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Updated: Oct 2, 2026

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples
Published on: May 21, 2021
Plasma and urine elastase alpha-1-proteinase inhibitor levels in neonatal urinary tract infection
P Bakakos1, A Messaritaki, H Mandyla
1Neonatal Unit, First Department of Pediatrics, Athens University, Athens, Greece.
Objective:
To examine whether plasma or urine elastase alpha(1)-proteinase inhibitor (E-alpha(1)-PI) levels could be used as a diagnostic marker of urinary tract infection (UTI) in neonates.
Subjects And Methods:
Plasma and urine E-alpha(1)-PI levels were measured by immunoassay in 23 neonates with UTI at the time of admission and 72 h after the onset of treatment and in 10 'normal' neonates (i.e. with trivial problems). Additionally E-alpha(1)-PI plasma levels were measured in 15 neonates with septicemia.
Results:
E-alpha(1)-PI plasma levels did not differ between normal neonates and those with UTI. Urine E-alpha(1)-PI levels were significantly higher in neonates with UTI on admission compared to normal neonates. A significant decrease in urine E-alpha(1)-PI levels was noticed 72 h after the onset of treatment in all but 2 neonates in whom infection persisted. In this study, we have found that the urine E-alpha(1)-PI concentration at a cutoff level of 48 microg/l had a sensitivity of 83%, a specificity of 90%, a positive predictive value of 95% and a negative predictive value of 69% for the diagnosis of neonatal UTI.
Conclusion:
Elevated levels of E-alpha(1)-PI in urine seem to be a useful tool for the diagnosis of UTI in neonates (even in those that have already been started on antibiotics) and possibly a valuable marker for early recognition of treatment failure.
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