title: Sensitive noninvasive marker for the diagnosis of probable bacterial or viral infection.
abstract: Urinary trypsin inhibitor (uTi) is a product of elastase-mediated degradation of interleukin-alpha-inhibitor (I-alpha-I). Its activity increases in the urine of patients with a malignancy, inflammation, or infection, or in late pregnancy. The objective of this study was to compare the sensitivity of uTi in urine with that of serum quantitative C-reactive protein (CRP) for diagnosing infection, as indicated by white cell response and clinical assessment. Ninety controls and 171 patients with various systemic infections were enrolled. We measured uTi enzymatically on a Cobas Fara (Roche Diagnostics). Patients were separated into bacterial, probable bacterial, viral, or probable viral groups based on the results of a complete blood count with differential (CBC), urinalysis (UA), and clinical assessment. In the bacterial (n=70) and control (n=90) groups, the uTi values (mean+/-SE) were 25.3+/-3.1 mg/L and 2.8+/-0.8 mg/L, respectively. uTi (at 2.7 mg/L) had a diagnostic sensitivity of 91% and specificity of 82% (AUC=0.889), whereas CRP (at a cutoff of 10 mg/L) had a sensitivity and specificity of 82% and 96%, respectively (AUC=0.921). As a marker of infection (positive in both bacterial and viral groups), uTi had a sensitivity of 91% (AUC=0.884) vs. 89% (AUC=0.828) for CRP. Our data indicate that uTi has sufficient clinical sensitivity for screening systemic infections, and may have diagnostic value as a noninvasive test.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Louisville School of Medicine, Louisville, KY 40292, USA. sjortani@louisville.edu
authors.forename: Saeed A
authors.initials: SA
authors.lastname: Jortani
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pugia
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Elin
authors.forename: Meera
authors.initials: M
authors.lastname: Thomas
authors.forename: Edward P
authors.initials: EP
authors.lastname: Womack
authors.forename: Todd
authors.initials: T
authors.lastname: Cast
authors.forename: Roland
authors.initials: R
authors.lastname: Valdes
mesh_terms: D000328:Adult; D001424:Bacterial Infections / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002097:C-Reactive Protein / Q000032:analysis; D003401:Creatine / Q000652:urine; D006023:Glycoproteins / Q000652:urine*; D006801:Humans; D007958:Leukocyte Count; D008875:Middle Aged; D012372:ROC Curve; D014777:Virus Diseases / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D006023:Glycoproteins; D002097:C-Reactive Protein; D003401:Creatine; C028665:urinastatin