Abstract
IntroductionLaboratories often modify procedures recommended by the European Urinalysis Guidelines for urine sediment analysis. The aim of this study was to compare the recommended protocol with our routine laboratory procedure and to evaluate the possible impact of modifications in the relative centrifugal force, type of tube, method of supernatant aspiration and urine volume on patient’s results.Material and methodsFirstly, relative centrifugal force was investigated using 20 pairs of samples examined after centrifugation at 400xg and 1358xg. In phase two, 110 samples were examined, paired as: round bottom vs conical tube (N = 46), decanting vs suction of supernatant (N = 100) and 10 mL vs 5 mL of urine sample (N = 101).ResultsThe number of erythrocytes, leukocytes and squamous epithelial cells was significantly lower after centrifugation at 400xg (P = 0.001, 0.002 and 0.004, respectively). The number of leukocytes was significantly lower in conical tubes (P = 0.010), after the suction of supernatant (P = 0.045) and in 5 mL urine (P < 0.001). The number of squamous epithelial cells was significantly lower after the suction of supernatant (P < 0.001) and in 5 mL urine (P < 0.001). The number of erythrocytes (P < 0.001), total non-hyaline casts (P < 0.001) and the frequency of granular casts (P = 0.039) was significantly lower in 5 mL urine.ConclusionLower results of leukocytes, erythrocytes, squamous cells and non-hyaline casts were recorded in recommended procedures (centrifugation at 400xg, suction of supernatant, conical tube, 5 mL of sample) than in routine procedure (centrifugation at 1358xg, decanting of supernatant, round bottom tube, 10 mL) used in our laboratory.
Highlights
Laboratories often modify procedures recommended by the European Urinalysis Guidelines for urine sediment analysis
Lower results of leukocytes, erythrocytes, squamous cells and non-hyaline casts were recorded in recommended procedures than in routine procedure used in our laboratory
For all quantitative parameters, significantly lower values were observed when urine sediment was centrifuged at 400xg (P = 0.001, 0.002 and 0.004, respectively)
Summary
Laboratories often modify procedures recommended by the European Urinalysis Guidelines for urine sediment analysis. The aim of this study was to compare the recommended protocol with our routine laboratory procedure and to evaluate the possible impact of modifications in the relative centrifugal force, type of tube, method of supernatant aspiration and urine volume on patient’s results. Qualitative urinalysis includes visual inspection of urine, chemical analysis and microscopic analysis of urinary sediment [1]. Elements of urine sediment are divided in two groups, organized and unorganized elements. Organized urine sediment consists of biological elements such as leukocytes, erythrocytes, epithelial cells, casts, bacteria, fungi, parasites and sperm. Years of practice and vast experience are required for accurate identification and classification of urine sediment elements [2]
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