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Original Article Hydronephrosis due to pelviureteric junction narrowing: Utility of urinary enzymes to predict the need for surgical management and follow-up Kirtikumar J. Rathod, Ram Samujh, Sumeet Agarwal, Ravi Prakash Kanojia, Ujjawal Sharma1, Rajendra Prasad1 Departments of Paediatric Surgery and 1Biochemistry, Post Graduate Institute of Medical Education and Research, Chandigarh, India Address for correspondence: Dr. Ram Samujh, Department of Paediatric Surgery, APC, Block 3-A, PGIMER, Sect 12, Chandigarh - 160 012, India. E-mail:
[email protected]
ABSTRACT Aim: To study the role of urinary enzymes N-acetyl--glucosaminidase (NAG), alkaline phosphatase (AKP) and gamma glutamyl transferase (GGT) in the diagnosis and follow-up of patients with suspected pelviureteric junction obstruction (PUJO). Materials and Methods: A total of 70 patients, 29 managed conservatively (group A) and 41 managed by pyeloplasty (group B), were studied prospectively. A serial measurement of urinary enzymes NAG, AKP and GGT level was performed in both the groups. The mean levels of these urinary enzymes were compared between the two groups and among the patients of the same group at presentation as well as during follow-up. Results: There was a significant fall in the mean AKP level in patients managed conservatively at 8 months of follow-up. Similarly, in the operated group, there was a significant fall in the AKP levels at both 3 months and 8 months of follow-up. The mean level of GGT also showed a significant fall after 3 months of surgery but did not show further significant change at 8 months after surgery. The mean levels of NAG and GGT in the conservatively managed group were significantly low compared with that of patients requiring pyeloplasty at presentation as well as in the follow-up. The mean level of AKP was significantly low in the conservatively managed group when compared with the patients requiring surgery, but did not differ significantly in both the followups after surgery. Conclusions: The level of urinary enzymes NAG, AKP and GGT are significantly high in the patients with hydronephrosis (HDN) requiring pyeloplasty when compared with the patients managed conservatively. The level of AKP significantly falls after pyeloplasty in the patients of HDN due to PUJO. There is a negative correlation with the preoperative level of enzyme NAG with split renal function in the patients of HDN requiring pyeloplasty.
Access this article online Website: www.jiaps.com DOI: 10.4103/0971-9261.91077 DOI Quick Response Code: Code
KEY WORDS: Alkaline phosphatase, gamma glutamyl transferase, N-acetyl-glucosaminidase, pelviureteric junction obstruction, urinary biomarkers, urinary enzymes
INTRODUCTION Pelviureteric junction obstruction (PUJO) is one of the most common causes of hydronephrosis (HDN) and renal insufficiency in children.[1-3] It is important to predict which cases of HDN will resolve spontaneously and which will require surgical treatment.[4-6] Investigations
like dynamic radioisotope scan, ultrasonography and, infrequently, intravenous pyelography are utilized for investigating these patients. [4] Certain urinary biomarkers have been used as indicators of renal damage in HDN patients.[7] Measurement of urinary enzymes can be used as biomarkers for various renal diseases.[8] We evaluated the role of lysosomal enzyme
Journal of Indian Association of Pediatric Surgeons / Jan-Mar 2012 / Vol 17 / Issue 1
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Rathod, et al.: Urinary enzymes in pelviureteric junction narrowing
N-acetyl--glucosaminidase (NAG) and brush border enzymes alkaline phosphatase (AKP) and gamma glutamyl transferase (GGT) in the diagnosis and followup of patients with HDN.
MATERIALS AND METHODS This is a prospective observational study from July 2009 to December 2010. All consecutive children with HDN due to suspected PUJO were included in the study. The patients managed by percutaneous nephrostomy, patients with urolithiasis and urine samples with positive bacterial cultures were excluded from the study. All the patients underwent blood urea and creatinine levels estimation, ultrasonography of abdomen, dynamic renal scan using ethylene dicysteine (EC) renography and urinary levels of NAG, AKP, GGT and creatinine (Cr). The levels of urinary enzymes were expressed as enzyme to Cr ratios as urinary NAG-to-Cr, urinary AKPto-Cr and urinary GGT-to-Cr ratios, expressed as mU/ mg, μmol/mg/min and IU/gm, respectively. Based on the EC scintigraphy, the patients were divided into two groups. Group A included patients with nonobstructed (t½ of less than 10 min) and equivocal (t½ of 10–20 min) renogram curve on the scan and the corresponding split renal function (SRF) of more than 40%. These patients were managed conservatively. Group B included patients with obstructed renogram curve on the scan, i.e. t½ of more than 20 min and corresponding SRF of less than 40%. These patients underwent pyeloplasty. N-Acetyl--D-glucosaminidase (NAG) was measured by a modification of the method of Maruhn.[9] Activity of AKP was assayed by the method of Bergmeyer using 4-nitro phenyl phosphate as a substrate.[10,11] Gama GGT was measured by a modification of the method of Szasz. [12] Statistical analysis was performed using statistical software SPSS V17.
RESULTS A total of 70 patients were included in the study, of which 29 patients were in group A and 41 patients were in group B. The mean age of group A patients was 20.6 months (range: 1–144 months) while in group B was 26.2 months (range: 2–120 months). There were seven females in group A while group B had three females. The gender difference was statistically comparable (P = 0.0803). Of the 29 patients in group A, 10 patients had left-sided HDN. Two patients in this group had bilateral renal involvement. On the other hand, in group B, 28 of 41 patients had left-sided PUJO. This difference in the side of renal involvement among the groups was significant (P = 0.0139). The mean ± standard deviation baseline SRF in group A was 50.6 ± 4.4, which remained unchanged at 3 and 8 months of follow-up (50.1 ± 2.1 and 50.6 ± 1.8, respectively). In group B, the mean preoperative SRF of 33.5 ± 14.5 significantly improved to 37.5 ± 12.7 at 3 months after surgery (P < 0.001). However, on further follow-up at 8 months, the mean SRF remained the same (37.8 ± 12.4, P = 0.6626). Table 1 demonstrates the drainage patterns of kidneys as reported by EC scan in group A patients. More than 50% of the patients showed improvement on the drainage within the observation period of 8 months from diagnosis, P < 0.001. Similarly, in group B, the renogram curves showed significant improvement in the drainage pattern after surgery. The simple linear regression of baseline enzyme levels of NAG, AKP and GGT with the SRF in group A showed that there was no correlation between the enzyme levels and SRF in this group. However, the linear regression graph of NAG levels with SRF in group B [Figure 1] showed a significant negative correlation (r2 = 0.198, P = 0.0035). The linear regression graph of AKP and GGT with SRF did not show any significant correlation in group B.
Table 1: Comparison of drainage patterns in both the groups as reported by EC scan Drainage Obstructed Equivocal Unobstructed No Comment Total
Group A (n)
Group B (n)
Baseline
3 months
8 months
Baseline
3 months
8 months
0 27 2 0 29
1 12 16 0 29
0 3 19 0 22
36 3 0 2 41
0 37 2 2 41
0 16 1 0 17
P-value
