Preservation of urine specimens for metabolic evaluation of recurrent urinary stone formers.

OBJECTIVES: Stability of concentrations of urinary stone-related metabolites was analyzed from samples of recurrent urinary stone formers to assess necessity and effectiveness of urine acidification during collection and storage. METHODS: First-morning urine was collected from 20 adult calcium-stone forming patients at Tomas Bata Hospital in the Czech Republic. Urine samples were analyzed for calcium, magnesium, inorganic phosphate, uric acid, sodium, potassium, chloride, citrate, oxalate, and urine particles. The single-voided specimens were collected without acidification, after which they were divided into three groups for storage: samples without acidification ("NON"), acidification before storage ("PRE"), or acidification after storage ("POST"). The analyses were conducted on the day of arrival (day 0, "baseline"), or after storage for 2 or 7 days at room temperature. The maximum permissible difference (MPD) was defined as ±20 % from the baseline. RESULTS: The urine concentrations of all stone-related metabolites remained within the 20 % MPD limits in NON and POST samples after 2 days, except for calcium in NON sample of one patient, and oxalate of three patients and citrate of one patient in POST samples. In PRE samples, stability failed in urine samples for oxalate of three patients, and for uric acid of four patients after 2 days. Failures in stability often correlated with high baseline concentrations of those metabolites in urine. CONCLUSIONS: Detailed procedures are needed to collect urine specimens for analysis of urinary stone-related metabolites, considering both patient safety and stability of those metabolites. We recommend specific preservation steps.

The EFLM European Urinalysis Guideline 2023.

BACKGROUND: The EFLM Task and Finish Group Urinalysis has updated the ECLM European Urinalysis Guidelines (2000) on urinalysis and urine bacterial culture, to improve accuracy of these examinations in European clinical laboratories, and to support diagnostic industry to develop new technologies. RECOMMENDATIONS: Graded recommendations were built in the following areas. MEDICAL NEEDS AND TEST REQUISITION: Strategies of urine testing are described to patients with complicated or uncomplicated urinary tract infection (UTI), and high or low-risk to kidney disease. SPECIMEN COLLECTION: Patient preparation, and urine collection are supported with two quality indicators: contamination rate (cultures), and density of urine (chemistry, particles). CHEMISTRY: Measurements of both urine albumin and α1-microglobulin are recommended for sensitive detection of kidney disease in high-risk patients. Performance specifications are given for urine protein measurements and quality control of multiproperty strip tests. PARTICLES: Procedures for microscopy are reviewed for diagnostic urine particles, including urine bacteria. Technologies in automated particle counting and visual microscopy are updated with advice how to verify new instruments with the reference microscopy. BACTERIOLOGY: Chromogenic agar is recommended as primary medium in urine cultures. Limits of significant growth are reviewed, with an optimised workflow for routine specimens, using leukocyturia to reduce less important antimicrobial susceptibility testing. Automation in bacteriology is encouraged to shorten turn-around times. Matrix assisted laser desorption ionization time-of-flight mass spectrometry is applicable for rapid identification of uropathogens. Aerococcus urinae, A. sanguinicola and Actinotignum schaalii are taken into the list of uropathogens. A reference examination procedure was developed for urine bacterial cultures.

Verifying measurements on Siemens Atellica® instruments using clinically acceptable analytical performance specifications.

Measurements on clinical chemistry analysers must be verified to demonstrate applicability to their intended clinical use. We verified the performance of measurements on the Siemens Atellica® Solution chemistry analysers against the clinically acceptable analytical performance specifications, CAAPS, including the component of intra-individual biological variation, CVI. The relative standard uncertainty of measurement, i.e. analytical variation, CVA, was estimated for six example measurands, haemoglobin A1c in whole blood (B-HbA1c), albumin in urine (U-Alb), and the following measurands in plasma: sodium (P-Na), pancreatic amylase (P-AmylP), low-density lipoprotein cholesterol (P-LDL-C), and creatinine (P-Crea). Experimental CVA was calculated from single-instrument imprecision using control samples, variation between measurements on parallel instruments, and estimation of bias with pooled patient specimens. Each obtained CVA was compared with previously developed CAAPS. The calculated CVA was 1.4% for B-HbA1c (CAAPS 1.9% for single diagnostic testing, CAAPS 2.0% for monitoring after duplicate tests; IFCC units), 10.9% for U-Alb (CAAPS 44.9%), 1.2% for P-Na (CAAPS 0.6%, after triplicate testing 1.5%), 8.2% for P-AmylP (CAAPS 22.9%). The CVA was 4.9% for P-LDL-C (CAAPS for cardiovascular risk stratification 4.9% after four replicates), and 4.2% for P-Crea (CAAPS 8.0%). Three of the six measurands fulfilled the estimated clinical need. Results from P-Na measurements indicate a general need for improving the P-Na assays for emergency patients. It is necessary to consider CVI when creating diagnostic targets for laboratory tests, as emphasised by the CAAPS estimates of B-HbA1c and P-LDL-C.

External quality assessment of urine particle identification: a Northern European experience.

External quality assessment (EQA) schemes for urinalysis have been provided by Labquality Ltd, the publicly owned EQA service provider in Finland, since the 1980s. In 2014, the scheme on urine particle identification had 329 participating laboratories, out of which 60% from 19 countries were outside Finland. Each of the four annual web-based rounds were distributed with four Sternheimer-stained images from a single patient sample, as viewed both by bright-field and phase-contrast optics. Participants reported classified categories either at the basic or at the advanced level. Participating laboratories received assessment of their analytical performance as compared to their peers, including reflections from clinical data and preanalytical detail of the specimen. In general, reporting of basic urine particles succeeded in the eight schemes during the years 2013-2014 as follows: red blood cells 82%-92%, white blood cells 82%-97%, squamous epithelial cells 92%-98%, casts 84%-94%, and small epithelial cells 73%-83% (minimum and maximum of expected or accepted reports). This basic level of differentiation is used in routine laboratory reports, or as verification of results produced by automated instruments. Considerable effort is needed to standardise national procedures and reporting formats, in order to improve the shown figures internationally. Future technologies may help to alleviate limitations created by single digital images. Despite improvements, degenerating cells and casts always exhibit intermediate forms creating disputable classifications. That is why assessment of performance should encompass justified acceptable categories into the assessed outcomes. Preanalytical and clinical detail provide essential added value to morphological findings.

Clinical decision limits as criteria for setting analytical performance specifications for laboratory tests.

BACKGROUND: The biological (CVI), preanalytical (CVPRE), and analytical variation (CVA) are inherent to clinical laboratory testing and consequently, interpretation of clinical test results. METHODS: The sum of the CVI, CVPRE, and CVA, called diagnostic variation (CVD), was used to derive clinically acceptable analytical performance specifications (CAAPS) for clinical chemistry measurands. The reference change concept was applied to clinically significant differences (CD) between two measurements, with the formula CD = z*√2* CVD. CD for six measurands were sought from international guidelines. The CAAPS were calculated by subtracting variances of CVI and CVPRE from CVD. Modified formulae were applied to consider statistical power (1-ß) and repeated measurements. RESULTS: The obtained CAAPS were 44.9% for urine albumin, 0.6% for plasma sodium, 22.9% for plasma pancreatic amylase, and 8.0% for plasma creatinine (z = 3, α = 2.5%, 1-ß = 85%). For blood HbA1c and plasma low-density lipoprotein cholesterol, replicate measurements were necessary to reach CAAPS for patient monitoring. The derived CAAPS were compared with analytical performance specifications, APS, based on biological variation. CONCLUSIONS: The CAAPS models pose a new tool for assessing APS in a clinical laboratory. Their usability depends on the relevance of CD limits, required statistical power and the feasibility of repeated measurements.

Analytical performance of the Iris iQ200 automated urine microscopy analyzer.

BACKGROUND: We evaluated the Iris iQ200 Automated Urine Microscopy Analyzer to find out if the instrument performed better than traditional visual bright field microscopy in detecting basic urine particles, as assessed against reference phase contrast microscopy. METHODS: The HUSLAB quality system was followed in planning and completing the evaluation process. The iQ200 instrument results from 167 mid-stream, uncentrifuged urine specimens were compared to those obtained with phase contrast reference microscopy, and to those with routine bright field microscopy. Linearity, carry-over and precision were tested according to well-established protocols. RESULTS: The iQ200 counted erythrocytes (RBC) at r=0.894 (R(2)=0.799) with Automated Particle Recognition (APR) software alone and at r=0.948 (R(2)=0.898) after re-classification. The performance for leukocytes (WBC) was r=0.885 with APR and r=0.978 after re-classification. The correlations of counting after user re-classification were r=0.927 for squamous epithelial cells (SQEP), r=0.856 for casts, and r=0.706 for non-squamous epithelial cells. The iQ200 showed good linearity and precision and no carry-over was detected. CONCLUSIONS: The Iris iQ200 was capable to count reliably RBC, WBC, and SQEP cells and to identify a fraction of bacteria and renal elements. Counting results equalled or exceeded that of routine bright field microscopy or earlier flow cytometric technology. The instrument eliminates manual sample preparation but requires a well-trained technologist for re-grouping of findings.

From customer satisfaction survey to corrective actions in laboratory services in a university hospital.

OBJECTIVE: To find out the satisfaction of clinical units with laboratory services in a university hospital, to point out the most important problems and defects in services, to carry out corrective actions, and thereafter to identify the possible changes in satisfaction. SETTING: and STUDY PARTICIPANTS: Senior physicians and nurses-in-charge of the clinical units at Oulu University Hospital, Finland. DESIGN: Customer satisfaction survey using a questionnaire was carried out in 2001, indicating the essential aspects of laboratory services. Customer-specific problems were clarified, corrective actions were performed, and the survey was repeated in 2004. RESULTS: In 2001, the highest dissatisfaction rates were recorded for computerized test requesting and reporting, turnaround times of tests, and the schedule of phlebotomy rounds. The old laboratory information system was not amenable to major improvements, and it was renewed in 2004-05. Several clinical units perceived turnaround times to be long, because the tests were ordered as routine despite emergency needs. Instructions about stat requesting were given to these units. However, no changes were evident in the satisfaction level in the 2004 survey. Following negotiations with the clinics, phlebotomy rounds were re-scheduled. This resulted in a distinct increase in satisfaction in 2004. CONCLUSIONS: Satisfaction survey is a screening tool that identifies topics of dissatisfaction. Without further clarifications, it is not possible to find out the specific problems of customers and to undertake targeted corrective actions. Customer-specific corrections are rarely seen as improvements in overall satisfaction rates.