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Serum and urinary thioredoxin concentrations are associated with severity of children hydronephrosis
Clinica Chimica Acta 466 (2017) 127–132
Contents lists available at ScienceDirect
Clinica Chimica Acta journal homepage: www.elsevier.com/locate/clinchim
Serum and urinary thioredoxin concentrations are associated with severity of children hydronephrosis Zhe-Ming Xu, Min-Ju Li, Chang Tao ⁎ Department of Urology, The Children's Hospital, College of Medicine, Zhejiang University, 57 Zhugan Lane, Hangzhou 310003, China
a r t i c l e
i n f o
Article history: Received 25 November 2016 Received in revised form 14 January 2017 Accepted 18 January 2017 Available online 19 January 2017 Keywords: Thioredoxin Ureteropelvic junction obstruction Children Hydronephrosis
a b s t r a c t Background: Ureteropelvic junction obstruction (UPJO) is the most common cause of hydronephrosis in children. This study was to assess the relationship between serum thioredoxin (S-Trx) and urinary thioredoxin (U-Trx) concentrations and severity of children hydronephrosis caused by UPJO. Methods: This study included 156 hydronephrosis children with unilateral UPJO and 80 healthy children. S-Trx and U-Trx concentrations were measured using enzyme-linked immunosorbent assay. U-Trx/creatinine (cr) ratio was calculated. Results: S-Trx and U-Trx concentrations and U-Trx/cr ratio were significantly higher in hydronephrosis children than in healthy children. They were significantly correlated with split renal function, anterior–posterior diameter and Society for Fetal Urology classification, as well as were independently related to the split renal function b 39.2%, anterior–posterior diameter N 30 mm and Society for Fetal Urology grade IV. Under receiver operating characteristic curves, U-Trx/cr ratio showed the higher predictive value compared to S-Trx and U-Trx concentrations. Conclusion: Increased S-Trx and U-Trx concentrations, especially U-Trx/cr ratio, are closely associated with the severity of children hydronephrosis, substantializing Trx as a promising biomarker for the progression of children hydronephrosis. © 2017 Elsevier B.V. All rights reserved.
1. Introduction Congenital hydronephrosis (HN) is characterized by distension and dilation of the renal pelvis and calyces due to various congenital obstructive malformations of the kidneys and urinary tract. Ureteropelvic junction obstruction (UPJO) is the most common cause of congenital HN in children [1–3]. HN can evolve into renal agenesis and clinically presents as chronic kidney disease in children [4–6]. Currently, some clinical tests, including renal ultrasonography and radionuclide renography can help to predict the future course of HN and identify patients who require surgical treatment [7–9]. However, these conventional imaging modalities still are insufficient for decision making in managing the condition. In addition, radionuclide renography exposes children to
Abbreviations: Cr, creatinine; Trx, thioredoxin; S-Trx, serum Trx; U-Trx, urinary Trx; HN, hydronephrosis; UPJO, ureteropelvic junction obstruction; eGFR, estimated glomerular filtration rate; APD, anterior–posterior diameter; SRF, split renal function; SFU, Society for Fetal Urology. ⁎ Corresponding author. E-mail address: [email protected] (C. Tao).
http://dx.doi.org/10.1016/j.cca.2017.01.020 0009-8981/© 2017 Elsevier B.V. All rights reserved.
radiation and causes radiation damage. Thus, the interests of clinicians have focused on the potential role of plasma or urine markers in HN [10–12]. HN-caused renal injury is a complex process and its underlying mechanisms involve oxidative stress and inflammation [13–15]. Thioredoxin (Trx), a 12-kDa ubiquitous thiol protein, possesses a potent anti-oxidant effect and modulates inflammation [16–19]. Intracellular Trx is released from cells upon oxidative stress, leading to high extracellular concentrations in a great number of critical illnesses including: severe burn injury, chronic heart failure, acute live injury and sepsis [20–23]. Recently, increased serum Trx concentrations are found to be a diagnostic marker for hepatocellular carcinoma [24], and have close relation with myocardial damage amount in acute myocardial infarction [25]. Moreover, enhanced serum TRX concentrations are correlated significantly with the severity and poor outcome following acute ischemic stroke [26], severe traumatic brain injury [27] and intracerebral hemorrhage [28]. Recently, Trx is found to be increased in urine from mice with acute nephropathy, in which it exerts a protective effect on injured kidney [29,30]. This study was designed to investigate serum Trx (STrx) and U-Trx concentrations in children with UPJO-caused HN and further elucidate the relationship between its concentrations and the HN severity.
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Fig. 1. Intergroup comparisons of serum thioredoxin (S-Trx) and urinary thioredoxin (U-Trx) concentrations as well as U-Trx/creatinine (cr) ratio between controls and hydronephrosis children.
Table 1 Correlative analysis between thioredoxin levels and split renal function and anterior-posterior diameter in hydronephrosis children. Parameter
S-Trx levels Model 1 Model 2 U-Trx levels Model 1 Model 2 U-Trx/cr ratio Model 1 Model 2
Split renal function
Anterior–posterior diameter
r value
P value
r value
P value
−0.235 −0.209
0.003 0.010
0.200 0.169
0.012 0.037
−0.417 −0.300
b0.001 b0.001
0.345 0.292
b0.001 b0.001
−0.503 −0.437
b0.001 b0.001
0.453 0.337
b0.001 b0.001
In model 1, bivariate correlation analyses were conducted using Spearman”s correlation coefficient. In model 2, partial correlation coefficient was performed for adjustment of age, sex and estimated glomerular filtration rate. S-Trx indicates serum thioredoxin; UTrx, urinary thioredoxin; cr, creatinine.
2. Materials and methods 2.1. Study population This was a cross-sectional study carried out between January 2011 and January 2015 at the Children's Hospital, College of Medicine, Zhejiang University, China. We included the children with HN due to unilateral UPJO. We excluded those children with urinary tract infection, vesicoureteral reflux, ureterovesical junction obstruction, posterior urethral valve obstruction, bilateral HN, previous operation on the urinary system, other deformations of the external genital organs, lower urinary tract anomalies, urinary stones and neurogenic bladder dysfunction. The control group was composed of healthy children referred to a pediatric outpatient clinic, where all children are periodically monitored for their development and growth. This study was approved by the ethics committee of our medical faculty. All caregivers of the children were interviewed and gave written informed consent for the children to participate in the study.
Table 2 Independent association of thioredoxin levels with the children hydronephrosis severity. Parameter
S-Trx levels Model 1 Model 2 U-Trx levels Model 1 Model 2 U-Trx/cr ratio Model 1 Model 2
Split renal function b39.2%
Anterior–posterior diameter N 30 mm
Society for Fetal Urology grade IV
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
1.063 (1.026–1.102) 1.067 (1.029–1.107)
0.001 0.001
1.034 (1.001–1.069) 1.037 (1.004–1.074)
0.042 0.040
1.035 (1.002–1.069) 1.038 (1.007–1.093)
0.035 0.030
1.108 (1.066–1.152) 1.104 (1.060–1.148)
b0.001 b0.001
1.071 (1.037–1.106) 1.082 (1.047–1.117)
b0.001 b0.001
1.072 (1.039–1.106) 1.085 (1.051–1.130)
b0.001 b0.001
1.172 (1.112–1.236) 1.181 (1.119–1.245)
b0.001 b0.001
1.126 (1.080–1.175) 1.133 (1.086–1.189)
b0.001 b0.001
1.099 (1.062–1.138) 1.102 (1.073–1.159)
b0.001 b0.001
Using binary logistic regression analysis, model 1 only included thioredoxin levels as independent variable and model 2 entered thioredoxin levels in addition to age, sex and estimated glomerular filtration rate as independent variables. S-Trx indicates serum thioredoxin; U-Trx, urinary thioredoxin; cr, creatinine.
Z.-M. Xu et al. / Clinica Chimica Acta 466 (2017) 127–132
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Table 3 Discriminatory role of thioredoxin levels for the poor children hydronephrosis severity. Parameter
U-Trx/cr ratio U-Trx levels S-Trx levels
Split renal function b39.2%
Anterior–posterior diameter N 30 mm
Society for Fetal Urology grade IV
AUC (95% CI)
P value
AUC (95% CI)
P value
AUC (95% CI)
P value
0.869 (0.805–0.917) 0.789 (0.716–0.850) 0.684 (0.605–0.756)
Ref. 0.014 b0.001
0.831 (0.763–0.887) 0.742 (0.666–0.809) 0.630 (0.549–0.705)
Ref. 0.006 b0.001
0.809 (0.739–0.868) 0.725 (0.648–0.793) 0.609 (0.528–0.686)
Ref. 0.018 b0.001
Under receiver operating characteristic curves, intergroup comparisons were done using Z test. S-Trx indicates serum thioredoxin; U-Trx, urinary thioredoxin; cr, creatinine; AUC.
2.2. Assessment Recorded information included age, sex, laterality, HN grade, anterior–posterior diameter (APD), glomerular filtration rate estimated by the Schwartz formula (eGFR) and split renal function (SRF). A technetium-99 m diethylenetriamine pentaacetic acid diuretic renography was used to evaluate SRF. The HN degree was graded according to the Society for Fetal Urology (SFU) classification: grade I represents a split pelvis; grade II is further dilation of the renal pelvis, with a few visualized calyces permissible; grade III is renal pelvis dilation, with many distended calyces; and grade IV is a grade III appearance with the addition of thinned parenchyma [31]. SFU classification, APD and SRF were used to assess the severity of children unilateral HN.
2.3. Determination Blood samples and voided urine were collected in the morning from healthy children and HN children. Using a commercial enzyme-linked immunosorbent assay kit for human Trx (Redox Bioscience, Kyoto,
Japan), S-Trx and U-Trx were determined in duplicate by the same technician who had no access to clinical information. The urinary creatinine (cr) concentration was used to normalize U-Trx measurements to account for the influence of urinary dilution on its concentration. U-Trx concentrations were expressed as U-Trx/cr ratio in ng/mg cr.
2.4. Statistical analysis SPSS 19.0 and MedCalc 9.6.4.0 (MedCalc Software) were used for statistical analyses. Categorical variables were reported as counts (percentage). All continuous variables were not normally distributed, and therefore were presented as median (interquartile range). Comparisons were made by using chi-square test or Fisher exact test for categorical data and the Mann–Whitney U test for continuous non-normally distributed variables. Bivariate correlation analyses were conducted using Spearman's correlation coefficient. Partial correlation coefficient was performed for correction of age, sex and eGFR. APD and SRF were identified as categorical variables based on their median values. Binary logistic regression analyses were performed to investigate the independent
Fig. 2. Receiver operating characteristic curves of serum thioredoxin levels for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
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association of TRX concentrations with SFU classification, APD and SRF by correction of age, sex and eGFR. Subsequently, odds ratio (OR) and the corresponding 95% confidence interval (CI) were estimated. Receiver operating characteristic (ROC) curves were performed to evaluate discriminatory ability. And then, area under curve (AUC) and the corresponding 95% CI were calculated. Initially, a P b 0.05 was considered to be statistically significant.
3. Results 3.1. Study population characteristics This study enrolled 156 HN children with unilateral UPJO and 80 healthy children. HN children had a median age of 2.2 (4.5) y and consisted of 94 males and 62 females. Healthy children with a median age of 2.5 (5.7) y, were composed of 45 males and 35 females. There were not statistically significant intergroup differences in the age and sex. In addition, a total of 98 left kidneys and 58 right kidneys were involved in the HN children. There were 88 children with SFU grade III and 68 with grade IV. The median APD, SRF and eGFR were 30.0 (28.8) mm, 39.2 (11.5) % and 139.8 (50.8) ml/min/1.73 m2 respectively.
3.2. Change of Trx concentrations In Fig. 1, compared with the controls, S-Trx and U-Trx concentrations and U-Trx/cr ratio were significantly increased in HN children. In Table 1, S-Trx and U-Trx concentrations and U-Trx/cr ratio were highly correlated with APD and SRF. Even, after adjustment of age, sex and eGFR, these correlations still appeared statistically significant.
3.3. Relationship between Trx concentrations and HN severity SRF and APD were bifurcated based on their median values (39.2% and 30.0 mm respectively). In Table 2, univariate binary logistic regression analyses demonstrated that either S-Trx concentrations, U-Trx concentrations or U-Trx/cr ratio was highly associated with the HN severity reflected by SRF b 39.2%, APD N 30 mm and SFU grade IV; moreover, when age, sex and eGFR were considered as the confounding variables, S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio still had close relation to the HN severity. Just shown in Table 3, S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio significantly discriminated SRF b 39.2%, APD N 30 mm or SFU grade IV under ROC curves; also, U-Trx/cr ratio showed the higher distinguishing ability than S-Trx and U-Trx concentrations; additionally, in Figs. 2–4, an optimal value of S-Trx concentrations, U-Trx concentrations or U-Trx/cr ratio was chosen, which predicted SRF b 39.2%, APD N 30 mm or SFU grade IV with the medium or high sensitivity and specificity. 4. Discussion This study focused on the assessment of relationship between S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio and the severity of children HN caused by unilateral UPJO, which were reflected by SRF, APD and SFU classification. Subsequently, we found that (1) S-Trx and U-Trx concentrations and U-Trx/cr ratio in HN children were significantly increased, were highly correlated with APD and SRF, and were independently associated with the SRF b 39.2%, APD N 30 mm and SFU grade IV; (2) U-Trx/cr ratio showed higher AUCs in discriminating SRF b 39.2%, APD N 30 mm and SFU grade IV compared to S-Trx and U-Trx concentrations. These data indicate that increased S-Trx and U-
Fig. 3. Receiver operating characteristic curves of urinary thioredoxin levels for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
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Fig. 4. Receiver operating characteristic curves of urinary thioredoxin/creatinine ratio for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
Trx concentrations, especially increased U-Trx/cr ratio, might closely be associated with the severity of children HN. Trx, a potent anti-oxidant, regulates inflammation, cell growth and apoptosis, and can be released during oxidative stress and inflammation [16–19]. Circulating Trx concentrations are increased in sepsis, postcardiac arrest syndrome, acute myocardial infarction and malignant neoplasms, in which Trx has close relation to the severity and prognosis [20–28]. In the kidney, Trx is retained in medullary thick ascending limb and secreted from proximal tubuli into urine during renal ischemia/reperfusion, as well as exerts its protective effect [29]. High concentrations of urinary Trx (U-Trx) are reported in animals with ischaemic renal diseases and in patients with acute renal injury, suggesting U-Trx as a potent renal biomarker of oxidative injury [30]. Thus, in the current study, the increased Trx concentrations in HN children might reflect renal injury caused by HN. In this study, SRF, APD and SFU grade were chosen to reflect the severity of children HN. SRF and APD were identified as the continuous or categorical variable. We found that S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio were independently associated with SRF, APD and SFU grade, indicating Trx concentrations might reflect the severity of children HN. Importantly, ROC curves demonstrated that they discriminated the SRF, APD and SFU grade with large AUCs. Interestingly, we found that, compared to S-Trx concentrations and U-Trx concentrations, U-Trx/cr ratio showed the larger AUCs, suggesting that Trx in serum or urine, especially U-Trx/cr ratio, could be a promising biomarker for the children HN progression. In this ELISA study, because the values of U-Trx are preliminarily proved to be stable at physiological pHs (pH 5–8), and not to be
influenced by the temperature (freeze/thaw) and a presence of cellular components in urine, this ELISA system is suitable for use with clinical urine samples [30] However, because all children included in this study are Chinese, the results may not be more generally applicable to populations of other ethnic origins. Clearly, a multicenter clinical trial is required to validate these results. 5. Conclusions Increased S-Trx and U-Trx concentrations, especially increased UTrx/cr ratio, are closely associated with the severity of children HN, which were reflected by SRF, APD and SFU classification. Thus, Trx might be a promising biomarker for the children HN progression. Acknowledgements The authors thank Professor Zhe-Ming Wang in BSAZ Biotech Co., Ltd (Hangzhou, China) for their technical support. References [1] R.L. Chevalier, B.A. Thornhill, M.S. Forbes, S.C. Kiley, Mechanisms of renal injury and progression of renal disease in congenital obstructive nephropathy, Pediatr. Nephrol. 25 (2010) 687–697. [2] P.L. Zhang, C.A. Peters, S. Rosen, Ureteropelvic junction obstruction: morphological and clinical studies, Pediatr. Nephrol. 14 (2000) 820–826. [3] C.S. Dias, J.M. Silva, A.K. Pereira, V.S. Marino, L.A. Silva, A.M. Coelho, et al., Diagnostic accuracy of renal pelvic dilatation for detecting surgically managed ureteropelvic junction obstruction, J. Urol. 190 (2013) 661–666. [4] B. Aoun, T. Ulinski, S. Termos, G. Kalkas, H. Fakhoury, C.P. Schmitt, Rapid and sustained recovery of renal function with transient placement of an intrauretral
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Contents lists available at ScienceDirect
Clinica Chimica Acta journal homepage: www.elsevier.com/locate/clinchim
Serum and urinary thioredoxin concentrations are associated with severity of children hydronephrosis Zhe-Ming Xu, Min-Ju Li, Chang Tao ⁎ Department of Urology, The Children's Hospital, College of Medicine, Zhejiang University, 57 Zhugan Lane, Hangzhou 310003, China
a r t i c l e
i n f o
Article history: Received 25 November 2016 Received in revised form 14 January 2017 Accepted 18 January 2017 Available online 19 January 2017 Keywords: Thioredoxin Ureteropelvic junction obstruction Children Hydronephrosis
a b s t r a c t Background: Ureteropelvic junction obstruction (UPJO) is the most common cause of hydronephrosis in children. This study was to assess the relationship between serum thioredoxin (S-Trx) and urinary thioredoxin (U-Trx) concentrations and severity of children hydronephrosis caused by UPJO. Methods: This study included 156 hydronephrosis children with unilateral UPJO and 80 healthy children. S-Trx and U-Trx concentrations were measured using enzyme-linked immunosorbent assay. U-Trx/creatinine (cr) ratio was calculated. Results: S-Trx and U-Trx concentrations and U-Trx/cr ratio were significantly higher in hydronephrosis children than in healthy children. They were significantly correlated with split renal function, anterior–posterior diameter and Society for Fetal Urology classification, as well as were independently related to the split renal function b 39.2%, anterior–posterior diameter N 30 mm and Society for Fetal Urology grade IV. Under receiver operating characteristic curves, U-Trx/cr ratio showed the higher predictive value compared to S-Trx and U-Trx concentrations. Conclusion: Increased S-Trx and U-Trx concentrations, especially U-Trx/cr ratio, are closely associated with the severity of children hydronephrosis, substantializing Trx as a promising biomarker for the progression of children hydronephrosis. © 2017 Elsevier B.V. All rights reserved.
1. Introduction Congenital hydronephrosis (HN) is characterized by distension and dilation of the renal pelvis and calyces due to various congenital obstructive malformations of the kidneys and urinary tract. Ureteropelvic junction obstruction (UPJO) is the most common cause of congenital HN in children [1–3]. HN can evolve into renal agenesis and clinically presents as chronic kidney disease in children [4–6]. Currently, some clinical tests, including renal ultrasonography and radionuclide renography can help to predict the future course of HN and identify patients who require surgical treatment [7–9]. However, these conventional imaging modalities still are insufficient for decision making in managing the condition. In addition, radionuclide renography exposes children to
Abbreviations: Cr, creatinine; Trx, thioredoxin; S-Trx, serum Trx; U-Trx, urinary Trx; HN, hydronephrosis; UPJO, ureteropelvic junction obstruction; eGFR, estimated glomerular filtration rate; APD, anterior–posterior diameter; SRF, split renal function; SFU, Society for Fetal Urology. ⁎ Corresponding author. E-mail address: [email protected] (C. Tao).
http://dx.doi.org/10.1016/j.cca.2017.01.020 0009-8981/© 2017 Elsevier B.V. All rights reserved.
radiation and causes radiation damage. Thus, the interests of clinicians have focused on the potential role of plasma or urine markers in HN [10–12]. HN-caused renal injury is a complex process and its underlying mechanisms involve oxidative stress and inflammation [13–15]. Thioredoxin (Trx), a 12-kDa ubiquitous thiol protein, possesses a potent anti-oxidant effect and modulates inflammation [16–19]. Intracellular Trx is released from cells upon oxidative stress, leading to high extracellular concentrations in a great number of critical illnesses including: severe burn injury, chronic heart failure, acute live injury and sepsis [20–23]. Recently, increased serum Trx concentrations are found to be a diagnostic marker for hepatocellular carcinoma [24], and have close relation with myocardial damage amount in acute myocardial infarction [25]. Moreover, enhanced serum TRX concentrations are correlated significantly with the severity and poor outcome following acute ischemic stroke [26], severe traumatic brain injury [27] and intracerebral hemorrhage [28]. Recently, Trx is found to be increased in urine from mice with acute nephropathy, in which it exerts a protective effect on injured kidney [29,30]. This study was designed to investigate serum Trx (STrx) and U-Trx concentrations in children with UPJO-caused HN and further elucidate the relationship between its concentrations and the HN severity.
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Z.-M. Xu et al. / Clinica Chimica Acta 466 (2017) 127–132
Fig. 1. Intergroup comparisons of serum thioredoxin (S-Trx) and urinary thioredoxin (U-Trx) concentrations as well as U-Trx/creatinine (cr) ratio between controls and hydronephrosis children.
Table 1 Correlative analysis between thioredoxin levels and split renal function and anterior-posterior diameter in hydronephrosis children. Parameter
S-Trx levels Model 1 Model 2 U-Trx levels Model 1 Model 2 U-Trx/cr ratio Model 1 Model 2
Split renal function
Anterior–posterior diameter
r value
P value
r value
P value
−0.235 −0.209
0.003 0.010
0.200 0.169
0.012 0.037
−0.417 −0.300
b0.001 b0.001
0.345 0.292
b0.001 b0.001
−0.503 −0.437
b0.001 b0.001
0.453 0.337
b0.001 b0.001
In model 1, bivariate correlation analyses were conducted using Spearman”s correlation coefficient. In model 2, partial correlation coefficient was performed for adjustment of age, sex and estimated glomerular filtration rate. S-Trx indicates serum thioredoxin; UTrx, urinary thioredoxin; cr, creatinine.
2. Materials and methods 2.1. Study population This was a cross-sectional study carried out between January 2011 and January 2015 at the Children's Hospital, College of Medicine, Zhejiang University, China. We included the children with HN due to unilateral UPJO. We excluded those children with urinary tract infection, vesicoureteral reflux, ureterovesical junction obstruction, posterior urethral valve obstruction, bilateral HN, previous operation on the urinary system, other deformations of the external genital organs, lower urinary tract anomalies, urinary stones and neurogenic bladder dysfunction. The control group was composed of healthy children referred to a pediatric outpatient clinic, where all children are periodically monitored for their development and growth. This study was approved by the ethics committee of our medical faculty. All caregivers of the children were interviewed and gave written informed consent for the children to participate in the study.
Table 2 Independent association of thioredoxin levels with the children hydronephrosis severity. Parameter
S-Trx levels Model 1 Model 2 U-Trx levels Model 1 Model 2 U-Trx/cr ratio Model 1 Model 2
Split renal function b39.2%
Anterior–posterior diameter N 30 mm
Society for Fetal Urology grade IV
OR (95% CI)
P value
OR (95% CI)
P value
OR (95% CI)
P value
1.063 (1.026–1.102) 1.067 (1.029–1.107)
0.001 0.001
1.034 (1.001–1.069) 1.037 (1.004–1.074)
0.042 0.040
1.035 (1.002–1.069) 1.038 (1.007–1.093)
0.035 0.030
1.108 (1.066–1.152) 1.104 (1.060–1.148)
b0.001 b0.001
1.071 (1.037–1.106) 1.082 (1.047–1.117)
b0.001 b0.001
1.072 (1.039–1.106) 1.085 (1.051–1.130)
b0.001 b0.001
1.172 (1.112–1.236) 1.181 (1.119–1.245)
b0.001 b0.001
1.126 (1.080–1.175) 1.133 (1.086–1.189)
b0.001 b0.001
1.099 (1.062–1.138) 1.102 (1.073–1.159)
b0.001 b0.001
Using binary logistic regression analysis, model 1 only included thioredoxin levels as independent variable and model 2 entered thioredoxin levels in addition to age, sex and estimated glomerular filtration rate as independent variables. S-Trx indicates serum thioredoxin; U-Trx, urinary thioredoxin; cr, creatinine.
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Table 3 Discriminatory role of thioredoxin levels for the poor children hydronephrosis severity. Parameter
U-Trx/cr ratio U-Trx levels S-Trx levels
Split renal function b39.2%
Anterior–posterior diameter N 30 mm
Society for Fetal Urology grade IV
AUC (95% CI)
P value
AUC (95% CI)
P value
AUC (95% CI)
P value
0.869 (0.805–0.917) 0.789 (0.716–0.850) 0.684 (0.605–0.756)
Ref. 0.014 b0.001
0.831 (0.763–0.887) 0.742 (0.666–0.809) 0.630 (0.549–0.705)
Ref. 0.006 b0.001
0.809 (0.739–0.868) 0.725 (0.648–0.793) 0.609 (0.528–0.686)
Ref. 0.018 b0.001
Under receiver operating characteristic curves, intergroup comparisons were done using Z test. S-Trx indicates serum thioredoxin; U-Trx, urinary thioredoxin; cr, creatinine; AUC.
2.2. Assessment Recorded information included age, sex, laterality, HN grade, anterior–posterior diameter (APD), glomerular filtration rate estimated by the Schwartz formula (eGFR) and split renal function (SRF). A technetium-99 m diethylenetriamine pentaacetic acid diuretic renography was used to evaluate SRF. The HN degree was graded according to the Society for Fetal Urology (SFU) classification: grade I represents a split pelvis; grade II is further dilation of the renal pelvis, with a few visualized calyces permissible; grade III is renal pelvis dilation, with many distended calyces; and grade IV is a grade III appearance with the addition of thinned parenchyma [31]. SFU classification, APD and SRF were used to assess the severity of children unilateral HN.
2.3. Determination Blood samples and voided urine were collected in the morning from healthy children and HN children. Using a commercial enzyme-linked immunosorbent assay kit for human Trx (Redox Bioscience, Kyoto,
Japan), S-Trx and U-Trx were determined in duplicate by the same technician who had no access to clinical information. The urinary creatinine (cr) concentration was used to normalize U-Trx measurements to account for the influence of urinary dilution on its concentration. U-Trx concentrations were expressed as U-Trx/cr ratio in ng/mg cr.
2.4. Statistical analysis SPSS 19.0 and MedCalc 9.6.4.0 (MedCalc Software) were used for statistical analyses. Categorical variables were reported as counts (percentage). All continuous variables were not normally distributed, and therefore were presented as median (interquartile range). Comparisons were made by using chi-square test or Fisher exact test for categorical data and the Mann–Whitney U test for continuous non-normally distributed variables. Bivariate correlation analyses were conducted using Spearman's correlation coefficient. Partial correlation coefficient was performed for correction of age, sex and eGFR. APD and SRF were identified as categorical variables based on their median values. Binary logistic regression analyses were performed to investigate the independent
Fig. 2. Receiver operating characteristic curves of serum thioredoxin levels for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
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association of TRX concentrations with SFU classification, APD and SRF by correction of age, sex and eGFR. Subsequently, odds ratio (OR) and the corresponding 95% confidence interval (CI) were estimated. Receiver operating characteristic (ROC) curves were performed to evaluate discriminatory ability. And then, area under curve (AUC) and the corresponding 95% CI were calculated. Initially, a P b 0.05 was considered to be statistically significant.
3. Results 3.1. Study population characteristics This study enrolled 156 HN children with unilateral UPJO and 80 healthy children. HN children had a median age of 2.2 (4.5) y and consisted of 94 males and 62 females. Healthy children with a median age of 2.5 (5.7) y, were composed of 45 males and 35 females. There were not statistically significant intergroup differences in the age and sex. In addition, a total of 98 left kidneys and 58 right kidneys were involved in the HN children. There were 88 children with SFU grade III and 68 with grade IV. The median APD, SRF and eGFR were 30.0 (28.8) mm, 39.2 (11.5) % and 139.8 (50.8) ml/min/1.73 m2 respectively.
3.2. Change of Trx concentrations In Fig. 1, compared with the controls, S-Trx and U-Trx concentrations and U-Trx/cr ratio were significantly increased in HN children. In Table 1, S-Trx and U-Trx concentrations and U-Trx/cr ratio were highly correlated with APD and SRF. Even, after adjustment of age, sex and eGFR, these correlations still appeared statistically significant.
3.3. Relationship between Trx concentrations and HN severity SRF and APD were bifurcated based on their median values (39.2% and 30.0 mm respectively). In Table 2, univariate binary logistic regression analyses demonstrated that either S-Trx concentrations, U-Trx concentrations or U-Trx/cr ratio was highly associated with the HN severity reflected by SRF b 39.2%, APD N 30 mm and SFU grade IV; moreover, when age, sex and eGFR were considered as the confounding variables, S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio still had close relation to the HN severity. Just shown in Table 3, S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio significantly discriminated SRF b 39.2%, APD N 30 mm or SFU grade IV under ROC curves; also, U-Trx/cr ratio showed the higher distinguishing ability than S-Trx and U-Trx concentrations; additionally, in Figs. 2–4, an optimal value of S-Trx concentrations, U-Trx concentrations or U-Trx/cr ratio was chosen, which predicted SRF b 39.2%, APD N 30 mm or SFU grade IV with the medium or high sensitivity and specificity. 4. Discussion This study focused on the assessment of relationship between S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio and the severity of children HN caused by unilateral UPJO, which were reflected by SRF, APD and SFU classification. Subsequently, we found that (1) S-Trx and U-Trx concentrations and U-Trx/cr ratio in HN children were significantly increased, were highly correlated with APD and SRF, and were independently associated with the SRF b 39.2%, APD N 30 mm and SFU grade IV; (2) U-Trx/cr ratio showed higher AUCs in discriminating SRF b 39.2%, APD N 30 mm and SFU grade IV compared to S-Trx and U-Trx concentrations. These data indicate that increased S-Trx and U-
Fig. 3. Receiver operating characteristic curves of urinary thioredoxin levels for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
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Fig. 4. Receiver operating characteristic curves of urinary thioredoxin/creatinine ratio for discriminating split renal function b39.2% (A), anterior–posterior diameter N 30 mm (B) and Society for Fetal Urology grade IV (C) in hydronephrosis children.
Trx concentrations, especially increased U-Trx/cr ratio, might closely be associated with the severity of children HN. Trx, a potent anti-oxidant, regulates inflammation, cell growth and apoptosis, and can be released during oxidative stress and inflammation [16–19]. Circulating Trx concentrations are increased in sepsis, postcardiac arrest syndrome, acute myocardial infarction and malignant neoplasms, in which Trx has close relation to the severity and prognosis [20–28]. In the kidney, Trx is retained in medullary thick ascending limb and secreted from proximal tubuli into urine during renal ischemia/reperfusion, as well as exerts its protective effect [29]. High concentrations of urinary Trx (U-Trx) are reported in animals with ischaemic renal diseases and in patients with acute renal injury, suggesting U-Trx as a potent renal biomarker of oxidative injury [30]. Thus, in the current study, the increased Trx concentrations in HN children might reflect renal injury caused by HN. In this study, SRF, APD and SFU grade were chosen to reflect the severity of children HN. SRF and APD were identified as the continuous or categorical variable. We found that S-Trx concentrations, U-Trx concentrations and U-Trx/cr ratio were independently associated with SRF, APD and SFU grade, indicating Trx concentrations might reflect the severity of children HN. Importantly, ROC curves demonstrated that they discriminated the SRF, APD and SFU grade with large AUCs. Interestingly, we found that, compared to S-Trx concentrations and U-Trx concentrations, U-Trx/cr ratio showed the larger AUCs, suggesting that Trx in serum or urine, especially U-Trx/cr ratio, could be a promising biomarker for the children HN progression. In this ELISA study, because the values of U-Trx are preliminarily proved to be stable at physiological pHs (pH 5–8), and not to be
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