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Abstract: PO0326

Increased Urinary Leukocyte Esterase Distinguishes Brushite Stone Formers from Patients with Other Stone Types

Session Information

Category: Bone and Mineral Metabolism

  • 401 Bone and Mineral Metabolism: Basic

Authors

  • Bergsland, Kristin J., University of Chicago, Chicago, Illinois, United States
  • Coe, Fredric L., University of Chicago, Chicago, Illinois, United States
  • Worcester, Elaine M., University of Chicago, Chicago, Illinois, United States
Background

Compared with calcium oxalate (CaOx) stone formers (SF), patients with brushite (Br) stones have elevated neutrophil infiltration in their renal papillae which may be associated with the observed marked increase in papillary scarring and inflammation. We investigated whether a signal of neutrophil elevation in the kidney could be detected in the urine when not associated with infection.

Methods

We performed urine dipstick analyses for leukocyte esterase (LEU), an enzyme produced by neutrophils, and various markers of infection including nitrite (NIT), blood (BLO) and protein (PRO). 24-hr urine specimens were tested using the Siemens Multistix 10SG dipstick read on a Clinitek Status analyzer. We measured urine ammonia on a Beckman DxC600. We retrospectively analyzed 812 urines from 215 patients; stone type of patients was determined by stone analysis containing >50% apatite (Ap), Br, CaOx or uric acid (UA), respectively. BLO, PRO and LEU measurements were on a 5 point scale (negative=0, trace=0.5, small=1, moderate=2, large=3); NIT was yes or no.

Results

In a fully adjusted ANOVA model by stone type and sex with LEU as the dependent variable and BLO, PRO, NIT, ammonia excretion and patient age as covariates, brushite SF had significantly higher LEU than CaOx or UA (Table). By Chi-square, NIT was not different between the stone types (p = 0.25). Ammonia excretion was not different between stone types. In an ANOVA of the mean LEU by patient adjusted for the number of stone removal procedures, LEU in Br SF was higher than in CaOx SF (p<0.01).

Conclusion

Dipstick LEU is informative in SF aside from predicting infection. Dipstick LEU was significantly higher in Br SF than in CaOx SF but NIT, indicating infection, was not different between stone types. Adjusting for other indicators of infection, such as ammonia, BLO, and PRO as well as the number of stone removal procedures did not abolish this difference. Dipstick LEU may serve as a urine biomarker of the inflammatory activity and neutrophil infiltration that we have observed in the kidneys of Br SF and may reflect the papillary histopathology.

Table. Dipstick LEU by Sex and Stone Type
 WomenMen
 ApBrCaOxUAApBrCaOxUA
LEU0.59±0.070.95±0.06*$0.40±0.060.23±0.100.35±0.060.57±0.06#+0.17±0.070.12±0.05

Mean±SE. *p<0.0001 vs CaOx or UA; $p<0.001 vs Ap; #p<0.0001 vs UA; +p<0.001 vs CaOx

Funding

  • NIDDK Support