Dimercaptosuccinic acid (DMSA) renal scan in the evaluation of hypertension in children

Yield of diagnostic testing in evaluating etiology and end organ effects of pediatric hypertension

BACKGROUND

Current recommendations regarding the utility of diagnostic investigations for pediatric hypertension are based on limited evidence, leading to wide practice variation. The objective of this study was to characterize the cohort of children that may benefit from secondary hypertension workup, and determine the diagnostic yield of investigations.

METHODS

This was a single-center, retrospective cohort study of 169 children aged 1-18 years referred between 2000 and 2015, to a tertiary pediatric nephrology center in Canada, for evaluation of hypertension. The number of investigations completed, abnormal findings, and diagnostic findings that helped establish hypertension etiology was determined.

RESULTS

56 children were diagnosed with primary and 72 children with secondary hypertension in the outpatient setting. Secondary hypertension was predominant at all ages except for obese adolescents ≥ 12 years. Half of children with traditional risk factors for primary hypertension, including obesity, were diagnosed with secondary hypertension. Kidney ultrasound had the highest yield of diagnostic results (19.8%), with no difference in yield between age groups (P = 0.19). Lipid profile had a high yield of abnormal results (25.4%) as part of cardiovascular risk assessment but was only abnormal in overweight/obese children. Echocardiogram had a high yield for identification of target-organ effects in hypertensive children (33.3%).

CONCLUSION

A simplified secondary hypertension workup should be considered for all hypertensive children and adolescents. High yield investigations include a kidney ultrasound, lipid profile for overweight/obese children, and echocardiograms for assessment of target-organ damage. Further testing could be considered based on results of initial investigations for the most cost-effective management. A higher resolution version of the Graphical abstract is available as Supplementary information.

Primary Vesicoureteral Reflux and Renal Scarring

Vesicoureteral reflux (VUR) is the commonest congenital anomaly of urinary tract in children. It is mostly diagnosed after a urinary tract infection or during evaluation for congenital anomalies of the kidney and urinary tract. High-grade VUR, recurrent pyelonephritis, and delayed initiation of antibiotic treatment are important risk factors for renal scarring. The management of VUR depends on multiple factors and may include surveillance only or antimicrobial prophylaxis; very few patients with VUR need surgical correction. Patients with renal scarring should be monitored for hypertension and those with significant scarring should also be monitored for proteinuria and chronic kidney disease.

Do children with solitary or hypofunctioning kidney have the same prevalence for masked hypertension?

BACKGROUND

Having a low nephron number is a well-known risk factor for hypertension. There is an inverse relationship between the filtration surface area and systemic hypertension. A significant percentage of masked hypertension can be detected in children with nephron loss by ambulatory blood pressure monitoring (ABPM).

METHODS

We prospectively investigated ABPM results of children having reduced kidney mass with normal office blood pressures (BPs) and kidney function. Forty-three children with congenital solitary kidney (group 1), 11 children with acquired solitary kidney (group 2), and 76 children with hypofunctioning kidney (group 3) were compared with age, gender, and BMI-matched healthy control group (group 4). The dietary salt intake of 76 patients was evaluated as salt equivalent (g/day). The primary endpoint was change from baseline in mean 24-h ABPM variables and the proportion of patients with masked hypertension when assessed by ABPM.

RESULTS

The masked hypertension ratio of all patients was 12.3% when assessed with ABPM. Night hypertension was significantly higher in all patient groups than in the control group (p = 0.01). Diastolic BP loads of groups 1 and 3 were higher than in controls (p = 0.024). Systolic BP loads were higher only in group 1 than in the control group (p = 0.003). The dietary salt equivalent of patients in group 1 correlated positively with 24-h SBP and mean arterial pressure (MAP) values. Patients with excessive dietary salt intake in group 1 had a significantly higher diastolic BP load than those without excessive salt intake in group 1 (p = 0.002).

CONCLUSIONS

Masked hypertension can be seen in children with a solitary kidney or when one of the kidneys is hypofunctioning. Systolic BP loads are higher in children with congenital solitary kidney, and salt intake correlates with systolic BP profiles especially in those. Our results suggest that being born with a congenital solitary kidney increases predisposition to hypertension and salt sensitivity.

Contemporary Management of Urinary Tract Infection in Children

Urinary tract infection (UTI) is common in children, and girls are at a significantly higher risk, as compared to boys, except in early infancy. Most cases are caused by Escherichia coli Collection of an uncontaminated urine specimen is essential for accurate diagnosis. Oral antibiotic therapy for 7 to 10 days is adequate for uncomplicated cases that respond well to the treatment. A renal ultrasound examination is advised in all young children with first febrile UTI and in older children with recurrent UTI. Most children with first febrile UTI do not need a voiding cystourethrogram; it may be considered after the first UTI in children with abnormal renal and bladder ultrasound examination or a UTI caused by atypical pathogen, complex clinical course, or known renal scarring. Long-term antibiotic prophylaxis is used selectively in high-risk patients. Few patients diagnosed with vesicoureteral reflux after a UTI need surgical correction. The most consequential long-term complication of acute pyelonephritis is renal scarring, which may increase the risk of hypertension or chronic kidney disease later in life. Treatment of acute pyelonephritis with an appropriate antibiotic within 48 hours of fever onset and prevention of recurrent UTI lowers the risk of renal scarring. Pathogens causing UTI are increasingly becoming resistant to commonly used antibiotics, and their indiscriminate use in doubtful cases of UTI must be discouraged.

Dimercaptosuccinic acid scintigraphy vs. ultrasound for renal parenchymal defects in children

INTRODUCTION

Dimercaptosuccinic acid (DMSA) scintigraphy is the gold standard in the evaluation of renal parenchymal defects and is widely used in the pediatric population. As more recent ultrasound equipment was purchased at our tertiary pediatric centre, our objective was to evaluate if renal ultrasound (US) results are equivalent or sufficient when compared to DMSA scintigraphy in the assessment of renal anomalies.

METHODS

The charts of all 463 patients who underwent DMSA scintigraphy between January 2009 and May 2014 at our pediatric tertiary centre were reviewed. The objective was to look for correlation between US and DMSA scan results for renal scars/dysplasia. A hundred and sixty pediatric patients followed with US and DMSA scan for a total of 285 renal units remained for evaluation after exclusions. Timing of the exams, urinary tract infection (UTI), and indication for imaging were reviewed. Results with older (105 patients) and newer (55 patients) US equipment were compared.

RESULTS

Among the 285 renal units evaluated, 39 (14%) had renal parenchymal defects shown by US and 87 (31%) by DMSA scintigraphy (sensitivity 36%, specificity 96%). The DMSA scan was normal for eight abnormal kidneys (3%) on US. The results were not statistically significant when compared to exams performed with newer or older US machines.

CONCLUSIONS

At our institution, US data are not sensitive enough to give reliable information about renal parenchymal defects, even with newer equipment. DMSA scintigraphy still remains mandatory for the evaluation of renal anomalies, but could be optional if the US exam indicates parenchymal defects.

Evolution of blood pressure in children with congenital and acquired solitary functioning kidney

Background

It is not yet clear if blood pressure and renal function changes evolve differently in children with a congenital or acquired solitary functioning kidney. This study aims to assess if there are any differences between these two types of solitary kidney patients.

Methods

Current research is a retrospective study assessing the evolution of glomerular filtration rate, proteinuria, and blood pressure in clinical records of 55 children with a solitary functioning kidney (37 congenital and 18 acquired). We used the medical records of children who had been assisted, in our unit of pediatric nephrology, for a period of 14 years (168 months), from the time of diagnosis, between January/1997 and December/2015.

Results

During the study period, glomerular filtration rate (T0 128.89 ± 32.24 vs T14 118.51 ± 34.45 ml/min/1.73 m², p NS) and proteinuria (T0 85.14 ± 83.13 vs T14 159.03 ± 234.66 mg/m²/die, p NS) demonstrated no significant change. However, after 14 years of follow-up 76.4% of patients had increased levels of arterial hypertension with values over the 90th percentile for gender, age, and height. Specifically, children with an acquired solitary functioning kidney mainly developed hypertension [T0 2/17 (12%) vs T14 9/17 (52.9%) p < 0.025], whereas children with a congenital solitary functioning kidney mainly developed pre-hypertension [T0 3/38 (7.9%) vs T14 17/38 (44.7%) p < 0.0005].

Conclusions

The renal function of children with solitary functioning kidneys remains stable during a follow-up of 14 years. However, these children should be carefully monitored for their tendency to develop arterial blood pressure greater than the 90th percentile for gender, age, and height.

Evaluation of hypertension in children

Hypertension is an important public health problem, and increasingly children are being diagnosed with primary hypertension. As the list of secondary causes of hypertension is extensive, pediatric practitioners increasingly need to decide on investigations needed for evaluating children presenting with high blood pressure. The differentiation between primary and secondary hypertension is paramount to understanding this important health issue, since many forms of secondary hypertension require specific treatment. The review evaluates the current available guidelines and practice patterns for evaluating children with elevated blood pressure. The review also aims to provide a framework for cost-effective evaluation strategies for children with elevated blood pressure based on current recommendations and evidence.

Prediction of primary vs secondary hypertension in children

Despite current guidelines, variability exists in the workup of hypertensive children due to physician preferences. The study evaluates primary vs secondary hypertension diagnosis from investigations routinely performed in hypertensive children. This retrospective study included children 5 to 19 years with primary and secondary hypertension. The proportions of abnormal laboratory and imaging tests were compared between primary and secondary hypertension groups. Risk factors for primary vs secondary hypertension were evaluated by logistic regression and likelihood function analysis. Patients with secondary hypertension were younger (5-12 years) and had a higher proportion of abnormal creatinine, renal ultrasound, and echocardiogram findings. There was no significant difference in abnormal results of thyroid function, urine catecholamines, plasma renin, and aldosterone. Abnormal renal ultrasound findings and age were predictors of secondary hypertension by regression and likelihood function analysis. Children aged 5 to 12 years with abnormal renal ultrasound findings and high diastolic blood pressures are at higher risk for secondary hypertension that requires detailed evaluation.

Managing urinary tract infections

Urinary tract infections (UTI) are common in childhood. Presence of pyuria and bacteriuria in an appropriately collected urine sample are diagnostic of UTI. The risk of UTI is increased with an underlying urological abnormality such as vesicoureteral reflux, constipation, and voiding dysfunction. Patients with acute pyelonephritis are at risk of renal scarring and subsequent complications such as hypertension, proteinuria with and without FSGS, pregnancy-related complications and even end-stage renal failure. The relevance and the sequence of the renal imaging following initial UTI, and the role of antimicrobial prophylaxis and surgical intervention are currently undergoing an intense debate. Prompt treatment of UTI and appropriate follow-up of those at increased risk of recurrence and/or renal scarring are important.

Vesicoureteral reflux and reflux nephropathy

Primary vesicoureteral reflux (VUR) is the commonest congenital urological abnormality in children, which has been associated with an increased risk of urinary tract infection (UTI) and renal scarring, also called reflux nephropathy (RN). In children, RN is diagnosed mostly after UTI (acquired RN) or during follow-up for antenatally diagnosed hydronephrosis with no prior UTI (congenital RN). The acquired RN is more common in female children, whereas the congenital RN is more common in male children. This observation in children might help explain the differences in the clinical presentation of RN in adults, with males presenting mostly with hypertension, proteinuria, and progressive renal failure as compared with females who present mostly with recurrent UTI and have a better outcome. Known risk factors for RN include the severity of VUR, recurrent UTI, and bladder-bowel dysfunction; younger age and delay in treatment of UTI are believed to be other risk factors. Management of VUR is controversial and includes antimicrobial prophylaxis, surgical intervention, or surveillance only. No evidence-based guidelines exist for appropriate follow-up of patients with RN.

Primary versus secondary hypertension in children followed up at an outpatient tertiary unit

Childhood hypertension has classically been recognized as a secondary disease. However, primary hypertension also occurs in children. The aim of this study was to compare clinical features of pediatric patients with elevated blood pressure, which were referred to an outpatient tertiary unit, and to detect variables associated with the identification of primary hypertension. The records of 220 patients with hypertension followed between 1996 and 2006 were analyzed. The variable of interest was primary hypertension. Logistic regression analysis was applied to identify clinical variables that were independently associated with primary hypertension. Of 220 patients, 33 (15%) had primary hypertension, and 187 (85%) exhibited secondary hypertension. No statistically significant differences were detected in gender, race, age at diagnosis, and systolic/diastolic blood pressure levels between both groups. After adjustment, four variables at baseline remained independently associated with primary hypertension: absence of signs/symptoms (OR 18.87, 95% CI 6.32-56.29), normal serum creatinine (OR 0.02, 95% CI 0.00-0.27), family history of hypertension (OR 3.03, 95% CI 1.04-8.79), and elevated body weight (OR 1.06, 95% CI 1.02-1.10). The absence of signs/symptoms, normal serum creatinine, family history of hypertension, and overweight/obesity at admission are clues to diagnose primary hypertension in childhood.

Treatment of systemic hypertension in children and adolescents

PURPOSE OF REVIEW

This review aims to update the practitioner in recent developments in the treatment of hypertension in children and adolescents.

RECENT FINDINGS

In the last years, the treatment of hypertension in children and adolescents has been characterized by an improvement in the definition of hypertension and the more widespread use of the 24-h blood pressure monitor to define the hypertension pattern and assess efficacy of the therapy. A few studies on the use of converting enzyme inhibitors and angiotensin II receptor blocker emphasizing doses, efficacy, and side effects have been published. Of special interest is the tantalizing hypothesis on the role of uric acid in essential hypertension and the practical application of the use of allopurinol as monotherapy for this condition.

SUMMARY

The authors aim to convey the need to define the blood pressure pattern in these patients before any type of therapy is started and the titration of medications according to the pathophysiologic mechanisms involved.

Update on childhood urinary tract infection and vesicoureteral reflux

Urinary tract infection (UTI) is a leading cause of serious bacterial infection in young children. Vesicoureteral reflux (VUR), a common pediatric urologic disorder, is believed to predispose to UTI, and both are associated with renal scarring. The complex interaction of bacterial virulence factors and host defense mechanisms influence renal damage. However, some renal parenchymal abnormalities associated with VUR are noninfectious in origin. Long-term, renal parenchymal injury may be associated with hypertension, pregnancy complications, proteinuria, and renal insufficiency. Optimal management of VUR and UTI is controversial because of the paucity of appropriate randomized controlled trials; there is a need for well-designed studies. The recently launched Randomized Intervention for children with VesicoUreteral Reflux (RIVUR) study hopefully will provide insight into the role of antimicrobial prophylaxis of UTI in children with VUR.

Imaging studies for first urinary tract infection in infants less than 6 months old: can they be more selective?

This retrospective study aimed to evaluate the applicability of the selective approach of imaging infants < 6 months old with urinary tract infection (UTI) according to the UTI guidelines of the National Institute for Health and Clinical Excellence (NICE) 2007. Infants < 6 months old with their first UTI from January 2001 to December 2006 having undergone an ultrasound examination of the urinary tract, a micturating cystourethrogram, and a late di-mercaptosuccinic acid (DMSA) scan, were included. Their condition was evaluated against a set of risk features according to the UTI guidelines. Those having any one of these were classified as atypical and those having none as typical. There were 134 infants reviewed, with a typical (98 infants) to atypical (36 infants) ratio of 2.7 to 1. Girls were found to be relatively more represented in the atypical group [male (M):female (F) = 1.3:1] than in the typical group (M:F = 4.4:1) (P < 0.004). There were significantly more infants with abnormal micturating voiding cystourethrograms (MCUGs) (P = 0.007), more refluxing ureters (P < 0.001) and more significant vesico-ureteral reflux (VUR) (>/= grade III) (P = 0.013) in the atypical group than in the typical group; while there was no significant difference in ultrasound (US) and DMSA scan findings between the two groups. In the atypical group there was no difference in imaging studies (and, thus, the results) between the conventional practice and the NICE UTI recommendation. In the typical group, if the recommendations of the guidelines had been followed (i.e. only those with abnormal US would have been further investigated), 25 refluxing ureters and 22 scarred kidneys would have been left undiagnosed. In conclusion, application of the suggested selective imaging approach would leave a significant number of VUR and renal scars undiagnosed, and it may not be an optimal practice for infants less than 6 months old with their first UTI. The best approach remains to be clarified.

Early switch to oral versus intravenous antimicrobial treatment for hospitalized patients with acute pyelonephritis: a systematic review of randomized controlled trials

BACKGROUND

Acute pyelonephritis is a common infection with significant morbidity and mortality, particularly in pediatric populations. Early-switch strategies (from intravenous to oral treatment) may be an acceptable or even preferred option in the treatment of patients with acute pyelonephritis in terms of effectiveness and safety and can also reduce the economical burden associated with pyelonephritis.

OBJECTIVE

We sought to evaluate the effectiveness and safety of early-switch strategies in hospitalized patients with acute uncomplicated pyelonephritis.

METHODS

We searched in PubMed, Cochrane Central Register of Controlled Trials, and Scopus to identify randomized controlled trials (RCTs) that compared intravenous antibiotic regimens to regimens including an early switch to oral (after initial intravenous) treatment.

RESULTS

Eight RCTs (6 in children) were eligible for inclusion. In 5 RCTs the intravenous antibiotic treatment arms were not switched to oral treatment until the end of the study while in the remaining 3 RCTs the intravenous arms were switched late to oral treatment (after 5-10 days). Data regarding the incidence of renal scars, microbiological eradication, clinical cure, reinfection, persistence of acute pyelonephritis, and adverse events were provided in 4 (all pediatric trials), 6 (4 pediatric), 4 (2 pediatric), 5 (3 pediatric), 3 (1 pediatric), and 5 RCTs (3 pediatric), respectively. There were no differences regarding the above outcomes between the two compared treatment regimens in either pediatric or adult populations.

CONCLUSION

Early switch to oral antibiotic strategies seem to be as effective and safe as intravenous regimens for the treatment of hospitalized patients with acute pyelonephritis. These findings suggest that there is probably a potential to decrease the duration of intravenous treatment by 4-11 days in hospitalized patients with acute pyelonephritis without compromising their outcomes.