INABILITY OF COMMUNITY-BASED LABORATORIES TO IDENTIFY PATHOLOGICAL CASTS IN URINE SAMPLES

Objective: To determine the accuracy of microscopic examination of uri ne from patients with known renal disease, performed by community-base d laboratories. Design: Twenty-six urine specimens from 7 children wit h Alport syndrome, lupus nephritis, and IgA nephropathy were simultane ously submitted to 4 investigative sites: 2 community-based medical la boratories (laboratories A and B), and the offices of 2 nephrologists (nephrologists C and D). Participants A, B, and C were unaware of the nature of this investigation and blinded to the diagnosis associated w ith each specimen. Results: Twenty-six specimens from 7 children were analyzed. Pathological casts were identified in the 26 submitted speci mens in the following order: 1 (4%) by laboratory A, 2 (8%) by laborat ory B, 20 (77%) by nephrologist C, and 26 (100%) by nephrologist D. Fo ur-way and 3-way (A, B, C) comparisons using the chi(2) test are signi ficant at the P<.001 level. Conclusions: The 2 community-based medical laboratories participating in this study did not accurately identify pathological casts in urine specimens routinely submitted to them. In addition to raising quality assurance issues, these misleading reports may result in inaccurate diagnosis and unnecessary laboratory and dia gnostic investigations.