title: Mid-stream vs. first-voided urine collection by using automated analyzers for particle examination in healthy subjects: an Italian multicenter study.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Servizio di Medicina di Laboratorio, Ospedali di Este e Monselice, Padova, Italy. fabio.manoni@ulss17.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Manoni
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gessoni
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Alessio
authors.forename: Alberta
authors.initials: A
authors.lastname: Caleffi
authors.forename: Graziella
authors.initials: G
authors.lastname: Saccani
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Silvestri
authors.forename: Donatella
authors.initials: D
authors.lastname: Poz
authors.forename: Mauro
authors.initials: M
authors.lastname: Ercolin
authors.forename: Agostino
authors.initials: A
authors.lastname: Tinello
authors.forename: Sara
authors.initials: S
authors.lastname: Valverde
authors.forename: Cosimo
authors.initials: C
authors.lastname: Ottomano
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001331:Automation; D005260:Female; D006262:Health; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D012995:Solubility; D016482:Urinalysis / Q000379:methods*; D014554:Urination; D059349:Urine Specimen Collection / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult