[Detection and identification of urinary crystals using an automated urine particle analyzer coupled with a digital particle imaging device]. / Détection et identification de cristaux dans les urines à l'aide d'un analyseur de cytologie urinaire couplé à un dispositif d'imagerie numérique.

Polarized light microscopy (POM) remains the gold standard for crystalluria analysis. However, such method is time consuming and requires well-trained staff. Here, to address this issue, we tested the Sysmex UF-4000 analyzer coupled to a UD10 module as an automated flow cytometry-digital particle imaging workflow to assess (i) the ability of the system to detect and identify the crystals species and (ii) the quality of the images provided by the UD-10 module (n = 40) for each urine sample analyzed. First, systematic analysis of 76 samples by POM and the UF-4000/UD-10 analyzer showed that only attentive examination of the 40 photos was able to confidently detect crystalluria-positive samples with no misses and thus serve to discriminate positive-test crystalluria from negative-test crystalluria. These first results were confirmed by sensitivity analysis and the negative predictive value calculated on 200 samples for the results provided by the UF-4000 (39% and 46%) and after examination of the 40 UD-10 photos (100% for the both values). Digital images can therefore serve to screen crystalluria without missing crystals. A part of samples were treated by POM whereas it was not necessary (positive predictive value: 78%). Finally, we compared the crystal identification performances of the Sysmex UF4000/UD10 workflow and the 'gold standard' POM method on 131 urine samples containing crystals. Only calcium oxalate dihydrate crystals were identified by the Sysmex UF-4000. A close examination of the digital photographs enabled exact identification of crystals in 84.7% of the samples, suggesting however that POM is still require as soon as crystals are observed on the photographs. We conclude that a SYSMEX UF-4000 coupled with a UD-10 module can be used in practice with close examination of the photographs to discriminate positive crystalluria from negative crystalluria.

Preanalytical influence of pneumatic tube delivery system on results of routine biochemistry and haematology analysis.

Pneumatic tube delivery system (PTS) enables to reduce considerably turnaround times. The aim of the study was to assess the influence of the PTS on the quality of routine biochemical and hematological tests in our laboratory. Blood samples from 6 hospitalized patients and 8 healthy volunteers were analyzed. Blood samples were delivered to the laboratory by a PTS and by a human courier. We performed the following analysis: ionized calcium, sodium, potassium, lactate deshydrogenase (LDH), aspartate aminotransferase (ASAT), arterial blood gas, complete blood count and coagulation test as prothrombin time, activated partial thromboplastin time, factors V and VIII. Results were compared between the both method of transport according to the recommendation of the Société française de biologie clinique and the French committee for accreditation (SH-GTA01, norme NF ISO 5275-6). The hemolysis index of plasma was similar between the groups and no morphological differences were found on blood cells. For three samples, when delivered by PTS, LDH levels (two samples) and neutrophil polynuclear count (one sample) were above the recommended guidelines compared to those delivered by courier. Conversely, LDH levels and FVIII were below in two samples delivered by PTS. LDH levels, PNN count or factor VIII can be affected by PTS without the clinical interpretation being modified. We concluded that the PTS can be used to transport blood samples for routine biochemical and hematological analysis in our hospital.

Is a pre-analytical process for urinalysis required?

For the reliable urinary measurement of calcium, phosphate and uric acid, a pre-analytical process by adding acid or base to urine samples at laboratory is recommended in order to dissolve precipitated solutes. Several studies on different kind of samples and analysers have previously shown that a such pre-analytical treatment is useless. The objective was to study the necessity of pre-analytical treatment of urine on samples collected using the V-Monovette® (Sarstedt) system and measured on the analyser Architect C16000 (Abbott Diagnostics). Sixty urinary samples of hospitalized patients were selected (n=30 for calcium and phosphate, and n=30 for uric acid). After acidification of urine samples for measurement of calcium and phosphate, and alkalinisation for measurement of uric acid respectively, differences between results before and after the pre-analytical treatment were compared to acceptable limits recommended by the French society of clinical biology (SFBC). No difference in concentration between before and after pre-analytical treatment of urine samples exceeded acceptable limits from SFBC for measurement of calcium and uric acid. For phosphate, only one sample exceeded these acceptable limits, showing a result paradoxically lower after acidification. In conclusion, in agreement with previous study, our results show that acidification or alkalinisation of urine samples from 24 h urines or from urination is not a pre-analytical necessity for measurement of calcium, phosphate and uric acid.