation of digital morphologic analyzers. The time necessary for expert operator reclassification is another aspect that must be considered at this stage of development, because identifying and sorting distinct elements in body fluids still necessitates the involvement of an expert morphologist.

Laboratory investigation of peritoneal fluids: an updated practical approach based on the available evidence

Even though analysis of peritoneal fluids (PF) is often requested to medical laboratories for biochemical and morphological tests, there is still no mutual agreement on what the most appropriate way is to manage PF samples and which tests should be appropriately executed. In this update, we tried to identify the most useful tests for PF analysis to establish best practice indications. We performed a literature review and examined available guidelines to select the most appropriate tests by an evidence-based approach. Accordingly, the basic PF profile should include (1) serum to effusion albumin gradient and (2) automated cell counts with differential analysis. This profile allows to determine the PF nature, differentiating between 'high-albumin gradient' and 'low-albumin gradient' effusions, which helps to identify the pathophysiological process causing the ascites formation. Restricted to specific clinical situations, additional tests can be requested as follows: PF lactate dehydrogenase (LDH) and glucose, to exclude (LDH) or confirm (glucose) secondary bacterial peritonitis; PF total protein, to differentiate ascites of cardiac origin from other causes; PF (pancreatic) amylase, for the identification of pancreatic ascites; PF bilirubin, when a choleperitoneum is suspected; PF triglycerides, in differentiating chylous from pseudochylous ascites and PF creatinine, to detect intraperitoneal urinary leakage.

The laboratory investigation of pleural fluids: An update based on the available evidence

Selecting appropriate laboratory tests based on available evidence is central to improve clinical effectiveness and impacting on patient outcome. Although long studied, there is no mutual agreement upon pleural fluid (PF) management in the laboratory context. Given the experienced confusion about the real contribution of laboratory investigations to guide clinical interpretation, in this update, we tried to identify useful tests for the PF analysis, aiming to unravel critical points and to define a common line in requesting modalities and practical management. We performed a careful literature review and a deepened study on available guidelines to finalize an evidence-based test selection, intended for clinicians' use to streamline PF management. The following tests depicted the basic PF profile routinely needed: (1) abbreviated Light's criteria (PF/serum total protein ratio and PF/serum lactate dehydrogenase ratio) and (2) cell count with differential analysis of haematological cells. This profile fulfils the primary goal to determine the PF nature and discriminate between exudative and transudative effusions. In specific circumstances, clinicians may consider additional tests as follows: the albumin serum to PF gradient, which reduces exudate misclassification rate by Light's criteria in patients with cardiac failure assuming diuretics; PF triglycerides, in differentiating chylothorax from pseudochylothorax; PF glucose, for identification of parapneumonic effusions and other causes of effusion, such as rheumatoid arthritis and malignancy; PF pH, in suspected infectious pleuritis and to give indications for pleural drainage; and PF adenosine deaminase, for a rapid detection of tuberculous effusion.

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

Comparison of Five Common Analyzers in the Measurement of Chemistry Analytes in an Authentic Cohort of Body Fluid Specimens

OBJECTIVES

Interpretation of body fluid (BF) results is based on published studies and clinical guidelines. The aim of this study is to determine whether the assays from five common commercial vendors produce similar results in BFs for 12 analytes in a BF cohort.

METHODS

BFs (n = 25) and serum (n = 5) were analyzed on five instruments (Roche cobas c501, Ortho 5600, Beckman AU5800 and DXI800, Siemens Vista 1500, and Abbott Architect c8000) to measure albumin, amylase, total bilirubin, cholesterol, creatinine, glucose, lactate dehydrogenase (LDH), lipase, total protein, triglycerides, urea nitrogen, and carcinoembryonic antigen. Deming regression and Bland-Altman analysis were used for method comparison to Roche.

RESULTS

Results were significantly different from Roche for LDH and lipase on Ortho and lipase on Siemens but similar for both BFs and serum. BF differences were larger than serum differences when measuring creatinine, glucose, and urea nitrogen on Ortho and glucose on Siemens.

CONCLUSIONS

Five instruments used to perform BF testing produce results that are not significantly different except for lipase and LDH measurements. Bias of similar magnitude observed in both BF and serum should not affect interpretation. Further investigations into Ortho and Siemens measuring glucose and Ortho measuring creatinine and urea nitrogen are warranted.

A review of surface-enhanced Raman spectroscopy in pathological processes

With the continuous growth of the human population and new challenges in the quality of life, it is more important than ever to diagnose diseases and pathologies with high accuracy, sensitivity and in different scenarios from medical implants to the operation room. Although conventional methods of diagnosis revolutionized healthcare, alternative analytical methods are making their way out of academic labs into clinics. In this regard, surface-enhanced Raman spectroscopy (SERS) developed immensely with its capability to achieve single-molecule sensitivity and high-specificity in the last two decades, and now it is well on its way to join the arsenal of physicians. This review discusses how SERS is becoming an essential tool for the clinical investigation of pathologies including inflammation, infections, necrosis/apoptosis, hypoxia, and tumors. We critically discuss the strategies reported so far in nanoparticle assembly, functionalization, non-metallic substrates, colloidal solutions and how these techniques improve SERS characteristics during pathology diagnoses like sensitivity, selectivity, and detection limit. Moreover, it is crucial to introduce the most recent developments and future perspectives of SERS as a biomedical analytical method. We finally discuss the challenges that remain as bottlenecks for a routine SERS implementation in the medical room from in vitro to in vivo applications. The review showcases the adaptability and versatility of SERS to resolve pathological processes by covering various experimental and analytical methods and the specific spectral features and analysis results achieved by these methods.

Effect of pH on the Quantification of Common Chemistry Analytes in Body Fluid Specimens Using the Roche cobas Analyzer for Clinical Diagnostic Testing

OBJECTIVES

To determine the influence of pH on recovery of analytes in body fluids (BFs), investigate the mechanism of pH interference, measure the frequency of abnormal-pH BFs received, and compare pH measured by meter and paper.

METHODS

We performed pH titration in residual BFs. A low-pH BF was spiked and neutralized to investigate pH interference. We measured analytes on a Roche cobas c501 analyzer (Roche Diagnostics) and calculated the percent recovery. Measurement of pH using a meter and paper was conducted on 122 BF samples received in the laboratory.

RESULTS

Enzyme activity in BFs was unaffected when pH = 7.4-8.5 lactate dehydrogenase, pH = 7.3-10.2 amylase, pH = 6.0-9.9 lipase, and pH = 1.3-11.7 all other analytes. BFs had mean (range) pH of 8.0 (5.1-8.9), with a mean (range) difference (paper ‒ meter) of ‒0.4 (‒0.6 to 1.1).

CONCLUSIONS

Irreversible loss of enzyme activity occurs in BFs at low pH. Few clinical BFs have pH < 7.0, but laboratories should incorporate pH measurement in BF workflows.

Body fluid matrix effect evaluation on the Hitachi Labospect 008 system

BACKGROUND

Non-standard body fluids (NSBFs) can provide essential clinical information otherwise unobtainable with conventional biological specimens. However, as most commercial chemistry reagents are only validated for serum, plasma, and urine by manufacturers, individual laboratories have to validate testing with NSBF to comply with regulatory standards. However, the heightened level of oversight and uncertainty of validation requirements to comply with regulatory standards pose a significant challenge for NSBF testing in clinical laboratories.

METHODS

28 combinations of high-volume chemistry tests requested on NSBF with established clinical utility were selected from retrospective data analysis. Specimens were analyzed with both closed and open channel chemistry reagents on a LABOSPECT 008AS platform (Hitachi High-Tech Co., Tokyo, Japan). Recovery studies were performed using a high concentration serum sample and 5 clinical NSBF samples at varying concentrations for each analyte. Acceptable performance limits were defined as 100 ± 10% of expected recovery.

RESULTS

The average percent recovery ranged from 94.5% to 106.6% depending on the analyte/NSBF combination evaluated, and for each of the 28 combinations, the average percent recovery was within the predefined acceptable limits of ± 10%.

CONCLUSIONS

The recovery results from this study on the LABOSPECT 008AS platform demonstrates that any systematic matrix interference of high-volume chemistry testing on NSBF samples is well within the defined limits of acceptability. This work also demonstrates recovery studies performed by an individual laboratory are practial and it is feasible to demonstrate compliance with regulatory requirements for accuracy of chemistry testing on NSBF samples.

Pretreatment of Body Fluid Specimens Using Hyaluronidase and Ultracentrifugation

OBJECTIVE

Viscous body fluids present challenges during clinical laboratory testing. The present study was conducted to evaluate the effectiveness of hyaluronidase (HYAL) and ultracentrifugation (UC) pretreatment for a variety of body fluids before clinical chemistry testing.

METHODS

The following body fluids were evaluated: biliary/hepatic, cerebrospinal, dialysate, drain, pancreatic, pericardial, peritoneal/ascites, pleural, synovial, and vitreous. Analytes assessed included amylase, total bilirubin, cancer antigen 19-9, carcinoembryonic antigen, cholesterol, chloride, creatinine, glucose, lactate dehydrogenase, lipase, potassium, rheumatoid factor, sodium, total protein, triglycerides, urea nitrogen, and uric acid.

RESULTS

Observed percentage differences between HYAL treated and untreated fluids were less than ±15% for all analytes investigated, with a small number showing statistical significance (P <.05). In addition, UC showed increased variability for limited body fluid/analyte combinations.

CONCLUSION

The HYAL treatment effectively reduced viscosity for body fluids. Validation of specimen pretreatment processes ensures acceptable analytical performance and the absence of unanticipated interferences.

Long-term stability of clinically relevant chemistry analytes in pleural and peritoneal fluid

Introduction

Our aim was to investigate the stability of clinically relevant analytes in pleural and peritoneal fluids stored in variable time periods and variable storage temperatures prior to analysis.

Materials and methods

Baseline total proteins (TP), albumin (ALB), lactate dehydrogenase (LD), cholesterol (CHOL), triglycerides (TRIG), creatinine (CREA), urea, glucose and amylase (AMY) were measured using standard methods in residual samples from 29 pleural and 12 peritoneal fluids referred to our laboratory. Aliquots were stored for 6 hours at room temperature (RT); 3, 7, 14 and 30 days at - 20°C. At the end of each storage period, all analytes were re-measured. Deviations were calculated and compared to stability limits (SL).

Results

Pleural fluid TP and CHOL did not differ in the observed storage periods (P = 0.265 and P = 0.170, respectively). Statistically significant differences were found for ALB, LD, TRIG, CREA, urea, glucose and AMY. Peritoneal fluid TP, ALB, TRIG, urea and AMY were not statistically different after storage, contrary to LD, CHOL, CREA and glucose. Deviations for TP, ALB, CHOL, TRIG, CREA, urea and AMY in all storage periods tested for both serous fluids were within the SL. Deviations exceeding SL were observed for LD and glucose when stored for 3 and 7 days at - 20°C, respectively.

Conclusions

TP, ALB, CHOL, TRIG, CREA, urea and AMY are stable in serous samples stored up to 6 hours at RT and/or 30 days at - 20°C. Glucose is stable up to 6 hours at RT and 3 days at - 20°C. The stability of LD in is limited to 6 hours at RT.

Data on interference indices in body fluid specimens submitted for clinical laboratory analysis

Clinical chemistry analysis of body fluids from non-blood or urine sources presents a technical challenge for clinical laboratories. Examples of body fluids include biliary secretions, cerebrospinal fluid, cyst contents, dialysate, gastric aspirates, peritoneal fluid, pleural fluid, stool, surgical drain fluid, synovial fluid, and wound exudates. The heterogeneous nature of these body fluids presents technical difficulties for analysis. For example, body fluid specimens may have presence of hemolysis, icterus, or lipemia (‘interference indices’) that can interfere with clinical chemistry analysis. In the related research article, we analyzed the distribution of these interference indices and body fluid samples submitted for analysis at an academic medical center central clinical laboratory and compared this to data from serum/plasma specimens. The data in this article provide the body fluid type, clinical chemistry testing ordered, interference indices, and whether the indices exceeded the manufacturer's recommendations in the package insert for serum/blood specimens. The analyzed data are provided in the supplementary tables included in this article. The dataset reported is related to the research article entitled “Review of interference indices in body fluids specimens admitted for clinical chemistry analyses” [1].

Review of interference indices in body fluid specimens submitted for clinical chemistry analyses

Objectives

The aims of this study were to retrospectively investigate interference indices in a wide range of body fluid specimens and compare these indices to those found in serum/plasma.

Design and Methods

This retrospective study evaluated interference indices for hemolysis, icterus, and lipemia in 2752 body fluid specimens submitted for clinical chemistry testing.

Results

The distribution of interference indices for body fluid samples was generally similar to that of serum/plasma interference indices. Hemolysis of specimens submitted for lactate dehydrogenase (LD) represented the most common interference for body fluid chemistries. Body fluids collected from postsurgical drain sites had a higher proportion of tests exceeding both icterus and lipemic limits compared to serum/plasma specimens.

Conclusions

Overall, degrees of hemolysis, icterus, and lipemia observed in body fluid specimens were in large part similar to serum/plasma specimens, with a few notable differences. Body fluids exhibited a higher proportion of samples with severe icterus or lipemia. Severely lipemic body fluid samples were significantly less likely to also be hemolyzed relative to severely lipemic serum/plasma specimens. LD was the test most commonly affected by interference across all body fluid types. False elevations in pleural fluid LD induced by hemolysis can lead to mis-classification of transudative effusions as exudative using Light’s criteria. The possible impact of interferences on clinical chemistry testing in body fluids is an important post-analytical consideration.

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Hemolysis, icterus, and lipemia were evaluated in 2752 body fluid specimens.

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Distributions of interference indices in body fluids generally mimicked those of serum/plasma.

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Pancreatic and pericardial fluids had the highest proportion of tests exceeding the hemolysis index.

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Compared to serum/plasma, drain fluids had relatively more tests exceeding both icterus and lipemic limits.

Laboratory testing of extravascular body fluids: National recommendations on behalf of the Croatian Society of Medical Biochemistry and Laboratory Medicine. Part I - Serous fluids

Extravascular body fluids (EBF) analysis can provide useful information in the differential diagnosis of conditions that caused their accumulation. Their unique nature and particular requirements accompanying EBF analysis need to be recognized in order to minimize possible negative implications on patient safety. This recommendation was prepared by the members of the Working group for extravascular body fluid samples (WG EBFS). It is designed to address the total testing process and clinical significance of tests used in EBF analysis. The recommendation begins with a chapter addressing validation of methods used in EBF analysis, and continues with specific recommendations for serous fluids analysis. It is organized in sections referring to the preanalytical, analytical and postanalytical phase with specific recommendations presented in boxes. Its main goal is to assist in the attainment of national harmonization of serous fluid analysis and ultimately improve patient safety and healthcare outcomes. This recommendation is intended to all laboratory professionals performing EBF analysis and healthcare professionals involved in EBF collection and processing. Cytological and microbiological evaluations of EBF are beyond the scope of this document.

Educational Case: Regulatory Issues With Laboratory Testing

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.

Body Fluid Testing at John F. Kennedy Medical Center in Liberia

OBJECTIVES

To apply a simple method to validate testing for albumin, glucose, lactate dehydrogenase (LDH) and total protein (TP) in peritoneal, pleural, and cerebrospinal fluids (CSF) at a hospital in Liberia.

METHODS

Serum and body fluid specimens were mixed to create 100% serum and 25%, 50%, 75%, and 100% fluid tubes, which were tested on a Biotecnica BT3500. Differences less than 10% between calculated and measured concentrations were considered acceptable.

RESULTS

The means (confidence intervals) of the percent differences were: albumin/peritoneal 12.8 (6.0-19.7), albumin/pleural 2.8 (1.3-4.2), albumin/CSF 4.8 (2.2-7.5), glucose/peritoneal 4.0 (1.9-6.0), glucose/pleural 4.4 (3.1-5.7), glucose/CSF 2.9 (1.8-4.0), LDH/peritoneal 9.5 (6.3-12.7), LDH/pleural 9.5 (5.4-13.6), LDH/CSF 9.2 (5.2-13.3), TP/peritoneal 7.6 (3.8-11.4), TP/pleural 3.8 (1.5-6.2), and TP/CSF 4.5 (1.0-8.1).

CONCLUSIONS

All mean differences except for one were less than 10%, allowing for the adoption of clinical testing. The mixing study is a low-cost method for quality-assured testing that can be performed by resource-limited laboratories.

Peritoneal and Pleural Fluid Chemistry Measurements Performed on Three Chemistry Platforms

BACKGROUND

Chemistry testing is requested for body fluid (BF) specimens despite the lack of assays approved by the US Food and Drug Administration (FDA). The criteria for categorizing fluids as transudate or exudate are not validated across analyzers.

OBJECTIVE

To compare BF chemical analysis and classification by different analyzers.

METHODS

We analyzed 10 pleural and 18 peritoneal fluids with corresponding plasma specimens using the Vitros 5,1 FS; Abbott ARCHITECT ci8200; and Roche Modular P platforms. Total protein (TP) and lactate dehydrogenase (LDH) were measured for pleural fluids. Light's criteria were applied. Albumin was measured for peritoneal specimens, and the plasma-ascites-albumin gradient was calculated.

RESULTS

TP results showed agreement. The Vitros LDH assay produced higher fluid:plasma ratios. Classification by Light's criteria resulted in 1 discrepancy (ARCHITECT). Albumin results showed agreement. There were 2 discrepant gradient interpretations (Vitros).

CONCLUSIONS

These data suggest that analyses of pleural and peritoneal fluids using these platforms are diagnostically interchangeable.

Automated analysis for differentiating leukocytes in body fluids using the software "biological liquid application" on ADVIA2120/2120i hematology analyzer

INTRODUCTION

We evaluated the "Biological liquid application ADVIA2120" software for differentiating the percentage of polymorphonucleated (%PMN) and mononucleated cells (%MN) in ascitic, pleural, and peritoneal dialysis (PD) fluid.

METHODS

Biological fluid test results of 193 specimens obtained by automated methods (87 with and 106 without dedicated software) were compared with May-Grünwald-Giemsa (MGG) stained blood smears. Limit of detection (LoD) and quantitation (LoQ), repeatability, and inaccuracy were assessed.

RESULTS

Good agreement between the automated methods with dedicated software and the manual method for %PMN and %MN was obtained for leukocyte differentiation in ascitic and pleural fluids, while correlation with the manual method for PD fluid was poor, both with and without the dedicated software.

CONCLUSIONS

We demonstrated that the automated differentiation of leukocytes with dedicated software on the ADVIA2120 analyzer for body fluids is a good alternative to the microscopic reference method for peritoneal and pleural specimens, but not for PD fluids.

Extent of agreement between the body fluid model of Sysmex XN-20 and the manual microscopy method

BACKGROUND

Although the correlations concerning cellular component analysis between the Sysmex XN-20 body fluid (BF) model and manual microscopy have been investigated by several studies, the extent of agreement between these two methods has not been investigated.

METHODS

A total of 90 BF samples were prospectively collected and analyzed using the Sysmex XN-20 BF model and microscopy. The extent of agreement between these two methods was evaluated using the Bland-Altman approach. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic accuracy of high-fluorescence (HF) BF cells for malignant diseases.

RESULTS

The agreements of white blood cell (WBC), red blood cell (RBC), and percentages of neutrophils, lymphocytes, and monocytes between the Sysmex XN-20 BF model and manual microscopy were imperfect. The areas under the ROC curves for absolute and relative HF cells were 0.67 (95% confidence interval [CI]: 0.56-0.78) and 0.60 (95% CI: 0.48-0.72), respectively.

CONCLUSION

Due to the Sysmex XN-20 BF model's imperfect agreement with manual microscopy and its weak diagnostic accuracy for malignant diseases, the current evidence does not support replacing manual microscopy with this model in clinical practice.

Laboratory testing of extravascular body fluids in Croatia: a survey of the Working group for extravascular body fluids of the Croatian Society of Medical Biochemistry and Laboratory Medicine

INTRODUCTION

We hypothesized that extravascular body fluid (EBF) analysis in Croatia is not harmonized and aimed to investigate preanalytical, analytical and postanalytical procedures used in EBF analysis in order to identify key aspects that should be addressed in future harmonization attempts.

MATERIALS AND METHODS

An anonymous online survey created to explore laboratory testing of EBF was sent to secondary, tertiary and private health care Medical Biochemistry Laboratories (MBLs) in Croatia. Statements were designed to address preanalytical, analytical and postanalytical procedures of cerebrospinal, pleural, peritoneal (ascites), pericardial, seminal, synovial, amniotic fluid and sweat. Participants were asked to declare the strength of agreement with proposed statements using a Likert scale. Mean scores for corresponding separate statements divided according to health care setting were calculated and compared.

RESULTS

The survey response rate was 0.64 (58 / 90). None of the participating private MBLs declared to analyse EBF. We report a mean score of 3.45 obtained for all statements evaluated. Deviations from desirable procedures were demonstrated in all EBF testing phases. Minor differences in procedures used for EBF analysis comparing secondary and tertiary health care MBLs were found. The lowest scores were obtained for statements regarding quality control procedures in EBF analysis, participation in proficiency testing programmes and provision of interpretative comments on EBF's test reports.

CONCLUSIONS

Although good laboratory EBF practice is present in Croatia, procedures for EBF analysis should be further harmonized to improve the quality of EBF testing and patient safety.

Optimization of Cellular analysis of Synovial Fluids by optical microscopy and automated count using the Sysmex XN Body Fluid Mode

BACKGROUND

This study was planned to assess the impact of pre-treating synovial fluid (SF) samples with hyaluronidase (HY), defining the best procedure for optical microscopy (OM) analysis and evaluating the performance of Sysmex XN-9000 Body Fluid module (XN-BF).

METHODS

The cell count by OM was carried out both with and without HY pre-treatment, and using 3 different types of staining reagents. The evaluation of XN-BF included data comparison with OM (100 SFs), carryover, Limit of Blank (LoB), Limit of Detection (LoD), Limit of Quantitation (LoQ) and linearity.

RESULTS

Unlike cell count in Burker's chamber and staining with Stromatol, pre-treatment with HY and staining with Methylene Blue and Turk's promoted cell clustering. The SF samples pre-treated with HY displayed excellent morphological quality, contrary to samples without HY pre-treatment. Excellent correlation was found between total cells counting with both OM and XN-BF. Satisfactory agreement was also observed between polymorphonuclear neutrophils compared to XN-BF parameter, whereas mononuclear cell count on XN-BF had suboptimal agreement with OM. The carryover was negligible. The LoB, LoD, LoQ and linearity were excellent.

CONCLUSION

XN-BF displays excellent performance, which makes it a reliable and practical alternative to OM for SF samples analysis in clinical laboratories.

Filling in the gaps with non-standard body fluids

OBJECTIVES

Body fluid specimens other than serum, plasma or urine are generally not validated by manufacturers, but analysis of these non-standard fluids can be important for clinical diagnosis and management. Laboratories, therefore, rely on the published literature to better understand the validation and implementation of such tests. This study utilized a data-driven approach to determine the clinical reportable range for 11 analytes, evaluated a total bilirubin assay, and assessed interferences from hemolysis, icterus, and lipemia in non-standard fluids.

DESIGN AND METHODS

Historical measurements in non-standard body fluids run on a Beckman Coulter DxC800 were used to optimize population-specific clinical reportable ranges for albumin, amylase, creatinine, glucose, lactate dehydrogenase, lipase, total bilirubin, total cholesterol, total protein, triglyceride and urea nitrogen run on the Beckman Coulter AU680. For these 11 analytes, interference studies were performed by spiking hemolysate, bilirubin, or Intralipid® into abnormal serous fluids. Precision, accuracy, linearity, and stability of total bilirubin in non-standard fluids was evaluated on the Beckman Coulter AU680 analyzer.

RESULTS

The historical non-standard fluid results indicated that in order to report a numeric result, 4 assays required no dilution, 5 assays required onboard dilutions and 2 assays required both onboard and manual dilutions. The AU680 total bilirubin assay is suitable for clinical testing of non-standard fluids. Interference studies revealed that of the 11 total AU680 analyte measurements on non-standard fluids, lipemia affected 1, icterus affected 3, and hemolysis affected 5.

CONCLUSIONS

Chemistry analytes measured on the AU680 demonstrate acceptable analytical performance for non-standard fluids. Common endogenous interference from lipemia, icterus, and hemolysis (LIH) are observed and flagging rules based on LIH indices were developed to help improve the clinical interpretation of results.

Diagnostic Accuracy of Natriuretic Peptides for Heart Failure in Patients with Pleural Effusion: A Systematic Review and Updated Meta-Analysis

Background

Previous studies have reported that natriuretic peptides in the blood and pleural fluid (PF) are effective diagnostic markers for heart failure (HF). These natriuretic peptides include N-terminal pro-brain natriuretic peptide (NT-proBNP), brain natriuretic peptide (BNP), and midregion pro-atrial natriuretic peptide (MR-proANP). This systematic review and meta-analysis evaluates the diagnostic accuracy of blood and PF natriuretic peptides for HF in patients with pleural effusion.

Methods

PubMed and EMBASE databases were searched to identify articles published in English that investigated the diagnostic accuracy of BNP, NT-proBNP, and MR-proANP for HF. The last search was performed on 9 October 2014. The quality of the eligible studies was assessed using the revised Quality Assessment of Diagnostic Accuracy Studies tool. The diagnostic performance characteristics (sensitivity, specificity, and other measures of accuracy) were pooled and examined using a bivariate model.

Results

In total, 14 studies were included in the meta-analysis, including 12 studies reporting the diagnostic accuracy of PF NT-proBNP and 4 studies evaluating blood NT-proBNP. The summary estimates of PF NT-proBNP for HF had a diagnostic sensitivity of 0.94 (95% confidence interval [CI]: 0.90–0.96), specificity of 0.91 (95% CI: 0.86–0.95), positive likelihood ratio of 10.9 (95% CI: 6.4–18.6), negative likelihood ratio of 0.07 (95% CI: 0.04–0.12), and diagnostic odds ratio of 157 (95% CI: 57–430). The overall sensitivity of blood NT-proBNP for diagnosis of HF was 0.92 (95% CI: 0.86–0.95), with a specificity of 0.88 (95% CI: 0.77–0.94), positive likelihood ratio of 7.8 (95% CI: 3.7–16.3), negative likelihood ratio of 0.10 (95% CI: 0.06–0.16), and diagnostic odds ratio of 81 (95% CI: 27–241). The diagnostic accuracy of PF MR-proANP and blood and PF BNP was not analyzed due to the small number of related studies.

Conclusions

BNP, NT-proBNP, and MR-proANP, either in blood or PF, are effective tools for diagnosis of HF. Additional studies are needed to rigorously evaluate the diagnostic accuracy of PF and blood MR-proANP and BNP for the diagnosis of HF.

Physiology of pericardial fluid production and drainage

The pericardium is one of the serosal cavities of the mammals. It consists of two anatomical structures closely connected, an external sac of fibrous connective tissue, that is called fibrous pericardium and an internal that is called serous pericardium coating the internal surface of the fibrous pericardium (parietal layer) and the heart (visceral layer) forming the pericardial space. Between these two layers a small amount of fluid exists that is called pericardial fluid. The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly. Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics. Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated.