Endovascular Treatment Failure of Renal Arteriovenous Malformation due to an Extrarenal Feeding Artery: A Case Report.

Renal arteriovenous malformation (RAVM) is a rare pathology. It may present with heamturia, hypertension, and congestive heart failure. Digital subtraction angiography (DSA) is the standard diagnostic choice, and endovascular embolization is a preferred procedure of management in most cases. The feeding branches of RAVM are reported to originate from renal arteries. In this report, a 43-year-old female with recurrent massive hematuria and left flank pain was described. Renal angiography revealed double renal arteries supplying the left kidney and multiple renal arteriovenous fistula formation around the renal pelvis. Embolization with coils and gelfoam was performed after which her hematuria subsided. One month later, the patient was readmitted to our hospital due to the relapse of massive hematuria following heavy physical activities. DSA found another feeding artery of the RAVM originating from the aorta around the 4th lumbar vertebra. After embolization of this arterial feeder, hematuria settled. There was no recurrence during a 10-month follow-up. To our knowledge, this is the first case of RAVM with an extrarenal feeding artery, and omission of this scenario can lead to treatment failure.

Double trouble - management of perinephric hematoma and renal vein thrombosis post percutaneous renal biopsy.

BACKGROUND: Performing percutaneous renal biopsy procedures in lupus nephritis (LN) and nephrotic syndrome presents a unique challenge to the nephrologist because of the risk of bleeding from the procedure and the hypercoagulable state in hypoalbuminemia. The management of a patient with venous thrombosis with perinephric hematoma post renal biopsy can be difficult if occurred. CASE PRESENTATION: We are presenting a case of perinephric hematoma following percutaneous renal biopsy in a 23-year-old man with lupus nephritis, nephrotic syndrome, and lower limbs deep vein thrombosis (DVT). The patient developed persistent frank haematuria, flank pain and acute urinary retention post-procedure. We have withheld his oral warfarin three days before the procedure, and no anticoagulation was given subsequently. Initial CT Angiography (CTA) renal showing stable hematoma and no visible evidence of vascular injury. Three weeks later, the patient still has persistent frank haematuria and a repeated CTA renal revealed new bilateral renal vein thrombosis. Considering the high risk of worsening symptomatic venous thrombosis, we gave subcutaneous enoxaparin sodium and restart oral warfarin despite ongoing haematuria. The frank haematuria resolved within two days of anticoagulation with no radiological evidence of worsening of the perinephric hematoma. The follow-up ultrasonography a month later showed resolution of the hematoma and renal vein thrombosis with no adverse effect. CONCLUSION: Our experience, in this case, highlighted the importance of case selection for percutaneous renal biopsy among high-risk patients. Additionally, a prolonged frank haematuria in post-renal biopsy with nephrotic syndrome warranted a reassessment, as a clinical presentation of post-procedure perinephric hematoma and renal vein thrombosis can overlap. We also demonstrated that restarting anticoagulation earlier than four weeks in a patient with renal vein thrombosis and post-renal biopsy perinephric hematoma can be safe in the selective case.

Rate of recurrent hydronephrosis after laparoscopic ureteroneocystostomy for ureteral endometriosis.

STUDY OBJECTIVE: To investigate the short-term outcomes of laparoscopic ureteroneocystostomy in patients with ureteral endometriosis (UE). DESIGN: Retrospective cohort study of consecutive patients who underwent surgery for the ureter endometriosis with hydronephrosis. SETTING: A private hospital that provide primary, secondary and tertiary care. PATIENTS: 30 consecutive patients with UE who underwent laparoscopic ureteroneocystostomy at our institution between May 2008 and April 2020. INTERVENTIONS: Laparoscopic ureteroneocystostomy, if necessary, hysterectomy, salpingo-oophorectomy, cystectomy, partial bladder resection, or partial bowel resection were performed. MEASUREMENTS AND MAIN RESULTS: The most common chief complaint was pelvic pain (40%). Endometriosis affected only the left ureter in 56.7% of patients, only the right ureter in 33.3%, and both ureters in 6.7%. Involvement of the ipsilateral ovary was confirmed in 64.3%. The most frequent location of UE was 1-3 cm above the UVJ (46.7%). A psoas hitch was performed in 7 patients (23.3%), and the Boari flap was used in 9 patients (30%). Hysterectomy was performed in 12 patients (40%), and 6 of them had a concomitant bilateral salpingo-oophorectomy (20%). In addition, 3 patients (10%) underwent partial bowel resection, and 2 patients (6.7%) underwent partial bladder resection. After surgery, 24 of 27 patients (80.0%) were free of sever hydronephrosis after surgery. Hydronephrosis recurred in a single patient (3.3%), but the grade of hydronephrosis improved significantly after surgery (P < 0.001). At 6 months of follow up, 4 patients (13.3%) experienced urinary tract infections and 2 patients (6.7%) reported dysuria. Patients reported a regression of dysmenorrhea symptoms (P < 0.001). CONCLUSION: This study shows that ureteroneocystostomy provides good results in terms of relapses and symptom control in patients with ureteral endometriosis.

Congenital midureteral stenosis in children: a 13-year retrospective study based on data from a large pediatric medical center.

BACKGROUND: Midureteral stenosis is very rare in children and can cause congenital hydronephrosis. We report our experience treating children with congenital midureteral stenosis at our center, focusing on the differences in preoperative diagnosis and treatment compared with other congenital obstructive uropathies. METHODS: We retrospectively reviewed the medical records of 26 children diagnosed with congenital midureteral stenosis at our center between January 2007 and December 2020, such as preoperative examination methods, intraoperative conditions, and postoperative follow-up results. RESULTS: Of the 1625 children treated surgically for ureteral narrowing, only 26 (1.6%) were diagnosed with midureteral stenosis, including 15 infants and 11 children. Eighteen (69.2%) were boys, 13 (50%) were affected on the left side, and 23 (88.5%) had isolated ureteral stenosis. Overall, 13 (50%) of the children presented with prenatal hydronephrosis, and 13 (50%) presented with abdominal pain or a mass. All the children had undergone urinary ultrasound and intravenous urography preoperatively; the diagnostic rate of ultrasound was 92.3%. Only 7 (26.9%) children had undergone pyelography. All the children had undergone surgery. The ureteral stenotic segment was less than 1 cm long in 25 (96.2)% of the children. The mean follow-up duration was 22 months (range: 6-50 months). One child developed anastomotic strictures. Urinary tract obstruction was relieved in the other children without long-term complications. CONCLUSIONS: Congenital midureteral stenosis is rare, accounting for 1.6% of all ureteral obstructions, and its diagnosis is crucial. Urinary ultrasound has a high diagnostic rate and should be the first choice for midureteral stenosis. Retrograde pyelography can be used when the diagnosis is difficult, but routine retrograde pyelography is not recommended. Congenital ureteral stenosis has a relatively short lesion range, largely within 1 cm. The treatment is mainly resection of the stenotic segment and end-to-end ureteral anastomosis, with a good prognosis.

A case of flank pain caused by ureteral intussusception accompanied with ureteral polyp.

BACKGROUND: Ureteral intussusception, a rarely reported unique condition, occurs primarily as a complication of ureteric tumours. CASE PRESENTATION: We present a case of ureteral intussusception accompanied with a large ureteral polyp periodically protruding into the bladder cavity occurring in a 56-year-old man who experienced vague flank pain and intermittent haematuria. The patient was successfully treated by ureteroscopic cauterization combined with partial ureterectomy with reanastomosis. CONCLUSIONS: This is the first report that describes polyp-related ureteral intussusception using comprehensive and representative ureteroscopic images and video. Our findings suggest that ureteroscopy is vital for diagnosis. Extensive biopsies through ureteroscopy are less invasive, and make it easier to exclude the presence of ureteral malignancies. Ureteroscopic resection of the whole polyp with its stalk and intussusceptum using Holmium: YAG laser did not seem viable in this case. However, cauterization of partial polyp tissues followed by open surgery for segmental resection of the ureter with reanastomosis is helpful in controlling such patient well-being.

Relevance of concurrent hypercalcemia in ureteric sarcoidosis complicated with bladder urothelial carcinoma: a case report.

BACKGROUND: Sarcoidosis is a multisystem inflammatory disorder and can affect any organ; however, ureteric involvement is extremely rare with only four cases reported in the literature to date, all of which were diagnosed with surgical ureteral resection including a nephroureterectomy. This study reports the first case of ureteric sarcoidosis controlled with medical therapy where a differential diagnosis was performed based on the diagnostic clue of hypercalcemia. A definitive diagnosis was established without surgical resection of the ureter. CASE PRESENTATION: A 60-year-old man presented with anorexia and weight loss. Blood tests showed renal dysfunction and hypercalcemia. Computed tomography revealed left hydronephrosis associated with left lower ureteral wall thickening, which showed high signal intensity on diffusion-weighted magnetic resonance imaging. Similarly, we detected a bladder tumor on cystoscopy, and a 2-cm-long stenosis was revealed by retrograde ureterography; therefore, ureteral cancer was suspected. Meanwhile, considering the clinical implication of hypercalcemia, a differential diagnosis of sarcoidosis was established based on elevated levels of sarcoidosis markers. Fluorodeoxyglucose positron emission tomography showed fluorodeoxyglucose accumulation in the left lower ureter, skin, and muscles, suggestive of ureteric sarcoidosis with systemic sarcoid nodules. For a definitive diagnosis, transurethral resection of the bladder tumor and ureteroscopic biopsy were performed. Histopathological examination revealed ureteric sarcoidosis with bladder urothelial carcinoma. Following an oral administration of prednisolone, hypercalcemia instantly resolved, the renal function immediately improved, and the left ureteral lesion showed complete resolution with no recurrence. CONCLUSIONS: In this case, the co-occurrence of ureteral lesion with bladder tumor evoked a diagnosis of ureteral cancer. However, considering a case of ureteral lesion complicated with hypercalcemia, assessment for differential diagnosis was performed based on the calcium metabolism and sarcoidosis markers. In cases of suspected ureteric sarcoidosis from the assessment, pathological evaluation with ureteroscopic biopsy should be performed to avoid nephroureterectomy.

Ureteral endometriosis in patients with deep infiltrating endometriosis: characteristics and management from a single-center retrospective study.

PURPOSE: As a serious type of deep infiltrating endometriosis (DIE), ureteral endometriosis (UE) can result in decreased kidney function. The aims of this study are to investigate risk factors and surgical treatments for UE. METHODS: The study enrolled 329 patients with deep infiltrating endometriosis, who were treated with laparoscopic surgery between January 2014 to September 2018. All patients were divided into one of two groups: UE or non-UE. Clinical information and other surgery variables of the two groups were examined. RESULT: Out of 329 patients with DIE, 68 (20.67%) cases of UE were diagnosed. Among them, 37 patients also had hydroureteronephrosis. In a multivariate analysis, the variables revised American Fertility Society (rAFS) stage IV, uterosacral ligament (USL) DIE lesion ≥ 3 cm in diameter and previous surgery for endometriosis significantly increased the risk of UE. A total of 27.03% (10/37) of patients with UE and hydroureteronephrosis showed decreased kidney function. Ureterolysis was performed in 59 patients, and an ureteroneocystostomy was performed in 9 patients. A double-J stent was placed in 37 patients with UE. Only 1 patient developed acute pyelonephritis postoperatively. During more than 2 years of follow-up, no patient experienced recurrence. CONCLUSIONS: The variables of rAFS stage IV, USL DIE lesion ≥ 3 cm in diameter and previous surgery for endometriosis significantly increased the risk of UE. Laparoscopic ureterolysis and ureteroneocystostomy are feasible and safe procedures with low complication and recurrence rates.

Kidney Blow Out Due to Inguinal Herniation of the Ureter in an Infant.

Ureteroinguinal herniation is a rare event, usually diagnosed during the surgical repair of inguinal hernias. Here, we describe the first case of a kidney blow out due to this condition in a male infant.

Should contrast CT urography replace non-contrast CT as an investigation for ureteric colic in the emergency department in those aged 65 and over?

PURPOSE: Elderly patients with upper tract urothelial cancer (UTUC) may present with colic and microscopic haematuria, mimicking urolithiasis. Patients presenting to emergency departments with acute ureteric colic are investigated with a CT KUB. CT urography (CTU) identifies UTUC better than a CT KUB. Thus, there is a possibility that a CT KUB may miss UTUC. METHODS: We studied patients aged 65 years or over presenting to the emergency department with ureteric colic and microscopic haematuria who had a CT KUB between January 2014 and October 2016. Patients who had both CT KUB and CTU were then compared to determine if CT KUB had missed a UTUC and if the diagnoses were concordant by the two tests. A radiologist independent from the reporting radiologists reviewed images as well as their reports. According to the Health Research Authority, England regulations, we did not obtain an ethical review on a voluntary basis for this retrospective study. RESULTS: Four hundred eighty-five patients [228 (47.01%) male and 257 (52.99%) female] had a CT KUB scan over the 34-month period. Their mean age was 74 (SD 6.97) [males 73 (SD 6.42), females 75 (SD 7.42)] years. One hundred eighty-seven scans were normal. Ureteric calculi (167), renal calculi (58) and renal cysts (28) were most frequent diagnoses. The diagnosis was uncertain in 33 patients (6.8%) [16 (48.49%) males and 17 (51.51%) females]. The mean age of this group of patients was 74 (SD 6.64) [males 73 (SD4.43), females 74 (SD7.64)] years. These patients had a CTU for clarity. CTU identified one UTUC not identified by CT KUB (0.2%), corroborated the diagnosis of a ureteric tumour in one patient and excluded UTUC in two others. CTU diagnosed two new bladder tumours and an endometrial tumour. Diagnoses were concordant between CT KUB and CTU in 17 of 33 patients (51.5%). CONCLUSIONS: CT KUB scans for patients 65 years and over presenting with ureteric colic is justified. Only a small proportion of patients will subsequently require the higher radiation dose CTU as the probability of missing UTUC is low.

Amyloidosis and acute hemorrhage of the kidney, ureter, and bladder.

Gross hematuria is a common occurrence in adults. The differential diagnosis is extensive, including: malignancy, trauma, inflammation of the urinary tract, and stones. While, urinary tract amyloidosis represents only a small percentage of causative gross hematuria, it is concerning because of its superficial resemblance to malignant processes. We report the case of an 82-year-old male with concurrent primary amyloidosis of the kidney, ureter and bladder in the setting of acute hemorrhage. Histopathological examination of several biopsied samples confirmed our diagnosis. A nephroureterectomy with bladder cuff was successfully performed without complication along with watchful waiting for the bladder amyloidosis.

Pharmacologic interventions to treat renal colic pain in acute stone episodes: Systematic review and meta-analysis.

OBJECTIVE: To assess effectiveness of pharmacologic interventions to relieve pain in patients suffering an acute stone episode. METHODS: Relevant trials that included patients with acute renal colic and radiological findings of urinary stones were identified in four databases. The main outcome was pain relief evaluated by Visual Analogue Scale score (VAS). RESULTS: In overall, diclofenac was superior to other NSAIDs for pain relief (MD of -12.57 [95% CI: -19.26, -5.88]). Paracetamol was superior to morphine for pain reduction at 30minutes (MD of -3.92 [95% CI: -6.41, -1.43]) and also to placebo at 15minutes (MD of -24.77 [95% CI: -33.19, -16.35]) and at 30minutes (MD of -16 [95% CI:-29, -2.96]) after drug administration. Finally, diclofenac was superior to paracetamol for pain reduction at 60 (MD of 6.60 [95% CI: 4.37, 8.83]) and 90minutes (MD of 3.4 [95% CI: 2.01, 4.79]). CONCLUSIONS: Diclofenac was superior to other NSAIDs and paracetamol for diminishing pain in patients suffering an acute stone episode. Paracetamol was superior to morphine and placebo for short pain relief. Future trials should address the role of paracetamol in the management of pain in patients suffering an acute stone episode.

[Technical features of intestinal ureteroplasty. art 6: simultaneous ureteral and bladder substitution].

AIM: To present the results and technical features of different methods of simultaneous ileal ureteral and bladder substitution. MATERIALS AND METHODS: From 2001 to 2016, 154 patients (mean age 52+/-9.2 years) underwent ileal and appendicular ureteroplasty. Of them, 70 (45.4%) were men and 84 (54.6%) women. Among them, 49 (31.8%) patients underwent ureteroplasty concurrently with orthotopic ileocystoplasty. The Studers ileal-ureter cystoplasty and Y-shaped bladder and ureteral reconstruction were performed in 38 (77.5%) and 11 (24.5%) cases, respectively. RESULTS: Early postoperative complications occurred in 8 (16.3%) patients: 4 of them suffered recurrent bouts of pyelonephritis, 3 experienced an acute adhesive intestinal obstruction, and another one had a failure the right-sided pouch-ureteral anastomosis. Late postoperative complications occurred in 7 (14.3%) patients. Of them, 3 suffered recurrent bouts of chronic pyelonephritis, 2 developed a pouch-ureteral-pelvic reflux, and 2 had strictures of ileoureteral anastomosis, requiring antegrade dilation with ureteral stenting. CONCLUSION: Simultaneous ureteral and bladder substitution is one of the most challenging and traumatic surgical interventions. Sometimes, due to severe comorbidities, disorders of upper tract urodynamics and decreased renal function, two-stage surgery may be necessary. At the first stage, cystectomy with cutaneous ureterostomy should be performed, and then, after the patients stabilization ileal substitution of the bladder and pelvic parts of ureters may be done.

The Fate of Primary Nonrefluxing Megaureter: A Prospective Outcome Analysis of the Rate of Urinary Tract Infections, Surgical Indications and Time to Resolution.

PURPOSE: We examined data on a cohort of patients with primary nonrefluxing megaureter to determine risk factors for febrile urinary tract infection, indications for surgery and time to resolution. MATERIALS AND METHODS: The records of patients younger than 24 months with primary nonrefluxing megaureter were prospectively captured from 2008 to 2015. Six a priori defined variables were studied, including gender, circumcision status, hydronephrosis SFU (Society for Fetal Urology) grade (low--1 and 2 vs high--3 and 4), continuous antibiotic prophylaxis use, ureteral dilatation (greater than 11 mm) and tortuosity. Univariate analyses and Cox hazard regression were done for febrile urinary tract infection risk factors. Resolution trends were analyzed using Kaplan-Meier curves. RESULTS: Mean ± SD age at the first clinic visit was 3.7 ± 4 months and mean followup was 26.3 ± 16.6 months. Of 80 patients with primary megaureter 66 (83%) had high grade hydronephrosis, 72 (90%) were male, 21 (26%) were circumcised and 40 (50%) had ureteral dilatation greater than 11 mm at baseline. Overall continuous antibiotic prophylaxis was prescribed to 34 patients (43%) and febrile urinary tract developed infection in 27 (34%) at a mean age of 5.8 months (median 3, range 1 to 24). Cox regression identified uncircumcised male gender (HR 3.4, 95% CI 1.1-10.7, p = 0.04) and lack of continuous antibiotic prophylaxis (HR 4.1, 95% CI 1.3-12.7, p = 0.01) as independent risk factors for febrile urinary tract infection. The 19 surgical patients (24%) had a larger mean ureteral diameter immediately preoperatively than those who did not require surgery (17 ± 5 vs 12 ± 4 mm, p <0.01). Kaplan-Meier curves showed that 85% of primary nonrefluxing megaureters that did not require surgery resolved in a median of 17 months. CONCLUSIONS: Febrile urinary tract infection developed in 34% of patients with primary nonrefluxing megaureter within the first 6 months of life. Circumcision and continuous antibiotic prophylaxis significantly decreased febrile urinary tract infection rates in those infants. Ureteral diameter 17 mm or greater was significantly associated with a higher rate of surgical intervention. Overall 76% of megaureters resolved during a median followup of 19 months.

Partial Nephrectomy in the Overweight Patient: an Overview.

The diagnosis and treatment of kidney cancer continues to evolve with advances in imaging and surgical approaches. The use of nephron sparing surgery (NSS) has become the operation of choice for treating small renal masses. Yet, technical difficulty and a variety of approaches have left debate for best method in the overweight population. This review summarizes the current knowledge in the open, laparoscopic, and robotic approaches to identify key risk factors, general assessments, complication rates, and the influence of body habitus for each approach.

Iliac Artery-Uretero-Colonic Fistula Presenting as Severe Gastrointestinal Hemorrhage and Hematuria: A Case Report and Review of the Literature.

Arterioenteric fistulas represent an infrequent but potentially fatal cause of gastrointestinal hemorrhage. Patients often present in extremis from shock and sepsis. This mandates a rapid diagnosis so that prompt, potentially life-saving interventions can be performed. We report the case of a 35-year-old man who presented with hematuria and hematochezia secondary to an iliac artery-uretero-colonic fistula that developed years after open common iliac artery aneurysm repair. His condition rapidly progressed to hemorrhagic shock, and he underwent successful endovascular treatment with a covered stent graft as a bridge to definitive open surgery. Subsequently, graft explantation, extra-anatomic arterial bypass, bowel resection, and ureter ligation was undertaken. A summary of the literature on iliac artery-enteric fistulas follows.

Implications of paraureteral diverticulum for the management of vesicoureteral reflux.

OBJECTIVES: To investigate the clinical importance of paraureteral diverticulum in the management of vesicoureteral reflux by analyzing the relationship between paraureteral diverticulum and recurrent urinary tract infections. METHODS: We retrospectively reviewed 131 children diagnosed with vesicoureteral reflux. We diagnosed vesicoureteral reflux and paraureteral diverticulum by initial voiding cystourethrography and defined "delayed ureteral drainage" as the presence of contrast media in the upper urinary tract on delayed films after voiding. We analyzed the relationships between paraureteral diverticulum, delayed ureteral drainage and recurrent urinary tract infections. RESULTS: The mean age at diagnosis of vesicoureteral reflux was 20.7 months. Of the 202 refluxing ureters, 55 (27.2%) had a paraureteral diverticulum. Of the 55 ureters with paraureteral diverticulum, 51 (92.7%) showed delayed ureteral drainage of refluxing contrast, which was significantly higher than the percentage of delayed ureteral drainage in ureters without paraureteral diverticulum (P < 0.001). On multivariate analysis of the effect of reflux grade or paraureteral diverticulum on delayed ureteral drainage of refluxing contrast, the odds ratio of paraureteral diverticulum was 11.47 (P < 0.001). In addition, the risk of recurrent urinary tract infections increased in ureters with paraureteral diverticulum (P = 0.020). CONCLUSIONS: In patients with vesicoureteral reflux and paraureteral diverticulum, the risk of recurrent febrile urinary tract infections seems to increase. Therefore, more progressive surveillance and treatment protocols should be considered in these patients.

[A young woman with hydronephrosis and ureteritis cystica]. / Een jonge vrouw met hydronefrose.

A 38-year-old woman with urosepsis and persistent unilateral hydronephrosis after antibiotic treatment. Antegrade pyelogram shows urine flow obstruction to the bladder. The whole ureter shows multiple small smooth-walled round lucent filling defects projecting into the lumen. The diagnosis ureteritis cystica was made.

Intrinsic ureteric obstruction secondary to endometriosis: a rare clinical entity causing obstructive uropathy and renal failure.

Ureteral endometriosis is rare and can be a silent clinical entity, which can potentially lead to serious complications such as obstructive uropathy, sepsis and renal failure. A high clinical suspicion is required especially in childbearing age groups due to non-specific presentation such as renal colic, recurrent urinary tract infection (UTI), renal failure or asymptomatic hydronephrosis.A woman in her 40s presented with febrile UTI and flank pain. She reportedly suffered from recurrent UTIs in the past. Initial workup revealed an infected, obstructed left renal collecting system with gross hydronephrosis and hydroureter to the distal ureter on a significant gynaecological background of severe endometriosis requiring hysterectomy in the past.CT showed chronic obstructive changes and soft tissue nodules within the renal pelvis with no radio-opaque stones. She underwent emergent ureteric stent insertion. Functional imaging demonstrated only 1% contribution of the left kidney with a preserved estimated glomerular filtration rate of 65 mL/min/1.73 m2Endoscopic evaluation of ureters found extensive soft tissue lesions throughout the dilated left collecting system with biopsy-confirmed endometriosis. Subsequently, she underwent laparoscopic nephroureterectomy due to extensive ureteric involvement and chronically obstructed non-functioning kidney. Histopathology demonstrated completely obstructing ureteral endometriosis.Ureteric obstruction secondary to endometriosis can be due to extrinsic or intrinsic disease. In addition to initial assessment with CT urogram MRI may be helpful to evaluate soft tissue thickening. Endoscopic assessment with ureteroscopy and biopsy is required for tissue diagnosis. Surgery is often the treatment of choice, ranging from ureteroureterostomy, ureteroneocystostomy or nephroureterectomy in severe cases.Ureteral endometriosis is a rare clinical entity, clinicians should remain vigilant about common presentations of this rare entity, early diagnosis and prompt treatment is crucial to prevent progression to renal failure.