Ascorbic acid-A black hole of urine chemistry screening

Evaluation of AgNCs@PEI and their integrated hydrogel for colorimetric and fluorometric detection of ascorbic acid

A dual-mode colorimetric and fluorometric sensor based on water soluble silver nanoclusters (AgNCs@PEI) is developed for quantitative and visual detection of ascorbic acid (Asc A). The detection method relies on the Asc A induced aggregation of AgNCs@PEI, which resulted in fluorecsence quenching of the sensor. The clusters exhibited a unique combination of static and collisional quenching with a wide range of dynamic detection (1-105 µM) Linear relationship was observed in the concentration range 102-103 µM using fluorescence and 0.2 × 102-5 × 103 μM using absorbance spectroscopy with respective detection limits of 10.65 μM and 2.49 μM. The corresponding colorimetric and fluorometric changes can be easily monitored by the naked eye with a visual detection limit of 103 μM. AgNCs@PEI were further integrated within a hydrogel for developing a solid-state visual detection platform. Notably, the sensing response of the clusters towards Asc A remained unaltered even after hydrogel integration. Additionally, digital image analysis was adopted, which improved the sensitivity of instrument-free fluorescence detection of Asc A. Analysis by the developed sensor showed excellent recovery percentages of Asc A in spiked urine samples, which further underscores the practical applicability of the sensor.

Electrochemical Diagnosis of Urinary Tract Infection Using Boron-Doped Diamond Electrodes

Efficient detection of sodium nitrite in human urine could be used to diagnose urinary tract infections rapidly. Here, we demonstrate a fast and novel method for the selective detection of sodium nitrite in different human urine samples using electrolysis with a bare boron-doped diamond electrode. The measurement is performed without adding any other species, such as enzymes, and uses a simple electrochemical approach with an oxidation step followed by reduction. In the present study, we pay attention to the reduction potential range for the measurement, which is substantially different from many previous literature reports that focus on the oxidation reaction. The determination of added sodium nitrite based on cyclic voltammetry or differential pulse voltammetry is employed for two pooled urine samples and three individual urine matrices. From this, the linear response ranges for sodium nitrite detection are 0.5-10 mg/L (7.2-140 μmol/L) and 10-400 mg/L (140-5800 μmol/L). The results from these urine samples convert well to the calibration curve, with a limit of detection established as 0.82 mg/L (R2 = 0.9914), which is clinically relevant.

Performance evaluation of Hipee S2 point-of-care testing urine dipstick analyser: a cross-sectional study

OBJECTIVE

With advances in mobile technology, smartphone-based point-of-care testing (POCT) urinalysis hold great potential for disease screening and health management for clinicians and individual users. The purpose of this study is to evaluate the analytical performance of Hipee S2 POCT urine dipstick analyser.

DESIGN

A multicentre, hospital-based, cross-sectional study.

SETTING

Analytical performance of the POCT analyser was conducted at a clinical laboratory, and method comparison was performed at three clinical laboratories in China.

PARTICIPANTS

Urine samples were collected from 1603 outpatients and inpatients at three hospitals, and 5 health check-up population at one of the hospitals.

OUTCOME MEASURES

All tests were performed by clinical laboratory technicians. Precision, drift, carry-over, interference and method comparison of Hipee S2 were evaluated. Diagnostic accuracy of semiquantitative albumin-to-creatinine ratio (ACR) for albuminuria was carried out using quantitative ACR as the standard.

RESULTS

The precision for each parameter, assessed by control materials, was acceptable. No sample carry-over or drift was observed. Ascorbate solution with 1 g/L had an inhibitory effect for the haemoglobin test. Agreement for specific gravity (SG) varied between moderate to substantial (κ values 0.496-0.687), for pH was moderate (κ values 0.423-0.569) and for other parameters varied between substantial to excellent (κ values 0.669-0.991), on comparing the Hipee S2 with laboratory analysers. The semiquantitative microalbumin and creatinine were highly correlated with the quantitative results. The sensitivity of semiquantitative ACR to detect albuminuria was 87.2%-90.7%, specificity was 70.7%-78.4%, negative predictive value was 85.3%-87.9% and positive predictive value was 73.9%-83%.

CONCLUSIONS

Hipee S2 POCT urine analyser showed acceptable analytical performance as a semiquantitative method. It serves as a convenient alternate device for clinicians and individual users for urinalysis and health management. In addition, the POCT semiquantitative ACR would be useful in screening for albuminuria.

Revisiting approaches to and considerations for urinalysis and urine culture reflexive testing

Urinalysis is considered the world's oldest laboratory test. Today, many laboratories use macroscopic urinalysis as a screening tool to determine when to subject urine samples for a microscopic urinalysis and/or bacterial culture. While reflexive urine microscopy has been practiced for decades, and reflexive urine culture, more recently, evidence-based guidelines regarding optimal reflexive criteria and workflows are lacking. Standard approaches are hindered, in part, by a lack of harmonization of urinalysis and urine culture practices, heterogeneity in patient populations that are studied, and lack of provider adherence to recommended practices. This review summarizes studies that have evaluated the performance of reflexive urine microscopy and reflexive urine culture, particularly in the context of urinary tract infections. It also examines reported clinical outcomes from reflexive urinalysis interventions and their impact on antibiotic stewardship efforts. Finally, it discusses laboratory operational considerations for the implementation of reflexive algorithms.

Discrepancy in results between dipstick urinalysis and urine sediment microscopy

With the advancement of urine test automation and the large-scale application of quality management policies, the source of the most crucial errors has become the pre-analytical phase. This study is an attempt to compare the results obtained from the examination of urine strips with those obtained by microscopic examination of urinary sediment, highlighting discordant results. This observational study was conducted between February and August 2019 in a private medical laboratory in Mureş County, and 2,600 urine samples were analyzed. We calculated the sensitivity, specificity, positive predictive value, negative predictive value for leukocytes, nitrites and red blood cells, taking as reference the microscopic examination of urine summary screening. Urine samples were collected from patients who presented to the laboratory. The 2,600 urine samples were analyzed using strips with 10 parameters: glucose, protein, bilirubin, urobilinogen, pH, specific density, red blood cells, nitrite, and leukocytes, and then using the microscope to examine the urinary sediment. We identified a small percentage (1.92%) of inconsistencies from the 2,600 samples of urine, between urinalysis and the microscopic examination and we identified the causes. The most common discordant results were: false-negatives for nitrite (72%), followed by false-positives results for red blood cells (22%), false-negative results for leukocytes (16%), false-negative results for red blood cells (4%) and false-positives for leukocytes (4%). The study confirmed that discrepancies appear despite the proper instruction of patients.

Vitamin C and kidney transplantation: Nutritional status, potential efficacy, safety, and interactions

BACKGROUND AND AIM

There are several observational and interventional studies regarding the advantages of sufficient serum levels of vitamin C and the evaluation of the effects of vitamin C supplementation post kidney transplantation. These studies have been put together to investigate the role of vitamin C post-kidney transplantation and make suggestions for designing future studies based on the use of vitamin C supplements or nutritional interventions among these patients.

METHODS

This narrative review was done by searching in the Embase, PubMed, and SCOPUS databases.

RESULTS

The results are presented in several sections as follows; nutritional status, potential protective effects, safety concerns, and medications/laboratory tests interactions of vitamin C.

CONCLUSIONS

Kidney transplant recipients are prone to vitamin C deficiency, which is related to higher mortality based on several long-term observational studies. Vitamin C supplementation improves endothelial function and creatinine clearance. Vitamin C is considered as a safe supplement, however, side effects such as kidney stones, pro-oxidant effect, hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency, impact on lymphocytic activity, acid-base disturbance, and increased sodium load following its administration have been reported. Interaction of vitamin C and cyclosporine is the most important interaction with post-renal transplant medications. Vitamin C also interferes with creatinine assay using Jaffe and enzymatic methods.

Pain management after open liver resection: Procedure-Specific Postoperative Pain Management (PROSPECT) recommendations

Background and objectives

Effective pain control improves postoperative rehabilitation and enhances recovery. The aim of this review was to evaluate the available evidence and to develop recommendations for optimal pain management after open liver resection using Procedure-Specific Postoperative Pain Management (PROSPECT) methodology.

Strategy and selection criteria

Randomized controlled trials (RCTs) published in the English language from January 2010 to October 2019 assessing pain after liver resection using analgesic, anesthetic or surgical interventions were identified from MEDLINE, Embase and Cochrane databases.

Results

Of 121 eligible studies identified, 31 RCTs and 3 systematic reviews met the inclusion criteria. Preoperative and intraoperative interventions that improved postoperative pain relief were non-steroidal anti-inflammatory drugs, continuous thoracic epidural analgesia, and subcostal transversus abdominis plane (TAP) blocks. Limited procedure-specific evidence was found for intravenous dexmedetomidine, intravenous magnesium, intrathecal morphine, quadratus lumborum blocks, paravertebral nerve blocks, continuous local anesthetic wound infiltration and postoperative interpleural local anesthesia. No evidence was found for intravenous lidocaine, ketamine, dexamethasone and gabapentinoids.

Conclusions

Based on the results of this review, we suggest an analgesic strategy for open liver resection, including acetaminophen and non-steroidal anti-inflammatory drugs, combined with thoracic epidural analgesia or bilateral oblique subcostal TAP blocks. Systemic opioids should be considered as rescue analgesics. Further high-quality RCTs are needed to confirm and clarify the efficacy of the recommended analgesic regimen in the context of an enhanced recovery program.

Direct microfluidic antibiotic resistance testing in urine with smartphone capture: significant variation in sample matrix interference between individual human urine samples

Direct antibiotic susceptibility tests for urinary tract infections should be assessed using a wide range of individual urine samples to identify matrix interference.

Double false-negative traps in urine routine test: a case report

Background

Urinalysis is one of the most commonly performed tests in clinical practice and supplies important information for a series of clinical conditions, including renal and urinary tract diseases. The clinical laboratory often completes urinalysis through the combined use of urinary dry-chemistry and formed-element analyzers. Urine red blood cell (RBC) morphology test is often used to discriminate the source of hematuria by manual microscopy.

Case presentation

In this case report, we describe a 39-year-old woman with chronic glomerulonephritis (CGN) who underwent both urine routine test and RBC morphology test. Her RBC count was in the normal range and the occult blood test was negative in routine test, while the RBC morphology test indicated the presence of non-homogeneous hematuria.

Conclusions

Therefore, we analyzed the causes of false-negative result on the urine chemical analyzer and the automatic microscope system, respectively.

Ascorbic acid in urine still compromises urinalysis results

Background

The aim of this work was to determine the frequency of ascorbic acid-positive urine samples and to evaluate the potential risk on patient safety.

Materials and methods

A total of  27,856 samples submitted for urinalysis in previous year were retrospectively analysed from the laboratory information system. Urinalysis was done on Iris IQ200 analyzer using 11-parameter iChem Velocity test strips. Risk analysis combined the impact of potentially erroneous results (due to ascorbic acid interference) on patient safety (severity – S) with their frequency (occurrence – O). Potential risk was identified as high, intermediate and low.

Results

One thousand one hundred and ninety-nine (4.3%) and 1646 (5.9%) samples were mildly (20 mg/dL, 1+) and highly positive (40 mg/dL, 2+) for ascorbic acid, respectively. Severity (S1 to S5) was assigned to four possible errors: false-negative glucose (U-Glc: S2), blood (U-Hb: S5), nitrite (U-Nit: S4) and bilirubin (U-Bil: S1). Based on the frequency of errors, occurrence was categorized as: O2 for U-Glc, and O3 for U-Bil, U-Nit and U-Hb. The risk analysis matrix revealed that false-negative U-Hb was associated with potentially high risk, false-negative U-Nit with intermediate risk, while false-negative U-Glc and U-Bil were associated with low risk on patient safety.

Conclusions

Positive ascorbic acid can cause potentially high risk for patient safety by missing positive blood in urine.

Ascorbic acid-A black hole of urine chemistry screening

BACKGROUND

Study was performed in order: (i) to assess the comparability of glucose, bilirubin, hemoglobin, leukocyte esterase, and protein; (ii) to assess accuracy of glucose, bilirubin, hemoglobin, leukocyte esterase, and protein; and (iii) to evaluate interference of ascorbic acid on the glucose, bilirubin, hemoglobin, and nitrite determination using 2 different dipsticks: iChem Velocity, Iris Diagnostics and Combur-10M, Roche Diagnostics.

METHODS

Random urine specimens were included in the study. Comparability, accuracy, and ascorbic acid interference testing were performed.

RESULTS

Obtained results have shown almost perfect agreement for all parameters between 2 dipsticks in samples with negative ascorbic acid. Agreement in samples with positive ascorbic acid was not acceptable for bilirubin, protein, nitrite, and hemoglobin. Accuracy was not acceptable for hemoglobin and leukocyte esterase on both dipsticks. Ascorbic acid interference examination has shown that intensity of interference differs between dipsticks. Ascorbic acid interferes with glucose, hemoglobin, nitrite, and bilirubin at different concentrations causing false-negative results.

CONCLUSION

Obtained results indicate that it is necessary to determine diagnostic accuracy of used dipstick in order to define purpose of urinalysis. It is very important to choose dipstick with ascorbic acid indicator and to examine ascorbic acid impact on dipstick analytes independently of manufacturer claims.