The Authors Reply: Relationship Between Spontaneous Passage Rates of Ureteral Stones Less Than 8 mm and Serum C-Reactive Protein Levels and Neutrophil Percentages

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. To the editor: I appreciate the comments of the author of the critique of " Relationship between spontaneous passage rates of ure-teral stones less than 8 mm and serum C-reactive protein levels and neutrophil percentages. " The purpose of our study was to assess the usefulness of C-reactive protein (CRP) and neutrophil percentages as an indicator of the spontaneous passage rates of ureteral stones that are less than 8 mm in size. CRP is a nonspecific acute phase reagent for which plasma levels are severely elevated in proportion to the in-flammatory stimulus. The normal concentration in healthy human serum is usually lower than 1 mg/dL and slightly increases with aging. Higher levels are found in pregnant women near the end of pregnancy, with mild inflammation and viral infections (1–4 mg/dL), and with active inflammation, bacterial infection (4–20 mg/dL), and severe bacterial infections and burns (＞20 mg/dL) [1]. Likewise, the normal range of CRP in our institution is also lower than 0.5 mg/dL. Angulo et al. [2] emphasized that the risk of early sepsis or occult sepsis is present if the CRP of the patients who have ureteric stones is elevated. In their study, the average CRP level of the diversion group was 13.9 mg/dL. In our study, however, the average CRP of the spontaneous passage group was 4.1 mg/dL and the average CRP of the no passage group was 8.3 mg/dL. The CRP levels of 90.3% of the patients (169 of 187 patients) were less than 5 mg/dL. Likewise, the stone sizes were smaller than those in Angulo et al. [2]'s study. In our study, we excluded patients who had acute or chronic infections. This shows that patients in our experiment had a lesser inflammatory state. Usually, the CRP level of the acute infection state is high. Chung et al. [3] studied the CRP level of patients who had acute uncomplicated pyelonephritis. The average CRP level of those pyelonephritis patients was 11.8 mg/dL. Paick et al. [4] studied the CRP level of patients with acute pyelonephritis. The initial mean CRP was 11.4 mg/dL. They categorized acute pyelonephritis into 4 grades according to renal parenchymal involvement. The CRP of the patients who did not …