Use of Intravenous Gadolinium-based Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Inaugural consensus statements were developed and endorsed by the American College of Radiology (ACR) and the National Kidney Foundation to improve and standardize the care of patients with kidney disease who have indication(s) to receive ACR-designated group II or group III intravenous gadolinium-based contrast media (GBCM). The risk of nephrogenic systemic fibrosis (NSF) from group II GBCM in patients with advanced kidney disease is thought to be very low (zero events following 4931 administrations to patients with estimated glomerular filtration rate [eGFR] <30 mL/min per 1.73 m2; upper bounds of the 95% confidence intervals: 0.07% overall, 0.2% for stage 5D chronic kidney disease [CKD], 0.5% for stage 5 CKD and no dialysis). No unconfounded cases of NSF have been reported for the only available group III GBCM (gadoxetate disodium). Depending on the clinical indication, the potential harms of delaying or withholding group II or group III GBCM for an MRI in a patient with acute kidney injury or eGFR less than 30 mL/min per 1.73 m2 should be balanced against and may outweigh the risk of NSF. Dialysis initiation or alteration is likely unnecessary based on group II or group III GBCM administration. This article is a simultaneous joint publication in Radiology and Kidney Medicine. The articles are identical except for stylistic changes in keeping with each journal's style. Either version may be used in citing this article.

Use of Intravenous Iodinated Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Intravenous iodinated contrast media are commonly used with CT to evaluate disease and to determine treatment response. The risk of acute kidney injury (AKI) developing in patients with reduced kidney function following exposure to intravenous iodinated contrast media has been overstated. This is due primarily to historic lack of control groups sufficient to separate contrast-induced AKI (CI-AKI; ie, AKI caused by contrast media administration) from contrast-associated AKI (CA-AKI; ie, AKI coincident to contrast media administration). Although the true risk of CI-AKI remains uncertain for patients with severe kidney disease, prophylaxis with intravenous normal saline is indicated for patients who have AKI or an estimated glomerular filtration rate less than 30 mL/min/1.73 m2 who are not undergoing maintenance dialysis. In individual high-risk circumstances, prophylaxis may be considered in patients with an estimated glomerular filtration rate of 30-44 mL/min/1.73 m2 at the discretion of the ordering clinician. This article is a simultaneous joint publication in Radiology and Kidney Medicine. The articles are identical except for stylistic changes in keeping with each journal's style. Either version may be used in citing this article.

Percutaneous Renal Biopsy Using an 18-Gauge Automated Needle Is Not Optimal.

BACKGROUND: As percutaneous renal biopsies (PRBs) are increasingly performed by radiologists, an increase in the use of 18-gauge automated needle stands to compromise adequacy. We compare the adequacy and safety of PRB with 14-, 16-, and 18-gauge automated needles. METHODS: PRB of native (N-592) and transplant (T-1,023) kidneys was performed from January 2002 to December 2019 using real-time ultrasound. Baseline clinical and laboratory data, biopsy data (number of cores, total glomeruli, and total glomeruli per core), and outcome (hematoma on renal US at 1-h, complications, and transfusion) were collected prospectively. PRB with N14g (337) versus N16g (255) and T16g (892) versus T18g (131) needles were compared. A p value of <0.05 was significant. RESULTS: PRB with an 18-g needle yielded the lowest number of total glomeruli per biopsy (N14g vs. N16g: 33 ± 13 vs. 29 ± 12, p < 0.01 and T16g vs. T18g: 34 ± 16 vs. 21 ± 11, p < 0.0001), significantly fewer total glomeruli per core (T16g vs. T18g: 12.7 ± 6.4 vs. 9.6 ± 5.0, p < 0.001 and N16g vs. T18g: 14.2 ± 6.3 vs. 9.6 ± 5.0, p < 0.001). A hematoma by renal US 1-h post-PRB was similar for native (14g-35% vs. 16g-29%, p = 0.2), and transplant biopsies (16g-10% vs. 18g-9%, p = 0.9) and the complication rate for native (14g-8.9% vs. 16g-7.1%, p = 0.5), transplant biopsies (16g-4.6% vs. 18g-1.5%, p = 0.2) and transfusion rate for native (14g-7.7% vs. 16g-5.8%, p = 0.4), and transplant biopsies (16g-3.8% vs. 18g-0.8%, p = 0.1) were similar irrespective of needle size. CONCLUSIONS: PRB of native and transplant kidneys with the use of a 16-gauge needle provides an optimal sample. However, our experience in transplant biopsies suggests the use of an 18-gauge needle stands to jeopardize the diagnostic accuracy of the PRB while not improving safety.

Changing Trends in the Performance of Percutaneous Renal Biopsy from Nephrologist to Interventional Radiologist: A Single-Center Experience.

BACKGROUND: Percutaneous renal biopsy of native kidneys (PRB) has been an integral part of the practice of nephrology. However, over the past 30 years, PRB has transitioned from a procedure performed only by nephrologists to interventional radiologists (IRs). We surveyed practicing nephrologists completing training in our program to determine the clinical practice patterns of PRB. METHODS: The 78 fellows completing the nephrology program at Rush University Medical Center from June 1984 through June 2017 were successfully contacted and surveyed regarding their opinion on adequacy of their training and whether they performed PRB in practice and if not or no longer, why. To evaluate for differences in the performance of PRB over time, a comparison of 4 periods of fellowship completion (i.e., 1984-1990, 1991-2000, 2001-2010, 2011-2017) was performed. RESULTS: All 78 nephrologists felt they had been adequately trained to perform PRB. PRB was performed by 45 (58%) nephrologists post-fellowship, but a significant decline was observed over the 4 periods of time from 1984 to 2017 (100 vs. 86 vs. 52 vs. 20%, p < 0.0001). The primary reason that 33 nephrologists did not perform PRB was that it was too time consuming and IR was available to perform PRB. Of the 71 nephrologists still in practice only 12 (17%) continue to perform PRB. A greater proportion of nephrologists completing training from 1984-1990 continue to perform PRB relative to those trained after 1990. The universal reason that nephrologists were no longer performing PRB was again an issue of time and the fact that IRs were available to perform PRB. CONCLUSION: We find that there has been a significant transition over time in the performance of PRB by a nephrologist to IR. The major reason for this is the time burden associated with PRB and the availability of IRs.

Pathophysiology of Hepatorenal Syndrome.

Hepatorenal syndrome type 1 (HRS-1) is a unique form of acute kidney injury that affects individuals with decompensated cirrhosis with ascites. The primary mechanism leading to reduction of kidney function in HRS-1 is hemodynamic in nature. Cumulative evidence points to a cascade of events that led to a profound reduction in kidney perfusion. A state of increased intrahepatic vascular resistance characteristic of advanced cirrhosis and portal hypertension is accompanied by maladaptive peripheral arterial vasodilation and reduction in systemic vascular resistance and mean arterial pressure. As a result of a fall in effective arterial blood volume, there is a compensatory activation of the sympathetic nervous system and the renin-angiotensin system, local renal vasoconstriction, loss of renal autoregulation, decrease in renal blood flow, and ultimately a fall in glomerular filtration rate. Systemic release of nitric oxide stimulated by the fibrotic liver, bacterial translocation, and inflammation constitute key components of the pathogenesis. While angiotensin II and noradrenaline remain the critical mediators of renal arterial and arteriolar vasoconstriction, other novel molecules have been recently implicated. Although the above-described mechanistic pathway remains the backbone of the pathogenesis of HRS-1, other noxious elements may be present in advanced cirrhosis and likely contribute to the renal impairment. Direct liver-kidney crosstalk via the hepatorenal sympathetic reflex can further reduce renal blood flow independently of the systemic derangements. Tense ascites may lead to intraabdominal hypertension and abdominal compartment syndrome. Cardio-hemodynamic processes have also been increasingly recognized. Porto-pulmonary hypertension, cirrhotic cardiomyopathy, and abdominal compartment syndrome may lead to renal congestion and complicate the course of HRS-1. In addition, a degree of ischemic or toxic (cholemic) tubular injury may overlap with the underlying circulatory dysfunction and further exacerbate the course of acute kidney injury. Improving our understanding of the pathogenesis of HRS-1 may lead to improvements in therapeutic options for this seriously ill population.

Accuracy of a GFR estimating equation over time in people with a wide range of kidney function.

BACKGROUND: Change in glomerular filtration rate (GFR) is important for clinical decision making. GFR estimates from serum creatinine level provide an unbiased but imprecise estimate of GFR at single time points. However, the accuracy of estimated GFR over time is not well known. STUDY DESIGN: Longitudinal study of diagnostic test accuracy. SETTINGS & PARTICIPANTS: 4 clinical trials with longitudinal measurements of GFR and serum creatinine on the same day, including individuals with and without kidney disease with a wide range of kidney function, diverse racial backgrounds, and varied clinical characteristics. INDEX TEST: GFR estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. REFERENCE TEST: GFR measured using urinary clearance of (125)I-iothalamate. RESULTS: Data included 19,735 GFR measurements in 3,531 participants during a mean follow-up of 2.6 years. Mean values at baseline for measured and estimated GFR and error (measured GFR - estimated GFR) were 73.1 (95% CI, 71.6 to 74.5), 72.7 (95% CI, 71.5 to 74.0), and 0.14 (95% CI, -0.35 to 0.63) mL/min/1.73 m(2), respectively. Mean rates of change in measured and estimated GFR and error were -2.3 (95% CI, -2.4 to -2.1), -2.2 (95% CI, -2.4 to -2.1), and -0.09 (95% CI, -0.24 to 0.05) mL/min/1.73 m(2) per year (P < 0.001, P < 0.001, and P = 0.2, respectively). Variability (ie, standard deviation) among participants in rate of change in measured GFR, estimated GFR, and error was 4.3, 3.4, and 3.3 mL/min/1.73 m(2) per year, respectively. Only 15% of participants had a rate of change in error >3 mL/min/1.73 m(2) per year, and only 2% had a rate of change in error >5% per year. LIMITATIONS: Participants' characteristics were not available over time. CONCLUSION: The accuracy of GFR estimates did not change over time. Clinicians should interpret changes in estimated GFR over time as reflecting changes in measured GFR rather than changes in errors in the GFR estimates in most individuals.

The Challenges of Diagnosing Nondilated Obstructive Uropathy: A Case Report.

Rationale: Nondilated obstructive uropathy (NDOU) is a rare cause of acute renal failure reported in less than 5% of cases of obstructive uropathy. It is typically associated with intrapelvic malignancies and diseases causing retroperitoneal lymphadenopathy and retroperitoneal fibrosis. As these conditions may prevent radiographic dilation of the collecting system, the diagnosis of NDOU may be missed by usual diagnostic testing. Presenting concerns of the patient: We present a case of acute anuric renal failure in a middle-aged woman with metastatic breast cancer associated with abdominal and retroperitoneal lymphadenopathy. Acute kidney injury was initially deemed secondary to drug-induced acute tubular necrosis (ATN) from bisphosphonate; however, there remained a high clinical suspicion of NDOU due to the presence of enlarged retroperitoneal lymph nodes on CT abdomen and pelvis with concerns for encasement of bilateral renal pelvic regions and ureters. Diagnoses: The patient underwent a retrograde pyelogram which demonstrated questionable narrowing bilaterally at the level of the renal pelvices. This led to an even stronger clinical suspicion of NDOU and urology service was consulted for evaluation. Intervention: Bilateral ureteral stents were placed by urology which led to robust urine output and rapid reversal of renal failure over the next 24 to 48 hours. Outcomes: Despite 2 weeks of anuria and hemodialysis, this patient's creatinine came back to her baseline. She was able to discontinue hemodialysis and her creatinine stabilized at 88.4 µmol/L (1 mg/dL). Teaching points: Nondilated obstructive uropathy is rare but important diagnosis that requires a high clinical suspicion in the appropriate clinical scenario. The lack of dilatation is believed to be related to encasement of the collecting system by tumor, fibrosis, or as in our case metastatic retroperitoneal lymphadenopathy. As this diagnosis cannot be overlooked, aggressive direct visualization or even intervention with internal or external stenting may be required to both diagnose and treat this condition.

Justification: L'uropathie obstructive sans dilatation (UOSD) est une cause rare d'insuffisance rénale aiguë (IRA) rapportée dans moins de 5 % des cas d'uropathie obstructive. Elle est généralement associée à des tumeurs malignes intrapelviennes et de maladies entraînant une lymphadénopathie rétropéritonéale et une fibrose rétropéritonéale. Ces conditions pouvant empêcher la dilatation radiographique du système collecteur, il arrive que le diagnostic de l'UOSD soit manqué lors des tests de diagnostic habituels. Présentation du cas: Nous présentons un cas d'IRA anurique chez une femme d'âge moyen atteinte d'un cancer du sein métastatique associé à une lymphadénopathie abdominale et rétropéritonéale (LAR). L'IRA avait initialement été considérée comme secondaire à une nécrose tubulaire aiguë induite par le bisphosphonate. La présence de ganglions lymphatiques rétropéritonéaux hypertrophiés sur la tomographie de l'abdomen et du bassin a toutefois soulevé un doute clinique d'UOSD; une obstruction des régions bilatérales du bassinet rénal et des uretères a été soupçonné. Diagnostic: La patiente a subi un pyélogramme rétrograde qui a montré un rétrécissement bilatéral suspect au niveau des bassinets rénaux, ce qui a soulevé un doute clinique encore plus important quant à la présence d'une UOSD. Le service d'urologie a été consulté pour évaluation. Intervention: Des endoprothèses urétérales ont été insérées bilatéralement par urologie. L'intervention a entraîné une forte production d'urine et la disparition de l'insuffisance rénale dans les 24 à 48 heures suivantes. Résultats: Malgré deux semaines d'anurie et d'hémodialyse, le taux de créatinine de la patiente est retourné à sa valeur initiale. La patiente a pu interrompre l'hémodialyse et son taux de créatinine s'est stabilisé à 88,4 micromoles/L (1 mg/dl). Enseignements tirés: Le diagnostic de l'UOSD est rare, mais important, car il requiert un doute clinique élevé dans le scénario clinique approprié. On pense que l'absence de dilatation pourrait être liée à l'obstruction du système collecteur rénal par une tumeur ou en raison d'une fibrose ou, comme ici, d'une lymphadénopathie rétropéritonéale métastatique. Puisque le diagnostic de l'UOSD ne doit pas être négligé, une visualisation directe plus poussée et l'insertion d'une endoprothèse interne ou externe pourraient s'avérer nécessaires pour diagnostiquer et traiter cette affection.

Successful treatment of refractory hypertension with bilateral nephrectomy in a patient with chronic kidney disease stage 3.

We present a case of life-threatening refractory hypertension (rHTN) in a patient with stage 3b chronic kidney disease that was unresponsive to open surgical renal denervation (RDN) but responded to bilateral nephrectomy (BLN). Both RDN and BLN reduce the increased sympathetic activation in rHTN. However, RDN has yet to show reductions in blood pressure adequate for the average patient with rHTN, and BLN has thus far been reserved for patients with preexisting end-stage kidney disease (ESKD). Our case suggests that there are patients with rHTN that warrant consideration of BLN prior to developing ESKD.

Unexpectedly severe metabolic acidosis associated with sodium thiosulfate therapy in a patient with calcific uremic arteriolopathy.

Calcific uremic arteriolopathy, formerly known as calciphylaxis is a devastating condition that primarily affects patients with end-stage renal disease. The lesions can progress to massive ulcerations of the subcutaneous tissue that are associated with a high degree of morbidity and mortality, usually related to sepsis. Although the pathophysiology of this condition is poorly understood, it appears to be related to a derangement in calcium-phosphate metabolism. Thus, treatments have focused on the treatment of hyperparathyroidism albeit with poor results. More recently, sodium thiosulfate (STS) has emerged as a promising therapy following multiple case reports of marked disease regression following its use. As STS is a strong acid, metabolic acidosis has been described following its administration, although relatively mild in degree. We report a case of a patient with calciphylaxis who repeatedly developed a severe anion gap metabolic acidosis following each dose of STS requiring a significant reduction in the dose.

Effects of high blood flow and high pre-dilution replacement fluid rates on small solute clearances in hemofiltration.

BACKGROUND/AIMS: In pre-dilution hemofiltration (HF), solute clearance is less than the HF rate. While the amount of this loss is predictable, it has not been validated in high-volume HF associated with high blood flow rates. METHODS: Using isovolemic pre-dilution HF, we studied small solute clearances using combinations of blood flow (Q(B); 150, 250, 350, 450 ml/min) and replacement fluid (RF) flow (Q(RF); 2, 4, 6 l/h) to determine clearance losses we entitled 'measured efficiency' (E(M)). E(M) was compared to predicted efficiency (E(P)) = (Q(B)/Q(B) + Q(RF)). RESULTS: Pre-dilution produced E(M) values of 61-93%. Increases in Q(B) for any Q(RF) and decreases in Q(RF) for any Q(B) increased E(M) over a wide range of Q(B) and Q(RF). E(P) was equivalent to E(M). CONCLUSION: In high-volume pre-dilution HF, E(P) can be used to determine E(M) across a broad range of Q(B) and Q(RF) values. Higher Q(RF) requires higher Q(B) to minimize the attenuating effects of pre-dilution on clearance.

Use of Intravenous Gadolinium-Based Contrast Media in Patients With Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Inaugural consensus statements were developed and endorsed by the American College of Radiology (ACR) and National Kidney Foundation to improve and standardize the care of patients with kidney disease who have indication(s) to receive ACR-designated group II or group III intravenous gadolinium-based contrast media (GBCM). The risk of nephrogenic systemic fibrosis (NSF) from group II GBCM in patients with advanced kidney disease is thought to be very low (zero events following 4931 administrations to patients with estimated glomerular filtration rate [eGFR] <30 mL/min per 1.73 m2; upper bounds of the 95% confidence intervals: 0.07% overall, 0.2% for stage 5D chronic kidney disease [CKD], 0.5% for stage 5 CKD and no dialysis). No unconfounded cases of NSF have been reported for the only available group III GBCM (gadoxetate disodium). Depending on the clinical indication, the potential harms of delaying or withholding group II or group III GBCM for an MRI in a patient with acute kidney injury or eGFR less than 30 mL/min per 1.73 m2 should be balanced against and may outweigh the risk of NSF. Dialysis initiation or alteration is likely unnecessary based on group II or group III GBCM administration.

Use of Intravenous Iodinated Contrast Media in Patients With Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Intravenous iodinated contrast media are commonly used with CT to evaluate disease and to determine treatment response. The risk of acute kidney injury (AKI) developing in patients with reduced kidney function following exposure to intravenous iodinated contrast media has been overstated. This is due primarily to historic lack of control groups sufficient to separate contrast-induced AKI (CI-AKI; ie, AKI caused by contrast media administration) from contrast-associated AKI (CA-AKI; ie, AKI coincident to contrast media administration). Although the true risk of CI-AKI remains uncertain for patients with severe kidney disease, prophylaxis with intravenous normal saline is indicated for patients who have AKI or an estimated glomerular filtration rate less than 30 mL/min/1.73 m2 who are not undergoing maintenance dialysis. In individual high-risk circumstances, prophylaxis may be considered in patients with an estimated glomerular filtration rate of 30-44 mL/min/1.73 m2 at the discretion of the ordering clinician.

Accelerated venovenous hemofiltration: early technical and clinical experience.

BACKGROUND: Renal replacement therapies other than intermittent hemodialysis are often required in hemodynamically unstable patients. Continuous renal replacement therapies use a slow blood flow rate, necessitating anticoagulation and prolonged treatment times that may create difficulties with staffing and limit patient diagnostic and therapeutic procedures. We developed an alternative strategy based on a higher blood flow rate that allows increased rates of hemofiltration, no anticoagulation, and a shorter ("accelerated") treatment period. We report our technical and clinical experience with accelerated venovenous hemofiltration (AVVH). STUDY DESIGN: Case series. SETTING & PARTICIPANTS: Hemodynamically unstable patients requiring renal replacement therapy in the medical or surgical intensive care unit of an academic medial center. OUTCOMES & MEASUREMENTS: Achieved dose, blood flow rate, mean arterial pressure, serum chemistry test results, patient weight, filter clotting, and patient survival. RESULTS: 100 patients received 457 AVVH treatments (average, 4.1 treatments/patient during 5.6 days). Mean Acute Physiology, Age, and Chronic Health Evaluation II score was 24 +/- 7.1. Treatment consisted of 36 L of predilution hemofiltration during 9 hours. Mean blood flow was 362 mL/min, and net fluid removal was 2.5 L/treatment. Anticoagulation was not used and filter clotting was seen in only 3.3% of treatments. 86% of patients received the prescribed dose. Pre- and post-AVVH chemistry test results showed a significant decrease in blood urea nitrogen (from 69.6 +/- 24.8 to 50.7 +/- 22.0 mg/dL) and serum creatinine levels (from 4.3 +/- 2.0 to 2.9 +/- 1.3 mg/dL). Weight was decreased significantly (from 98.8 +/- 26.4 to 93.4 +/- 23.1 kg). Pre- and post-AVVH mean arterial pressure comparison showed an increase from 72.8 +/- 13.6 to 74.4 +/- 15.2 mm Hg. Patient survival rate was 53%. LIMITATIONS: Retrospective analysis, absence of a comparison group. CONCLUSION: AVVH is an alternate renal replacement therapy for patients in the intensive care unit and appears to provide adequate volume and solute control without the need for anticoagulation. The shorter treatment period offers flexibility for staffing and other patient diagnostic and therapeutic procedures.

A health economic analysis of screening and optimal treatment of nephropathy in patients with type 2 diabetes and hypertension in the USA.

BACKGROUND: Nephropathy is an indicator of end-organ damage and is a strong predictor of an increased risk of cardiovascular disease and death in patients with diabetes. Screening can lead to early identification and treatment, both of which incur costs. However, identification and treatment may slow or prevent progression to a more expensive stage of the disease and thus may save money. We assessed the health economic impact of screening for nephropathy (microalbuminuria and overt nephropathy) followed by optimal renoprotective-based antihypertensive therapy in a US setting. METHODS: A Markov model simulated the lifetime impact of screening with semi-quantitative urine dipsticks in a primary care setting of hypertensive patients with type 2 diabetes and subsequent treatment with irbesartan 300 mg in patients identified as having nephropathy. Progression from no nephropathy to end-stage renal disease (ESRD) was simulated. Probabilities, utilities, medication and ESRD treatment costs came from published sources. Clinical outcomes and direct medical costs were projected. Second order Monte Carlo simulation was used to account for uncertainty in multiple parameters. Annual discount rates of 3% were used where appropriate. RESULTS: Screening, followed by optimized treatment, led to a 44% reduction in the cumulative incidence of ESRD and improvements in non-discounted life expectancy of 0.25 +/- 0.22 years/patient (mean +/- SD). Quality-adjusted life expectancy was improved by 0.18 +/- 0.15 quality-adjusted life years (QALYs)/patient and direct costs increased by $244 +/- 3499/patient. The incremental cost-effectiveness ratio was $20 011 per QALY gained for screening and optimized treatment versus no screening. There was a 77% probability that screening and optimized therapy would be considered cost effective with a willingness to pay a threshold of $50 000. CONCLUSION: In patients with type 2 diabetes and hypertension, screening for nephropathy and treatment with a renoprotective-based antihypertensive agent was projected to improve patient outcomes and represent excellent value in a US setting.