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The following is a summary of “Plasma procalcitonin and urine interleukin-8, Neutrophil Gelatinase-Associated Lipocalin, and calprotectin in the diagnostic process of a urinary tract infection at the emergency department,” published in the October 2024 issue of Infectious Disease by Middelkoop et al. 

Researchers conducted a retrospective study to assess the diagnostic utility of plasma procalcitonin and urine interleukin-8 (IL-8), Neutrophil Gelatinase-Associated Lipocalin (NGAL), and calprotectin for urinary tract infections (UTIs) in the emergency department (ED).    

They compared biomarker performance to routine diagnostics in adults presenting at the ED with UTI suspicion. Patients with a urine catheter, leukopenia, or neither (standard) were analyzed separately.   

The results showed that a UTI was clinically diagnosed in 91/196 episodes (46.4%). Standard: 29/67 (43.2%), catheter 46/73 (63.0%), leukopenia 17/60 (28.3%) (4 had both). Procalcitonin did not discriminate between UTI and without UTI. Urinary biomarker levels were elevated in UTI episodes (median, µg/mmol creatinine): NGAL 7.8 vs. 46.3, IL-8 6.1 vs. 76.6, calprotectin 23.9 vs. 265.4. All 3 subgroups also had higher levels. Biomarker cut-off values (90% sensitivity) showed low specificity (20.8%-64.9%) and moderate accuracy (58.6%-75.4%). Biomarkers performed similarly to routine diagnostics, except patients with leukopenia had slightly higher AUC values, while all urinary biomarkers correlated positively with urine leucocyte count.   

Investigators concluded that plasma procalcitonin was inaccurate for diagnosing UTIs, and urine IL-8, NGAL, and calprotectin offered no additional value over routine diagnostics except in patients with leucopenia primarily reflecting leukocyturia. 

Source: ijidonline.com/article/S1201-9712(24)00328-X/fulltext