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Urine contains an enormous amount of information. Well-standardized procedures for collection, transport, sample
preparation and analysis should become the basis of an effective diagnostic strategy for urinalysis. As reproducibility of urinalysis has been greatly improved due to recent technological progress, preanalytical requirements of urinalysis have gained importance and have become stricter. Since the patients themselves often collect urine specimens, urinalysis is very susceptible to preanalytical issues. Various collection methods and inappropriate specimen transport can cause important preanalytical errors. In addition to the insurance of correct collection, the clinical laboratory should optimize transport and sample preservation. Errors due to variation in diuresis may be corrected by recalculating the results using dilution parameters (e.g. osmolality, creatinine, conductivity, urine density). Next to the use of a primary urine container, it is recommended to split the original urine sample into various smaller aliquots for morphological, microbiological and chemical analyses, decreasing the risk of contamination. The use of preservatives may be helpful for particular analytes. A universal urine preservative however does not exist. Preanalytical aspects are also of major importance for newer urinalysis applications (e.g. metabolomics).

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Timo Kouri a*, Walter Hofmann b, Rosanna Falbo c, Matthijs Oyaert d,
Sören Schubert e, Jan Berg Gertsen f, Audrey Merens g, and Martine Pestel-Caron h,on behalf of the EFLM European Urinalysis Group.
a Department of Clinical Chemistry, University of Helsinki, and HUSLAB, HUS Diagnostic Center,
Hospital District of Helsinki and Uusimaa, Helsinki, Finland
b Synlab MVZ, Augsburg and Dachau, Germany
c University Department of Laboratory Medicine, ASST Brianza, Pio XI Hospital, Desio (MB), Italy
d Department of Laboratory Medicine, University Hospital Ghent, Ghent, Belgium
e Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, Ludwig
Maximilian University, Munich, Germany

Background: The EFLM Task and Finish Group Urinalysis has updated the ECLM European Urinalysis Guidelines (2000) on laboratory procedures in urinalysis and urine bacterial culture. We aim to improve accuracy of urine 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 were described to patients with low and high-risk to urinary tract infection (UTI) or kidney disease.
Specimen collection: Patient preparation, and urine collection are now 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 renal disease in high-risk patients. Performance specifications for urine protein measurements and quality control of multiproperty strip tests were given.
Particles: Procedures for microscopy were reviewed for diagnostic urine particles, including urine bacteria. Technologies in automated particle counting were updated with advice how to verify new instruments with the reference microscopy.
Bacteriology: Chromogenic agar was recommended as primary medium in urine cultures. Limits of significant growth were 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 were taken into the list of uropathogens. Moreover, a reference examination procedure was developed for urine bacterial cultures.
Key words: automation; laboratory practice guidelines; reference measurement procedures; standardisation; urinalysis; urine bacterial culture

Am Fam Physician. 2005 Mar 15;71(6):1153-1162.

A complete urinalysis includes physical, chemical, and microscopic examinations. Midstream clean collection is acceptable in most situations, but the specimen should be examined within two hours of collection. Cloudy urine often is a result of precipitated phosphate crystals in alkaline urine, but pyuria also can be the cause. A strong odor may be the result of a concentrated specimen rather than a urinary tract infection. Dipstick urinalysis is convenient, but false-positive and false-negative results can occur. Specific gravity provides a reliable assessment of the patient’s hydration status. Microhematuria has a range of causes, from benign to life threatening. Glomerular, renal, and urologic causes of microhematuria often can be differentiated by other elements of the urinalysis. Although transient proteinuria typically is a benign condition, persistent proteinuria requires further work-up. Uncomplicated urinary tract infections diagnosed by positive leukocyte esterase and nitrite tests can be treated without culture.

BEDSIDE URINARY MICROSCOPY
GIOVANNI BATTISTA FOGAZZI LECTURES SERIES
G.B. Fogazzi, Milan, Italy

Urinary Microscopy Part I

Urinary Microscopy Part II

Urinary Microscopy Part III

Urinary Microscopy Part IV

Urinary Microscopy Part V

Urinary Microscopy Part VI