Prognostic significance of captopril renography for managing congenital unilateral hydronephrosis

Early-in-Life Serum Aldosterone Levels Could Predict Surgery in Patients with Obstructive Congenital Anomalies of the Kidney and Urinary Tract: A Pilot Study

The aim of the study was to evaluate whether serum aldosterone levels or plasmatic renin activity (PRA) measured early in life (1-3 months) could predict a future surgical intervention for obstructive congenital anomalies of kidney and urinary tract (CAKUT). Twenty babies aged 1-3 months of life with suspected obstructive CAKUT were prospectively enrolled. The patients underwent a 2-year follow-up and were classified as patients needing or not needing surgery. In all of the enrolled patients, PRA and serum aldosterone levels were measured at 1-3 months of life and were evaluated as predictors of surgery by receiver-operating characteristic (ROC) curve analysis. Patients undergoing surgery during follow-up showed significantly higher levels of aldosterone at 1-3 months of life compared to those who did not require surgery (p = 0.006). The ROC curve analysis of the aldosterone for obstructive CAKUT needing surgery showed an area under the ROC curve of 0.88 (95%CI = 0.71-0.95; p = 0.001). The aldosterone cut-off of 100 ng/dL presented 100% sensitivity and 64.3% specificity and predicted surgery in 100% of cases. The PRA at 1-3 months of life was not a predictor of surgery. In conclusion, serum aldosterone levels at 1-3 months could predict the need for surgery during obstructive CAKUT follow-up.

Can urinary biomarkers detect obstruction defined by renal functional loss in antenatal hydronephrosis?

INTRODUCTION

Diagnosing obstruction and thus, assessment of need for surgery in the management of antenatal hydronephrosis may be challenging. Current diagnostic tests are not capable of indicating which patients are at risk for obstructive nephropathy. Biomarkers may play an important role in distinguishing these patients.

OBJECTIVE

The aim of this study is to evaluate if urinary biomarkers could differentiate obstruction (OBS) from non-obstructive dilation (NOD) in patients with antenatal hydronephrosis (AH) that underwent pyeloplasty due to loss of differential renal function (DRF).

STUDY DESIGN

Children with a history of AH and postnatal anteroposterior (AP) diameter ≥15 mm were included in this study of prospectively collected data between 2010 and 2018. The OBS group included patients who underwent pyeloplasty due to solely ≥10% subsequent decrease in DRF on a MAG-3 scan during follow-up. Patients with stable or improving hydronephrosis with no significant reduction in ipsilateral DRF (<10%) during follow-up formed the NOD group. Healthy children with no history of AH and a normal urinary ultrasound were taken as the control group. Urinary IP-10, MCP-1, KIM-1, NGAL, and Ca19-9 levels using ELISA were measured. In the OBS group, urine samples were obtained preoperatively and at 3rd post operative-month whereas in the NOD and control groups, samples were collected at the time of enrollment.

RESULTS

There were 24 children in the OBS and 27 children in the NOD groups. The control group consisted of 27 healthy children. The pre-operative bladder urine levels of biomarkers of the OBS group were significantly higher than in the NOD and control group (p < 0.05, for all). In terms of differentiating OBS from NOD, results of ROC analyses for the given cut-off values were as follows: 135.06 ng/mgCr (sensitivity 75%; specificity 66%, AUC = 0.735) for IP-10, 0.89 ng/mgCr (sensitivity 79.2%; specificity 88%, AUC = 0.802) for KIM-1, 367.65 pg/mgCr (sensitivity 62.5%; specificity 52%, AUC = 0.660) for MCP-1, 16.15 ng/mgCr (sensitivity 70.8%; specificity 70.4%, AUC = 0.669) for NGAL, and 55.5 U/mgCr (sensitivity 75%; specificity 66%, AUC = 0.676) for Ca 19-9. Moreover, when KIM-1 was combined with IP-10 and Ca19-9, sensitivity and specificity levels were 83% and 85% (AUC = 0.919), respectively.

CONCLUSION

In this novel study, which focused on scintigraphic DRF loss, KIM-1 was the most successful among all the biomarkers evaluated. Combination of IP-10, Ca19-9 and KIM-1 resulted increased diagnostic ability.

Interobserver agreement on cortical tracer transit in 99mTc-MAG3 renography applied to congenital hydronephrosis

OBJECTIVE

This study aims to evaluate interobserver agreement on visual analysis of technetium-99m mercaptoacetyltriglycine (Tc-MAG3) renal tissue transit used for the evaluation of antenatal hydronephrosis.

MATERIALS AND METHODS

Thirty-eight Tc-MAG3 diuretic renograms were retrospectively collected between 1 and 31 December 2015. The 1-min reframed images were presented to four nuclear medicine consultants and to two nuclear medicine residents, one in the first year of the training program and the others in their fourth and final year. These observers were asked to classify the radiotracer cortical transit (normal/delayed) based solely on visual assessment of the images. For the interobserver agreement, modified Fleiss' kappa (κ) analysis for multiple raters was carried out. For both groups, percentages of agreement were also calculated.

RESULTS

A total of 69 kidneys were evaluated. All four nuclear medicine consultants agreed on the classification of 88.4% of the kidneys. When the agreement of at least three of the four observers was considered, the percentage of agreement reached 98.6%. The two nuclear medicine residents agreed on the classification of 69.6% of the kidneys. The modified Fleiss' κ-value was 0.88 (95% confidence interval: 0.79-0.95) for the group of nuclear medicine consultants, indicating almost perfect agreement. For the residents, it was 0.39 (95% confidence interval: 0.16-0.59), suggesting fair agreement.

CONCLUSION

Our results seem to indicate that there is an almost perfect agreement in the qualitative identification of delayed cortical transit among physicians with experience at observing renographic images.

Urinary epidermal growth factor, monocyte chemotactic protein-1, and β2-microglobulin in children with ureteropelvic junction obstruction

BACKGROUND/PURPOSE

We demonstrated down-regulation of epidermal growth factor (EGF) and up-regulation of monocyte chemotactic protein-1 (MCP-1) in the renal parenchyma in children who underwent pyeloplasty for ureteropelvic junction obstruction (UPJO). These findings were paralleled by urinary levels of EGF and MCP-1 before and after surgery. The aim of this study is to evaluate the urinary excretion of these cytokines and β2-microglobulin (β2M) in children with urine flow impairment at the ureteropelvic junction or who underwent pyeloplasty.

METHODS

Seventy-six patients with UPJO and 30 normal children (CTRL) were enrolled in the study. The UPJO patients were divided into obstructive (12), functional (36), and operated (28). Epidermal growth factor, MCP-1, and β2M urinary levels were measured by enzyme-linked immunosorbent assay and normalized to urine creatinine.

RESULTS

Urinary β2M and MCP-1 increased significantly in the UPJO groups compared with the CTRL and significantly improved in the operated group. The obstructive group displayed reduced EGF excretion compared with the CTRL group. The urinary (u)EGF/uMCP-1, and uEGF/uβ2M ratios significantly decreased in both untreated groups. In the operated group, these ratios improved significantly.

CONCLUSIONS

The present study substantiates the role of urinary EGF, MCP-1, and β2M as markers of tubulointerstitial damage in human obstructive nephropathy. Furthermore, it suggests that surgical intervention is effective in the management of children with UPJO.

Captopril renography as a prognostic factor in obstructive hydronephrosis with preserved renal function

Hydronephrotic kidney with a differential renal function greater than 55% is defined as supranormal. The signification of this finding remains controversial. In this article, the authors reported a case of supranormal function in obstructive hydronephrosis. Differential renal functions were evaluated after administration of captopril and after pyeloplasty. The role of captopril renography as a prognostic factor for surgery is discussed.

Diuretic renography in hydronephrosis: renal tissue tracer transit predicts functional course and thereby need for surgery

PURPOSE

The recognition of those hydronephrotic kidneys which require therapy to preserve renal function remains difficult. We retrospectively compared the 'tissue tracer transit' (TTT) of (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG(3)) with 'response to furosemide stimulation' (RFS) and with 'single kidney function < 40%' (SKF < 40%) to predict functional course and thereby need for surgery.

METHODS

Fifty patients with suspected unilateral obstruction and normal contralateral kidney had 115 paired (baseline/follow-up) (99m)Tc-MAG(3) scintirenographies. Three predictions of the functional development were derived from each baseline examination: the first based on TTT (visually assessed), the second on RFS and the third on SKF < 40%. Each prediction also considered whether the patient had surgery. Possible predictions were 'better', 'worse' or 'stable' function. A comparison of SKF at baseline and follow-up verified the predictions.

RESULTS

The frequency of correct predictions for functional improvement following surgery was 8 of 10 kidneys with delayed TTT, 9 of 22 kidneys with obstructive RFS and 9 of 21 kidneys with SKF < 40%; for functional deterioration without surgery it was 2 of 3 kidneys with delayed TTT, 3 of 20 kidneys with obstructive RFS and 3 of 23 kidneys with SKF < 40%. Without surgery 67 of 70 kidneys with timely TTT maintained function. Without surgery 0 of 9 kidneys with timely TTT but obstructive RFS and only 1 of 16 kidneys with timely TTT but SKF < 40% lost function.

CONCLUSION

Delayed TTT appears to identify the need for therapy to preserve function of hydronephrotic kidneys, while timely TTT may exclude risk even in the presence of an obstructive RFS or SKF < 40%.

Diuretic renography in hydronephrosis: delayed tissue tracer transit accompanies both functional decline and tissue reorganization

The significance of delayed tissue tracer transit (TTT) of (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) has not been systematically evaluated in hydronephrosis. We sought to demonstrate that delayed TTT accompanies both functional decline and histomorphologic restructuring.

METHODS

Twenty 2- to 3-mo-old piglets with surgically induced partial unilateral ureteral stenosis were examined with magnetic resonance urography (MRU) to evaluate morphology and with (99m)Tc-MAG3 diuretic renography (DR) to determine single-kidney function (SKF), evaluate the response to furosemide stimulation (RFS), and assess TTT. All animals had DR and MRU before and after surgery and a third DR after surgery. Piglets were sacrificed after the final DR for renal histology. A total histologic score (THS) was generated.

RESULTS

Preoperative DR demonstrated nonobstructive RFS, timely TTT, and balanced SKF in all 20 kidneys. After ureteral ligature, MRU demonstrated pelvic dilatation in all piglets. The postoperative DRs revealed 12 kidneys with delayed TTT in one or both follow-ups. In these 12 kidneys, the SKF declined from 51% +/- 4% to 18% +/- 14%, and the THS was 9.0 +/- 4.0. Three kidneys always had timely TTT, balanced SKF, and a THS of 1.8 +/- 0.3. The contralateral, nonoperated kidneys had timely TTT and a THS of 1.2 +/- 0.9. Postoperative scintigrams showed that 3 of 8 kidneys (38%) with an obstructive RFS had timely TTT, which demonstrates that TTT and RFS are not equivalent.

CONCLUSION

In hydronephrosis, a delayed TTT of (99m)Tc-MAG3 accompanies both functional decline and histomorphologic restructuring in obstruction. According to the literature, a delayed TTT is determined by the filtration fraction of the kidneys and appears to identify an obstruction-mediated upregulated renin-angiotensin system.

Plasma renin activity for monitoring vesicoureteric reflux therapy: mid-term observations

OBJECTIVE

To study plasma renin activity (PRA) as an early marker for monitoring treatment of vesicoureteric reflux (VUR).

PATIENTS AND METHODS

Fifty-nine children (35 males and 24 females), mean age 43.3+/-26.5 (range 4.5-89) months, with various grades (I-V) of primary VUR were enrolled. PRA, renal scars, split renal function (SRF), glomerular filtration rate (GFR), serum creatinine, blood pressure and episodes of breakthrough urinary tract infection were monitored at regular intervals. Surgery was performed as per currently accepted criteria. PRA values were used for post-hoc analysis of results.

RESULTS

Thirty-eight children (64.4%) underwent anti-reflux surgery during the mean follow up of 17.1+/-3.1 months; 21 (35.6%) continued on non-operative follow up. Rise in PRA up to the time of surgery was seen in all patients. It normalized after surgery in 86%, and reduced but plateaued at a higher level than normal in 13.8% in the surgical group. While improvement in SRF and GFR was seen only in 2/38 (5.2%) and 12/38 (31.6%), respectively, blood pressure stabilized in 30.7% and serum creatinine showed inconsistencies. In non-operatively managed cases, improvement in SRF was seen in only one case and GFR in 14.2% of cases. However, 80.9% children showed a progressive rise in PRA throughout the period of non-operative follow up.

CONCLUSION

Current end points of non-operative management already cause irreversible renal damage by the time surgery is indicated. Our results suggest that serial measurement of plasma renin activity may help in better stratification of patients with moderate to high grade (III-V) VUR with respect to management and prognosis.

Chronic partial ureteral obstruction and the developing kidney

Although congenital urinary tract obstruction is a common disorder, its pathophysiology remains poorly understood and clinical practice is controversial. Animal models have been used to elucidate the mechanisms responsible for obstructive nephropathy, and the models reveal that renal growth and function are impaired in proportion to the severity and duration of obstruction. Ureteral obstruction in the neonatal rat or mouse leads to activation of the renin-angiotensin system, renal infiltration by macrophages, and tubular apoptosis. Nephrons are lost by glomerular sclerosis and the formation of atubular glomeruli, and progressive injury leads to tubular atrophy and interstitial fibrosis. Recovery following release of obstruction depends on the timing, severity, and duration of obstruction. Growth factors and cytokines are produced by the hydronephrotic kidney, including MCP-1 and TGF-beta1, which are excreted in urine and can serve as biomarkers of renal injury. Because MRI can be used to monitor renal morphology, blood flow, and filtration rate, its use might supplant current imaging modalities (ultrasonography and diuretic renography), which have significant drawbacks. Combined use of MRI and new urinary biomarkers should improve our understanding of human congenital obstructive nephropathy and should lead to new approaches to evaluation and management of this challenging group of patients.

Current diagnosis and management of fetal genitourinary abnormalities

Prenatal assessment with ultrasonography provides excellent imaging of fluid-filled structures (eg, hydronephrosis, renal cysts, and dilated bladder) and renal parenchyma. This information allows for the generation of a differential diagnosis, identification of associated anomalies, and assessment of the prenatal and postnatal risks of a given anomaly. This enhances parental education and prenatal and postnatal planning. This article discusses the current methods of diagnosis and management of fetal genitourinary anomalies, and also the postnatal evaluation and treatment of these conditions.

Posterior urethral valves: preliminary observations on the significance of plasma Renin activity as a prognostic marker

PURPOSE

A significant number of children with posterior urethral valves (PUVs) have chronic renal failure due to tubulointerstitial damage. Activation of the renin-angiotensin system is known to inflict this injury. We investigated the role of plasma renin activity (PRA) in patients with PUVs and sought to establish a relationship between renal damage and PRA.

MATERIALS AND METHODS

The records of patients with PUVs were reviewed regarding the time of valve ablation, serum creatinine, scars, grade of reflux and glomerular filtration rate (GFR). PRA was measured before and after valve ablation.

RESULTS

A total of 25 patients had PUVs (mean age 3.2 +/- 2.4 years, mean period of observation 4.5 +/- 1.2 years). Mean PRA was increased before valve ablation in all patients irrespective of age, and decreased after ablation. Of 25 patients 14 (56%) had renal damage, with a mean PRA of 36 +/- 4.5 ng/ml per hour compared to 26 +/- 8.2 ng/ml per hour in patients with normal renal function (chi-square 4.2 p = 0.01). Of the 14 patients with renal damage 9 (64%) had normal GFR at age 1 year but increased PRA. Of these 14 patients the accepted criteria for renal damage of increased serum creatinine, high grade reflux, scars and decreasing GFR were present in only 6 (43%), 3 (21%), 2 (14%) and 4 (29%), respectively. PRA was increased in all 14 cases.

CONCLUSIONS

PRA was increased before valve ablation and decreased after ablation. It is increased in patients with early renal damage. Our preliminary observations indicate that PRA may be helpful in identifying patients with early renal damage.

BIOMARKERS OF CONGENITAL OBSTRUCTIVE NEPHROPATHY: PAST, PRESENT AND FUTURE

PURPOSE

Congenital obstructive nephropathy constitutes one of the major causes of renal insufficiency in infants and children. This review addresses the need to define biomarkers that serve as surrogate end points for measuring the severity of obstruction, the evolution of renal maldevelopment and injury, and the response to medical or surgical intervention.

MATERIALS AND METHODS

The literature from the last 10 years was reviewed for biomarkers of congenital obstructive nephropathy. Sources of biomarkers included urine, blood, amniotic fluid, tissue and imaging techniques.

RESULTS

Previous markers of congenital obstructive nephropathy include sonographic renal pelvic diameter, quantitative diuretic renography, and markers of glomerular and tubular function. Attempts to correlate renal histological changes with differential renal function have been disappointing. Immunohistochemical analysis and laser capture microscopy should improve specificity. Most promising is the application of new insights into the cellular response of the developing kidney to urinary tract obstruction. These findings include components of the renin-angiotensin system, transforming growth factor-beta 1, monocyte chemoattractant protein-1 and epidermal growth factor. Microarray studies show unique patterns of gene expression by the neonatal rat kidney subjected to ureteral obstruction, and proteomics should provide even more sensitive biomarkers of obstructive nephropathy.

CONCLUSIONS

We must define the cellular and molecular bases of renal maldevelopment, focusing on the link between functional and developmental pathophysiology. These findings will lead to biomarkers that will optimize our management of congenital obstructive nephropathy.

Dorsal lumbotomy incision in paediatric pyeloplasty

BACKGROUND

The purpose of the present study was to comprehensively assess the results of surgical management of pelvi-ureteric junction (PUJ) obstruction using lumbotomy as the surgical approach.

METHODS

Records of 36 consecutive patients with unilateral PUJ obstruction who underwent pyeloplasty in the last 5 years were reviewed retrospectively. The investigations included renal function tests, ultrasound and serial renal diuretic scans. A micturating cystourethrogram was also done whenever indicated. A dismembered pyeloplasty via lumbotomy was the only surgical approach considered. Thirteen patients had a right pyeloplasty while 23 had a left pyeloplasty. Mean age at diagnosis was 57 months in 31 patients while five were antenatally diagnosed (range 1 month-12 years). Age at surgery ranged from 1 month to 12 years with a mean of 59.9 months. Nine children underwent surgery in infancy. Six patients had a preoperative percutaneous nephrostomy (PCN) placement, five for poorly functioning kidneys (less than 10% split renal function) and one for oliguria. Records were reviewed for age at diagnosis, age at surgery, duration of surgery, preoperative and postoperative split renal function.

RESULTS

The follow-up period in the present study ranged from 9 months to 68 months with a mean of 44.9 months. Mean duration of surgery was 78 min of the group as a whole but in PCN patients it was significantly more (100 min vs 71.3 min). Fourteen patients had an improvement in split renal function noticed at 3 and 6 months postoperatively, 17 patients had no change while one patient had a deterioration of split renal function. Four patients had a solitary functioning kidney and in all of these glomerular filtration rate improved postoperatively. Hospital stay was on the average 7.45 days with a range of 6-10 days. However, when a double-J (D-J) stent was used across the anastomosis and the uretero-vesical junction (transrenal D-J stenting), the mean stay was reduced to 3 days. All patients returned to full oral feeds by postoperative day 1. No incidences of wound related problems were encountered.

CONCLUSIONS

Pyeloplasty results in predictably good outcome in paediatric PUJ obstruction whenever indicated. The lumbotomy approach avoids muscle cutting, thereby minimizing complications related to wound and assisting with faster recovery. Keeping a double-J (D-J) stent across the anastomosis and the uretero-vesical junction (transrenal D-J stenting) reduces hospital stay.

Role of plasma renin activity in the management of primary vesicoureteric reflux: A preliminary report

BACKGROUND

Nonoperative management is the choice of therapy in most patients with primary vesicoureteric reflux (VUR). Such patients are regularly monitored for breakthrough urinary tract infection, deterioration of renal function, and progression/ appearance of new scars as the indicators for switching over to surgical intervention. In this descriptive study, we report our additional observations on serial measurement of plasma renin activity (PRA) in a group of such children followed prospectively.

METHODS

Twenty-six children (16 males and 10 females) with various grades (grades I to V) of primary VUR were enrolled. Besides the conventional investigations, we also monitored PRA. Ureteric reimplantation was performed based on established international criteria. PRA levels were correlated with the need for surgical intervention retrospectively.

RESULTS

Mean age at presentation was 39.3 months (range, 12 to 120 months). Nineteen children (73%) were subjected to ureteric reimplantation. The mean PRA in this group (N = 19) was 6.97 ng/mL/hour versus 3.28 ng/mL/hour in patients who were continued on nonoperative management (N = 7). Postoperatively, the PRA reduced and stabilized in all 18 patients at a mean value of 5.4 ng/mL/hour.

CONCLUSION

The currently accepted end points of medical management are inconsistent. On the other hand, 94.7% of children in the surgical group had shown an activation and a progressive increase in PRA. Postoperatively, the PRA was reduced and stabilized in all these patients. Our preliminary observations suggest that high PRA is a more sensitive indicator for surgical intervention as compared to the existing criteria.