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Mid-stream vs. first-voided urine collection by using automated analyzers for particle examination in healthy subjects: an Italian multicenter study

2012; De Gruyter; Volume: 50; Issue: 4 Linguagem: Inglês

10.1515/cclm.2011.823

1437-4331

Fabio Manoni, Gianluca Gessoni, Maria Grazia Alessio, Alberta Caleffi, Graziella Saccani, M. Silvestri, Donatella Poz, Mauro Ercolin, Agostino Tinello, Sara Valverde, Cosimo Ottomano, Giuseppe Lippi,

Colorectal Cancer Screening and Detection

In analogy with other areas of laboratory diagnostics, the pre-analytical phase is the leading source of variability also in urinalysis. We carried out a multicentric study for comparing results obtained from first-voided and mid-stream urine samples.Each of the six hospital-based clinical laboratories participating to this study recruited 50 healthy subjects among laboratory staff and/or their relatives. Two consecutive samples of the first morning micturition were collected by vacuum system, the first from the first-void and the second from the mid-stream. Routine urinalysis was performed using dip-stick automated analyzers for chemical examination and automated analyzers for formed particle examination (Sysmex UF-100, Sysmex UF-1000i and Iris iQ-200).Counts of epithelial cells (EC), erythrocytes (ERY) and leukocytes (LEU) but not for cylinders (CAS) were significantly higher in the first-voided samples. A significantly higher count of EC, ERY and LEU was also observed between females and males in first-voided samples, whereas no significant difference could be found in mid-stream samples. Health related analyzer specific upper reference limits (URL) were CAS≤1, EC≤5, ERY≤19, Leu≤13 for UF-100; CAS≤1, EC≤4, ERY≤15, Leu≤11 for UF-1000i; CAS≤1, EC≤4, ERY≤18, Leu≤10 for iQ200. The overall prevalence of subjects with cellular elements count exceeding URL was also higher in first-voided than in mid-stream samples.Mid-stream urine was confirmed as the most appropriate sample, since the presence of contaminating elements, such as bacteria, analytes and formed particles are minimized.