Congenital Solitary Functioning Kidney Research Articles

Congenital solitary functioning kidney: evaluations to do which, when, and how

Congenital solitary functioning kidney (CSFK) is characterized by an anatomical or functional absence of one kidney from birth. When suspected on perinatal ultrasonography (US), repeat US after birth should be performed for confirmation. Although postnatal 99mTc-dimercaptosuccinic acid scintigraphy (DMSA scan) is the gold standard for confirming CSFK, it carries the risk of radiation exposure; US alone is sufficient when performed by an experienced radiologist. One-third of patients with CSFK have additional congenital anomalies of the kidney and urinary tract at the solitary functioning kidney, the most common of which is vesicoureteral reflux. As evidence regarding vesicoureteral reflux with normal kidney US is correlated with significant urinary tract infection is lacking, voiding cystourethrogram may be considered in patients with CSFK with abnormal US findings. Furthermore, approximately 30% of patients with CSFK have extrarenal malformations. Moreover, up to 10% of them have syndromic features. In particular, examining for female genitalia malformations, which can have potential for complications from untreated obstructive malformations, is important. In conclusion, DMSA scan and voiding cystourethrogram are not necessary for all patients with CSFK, and the risk of each patient should be assessed to determine which test is needed during follow-up. The presence of extrarenal manifestations should also always be considered.

Müllerian anomalies in girls with congenital solitary kidney

BackgroundThe prevalence of Müllerian anomalies (MA) among patients with congenital solitary functioning kidney (SFK) is not well defined. A delay in diagnosis of obstructive MA can increase the risk of poor clinical outcomes. This study describes the prevalence of MA in patients with congenital SFK.MethodsA retrospective review was performed of patients within the Nationwide Children’s Hospital system with ICD9 or ICD10 diagnostic codes for congenital SFK defined as either unilateral renal agenesis (URA) or multicystic dysplastic kidney (MCDK) and confirmed by chart review. Patients with complex urogenital pathology were excluded. Renal anomaly, MA, reason for and type of pelvic evaluation, and age of diagnosis of anomalies were evaluated.ResultsCongenital SFK occurred in 431 girls due to URA (209) or MCDK (222). Pelvic evaluation, most commonly by ultrasound for evaluation of abdominal pain or dysmenorrhea, occurred in 115 patients leading to MA diagnosis in 60 instances. Among 221 patients ages 10 years and older, 104 underwent pelvic evaluation and 52 were diagnosed with an MA of which 20 were obstructive. Isolated uterine or combined uterine and vaginal anomalies were the most common MA. MA were five-fold more common in patients with URA compared to MCDK. In 75% of patients, the SFK was diagnosed prior to the MA.ConclusionsThe prevalence of MA in patients with congenital SFK was 24% among those age 10 years or older, and 38% were obstructive. This justifies routine screening pelvic ultrasound in girls with congenital SFK to improve early diagnosis.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information

Genetic and environmental factors driving congenital solitary functioning kidney.

Congenital solitary functioning kidney (CSFK) is an anomaly predisposing to hypertension, albuminuria and chronic kidney disease. Its aetiology is complex and includes genetic and environmental factors. The role of gene-environment interactions (G×E), although relevant for other congenital anomalies, has not yet been investigated. Therefore, we performed a genome-wide G×E analysis with six preselected environmental factors to explore the role of these interactions in the aetiology of CSFK. In the AGORA (Aetiologic research into Genetic and Occupational/environmental Risk factors for Anomalies in children) data- and biobank, genome-wide single-nucleotide variant (SNV) data and questionnaire data on prenatal exposure to environmental risk factors were available for 381 CSFK patients and 598 healthy controls. Using a two-step strategy, we first selected independent significant SNVs associated with one of the six environmental risk factors. These SNVs were subsequently tested in G×E analyses using logistic regression models, with Bonferroni-corrected P-value thresholds based on the number of SNVs selected in step one. In step one, 7-40 SNVs were selected per environmental factor, of which only rs3098698 reached statistical significance (P=.0016, Bonferroni-corrected threshold 0.0045) for interaction in step two. The interaction between maternal overweight and this SNV, which results in lower expression of the Arylsulfatase B (ARSB) gene, could be explained by lower insulin receptor activity in children heterozygous for rs3098698. Eight other G×E interactions had a P-value <.05, of which two were biologically plausible and warrant further study. Interactions between genetic and environmental factors may contribute to the aetiology of CSFK. To better determine their role, large studies combining data on genetic and environmental risk factors are warranted.

GFR measurements and ultrasound findings in 154 children with a congenital solitary functioning kidney

Multicystic dysplastic kidney (MCDK) and unilateral renal agenesis (URA) are the most common reasons for a congenital solitary functioning kidney (SFK). We aimed to assess the presence of abnormalities in the congenital SFK and evaluate kidney function using chrome EDTA (CrEDTA) measurements. We retrospectively reviewed the medical records of 154 children with MCDK and URA in the period from 2005 to 2022 to analyze results from ultrasound scans and CrEDTA glomerular filtration rate (GFR) examinations. Of 154 children with a solitary kidney due to MCDK (62%) or URA (38%), abnormalities on the congenital SFK were found in 13 children (8%). The abnormalities spontaneously resolved in 6 children (46%). The most common abnormality was hydronephrosis. Compensatory hypertrophy was found in 17% of the children within the first 6 months of life. 116 children (90%) had a standard GFR (sdGFR) above 75% of expected for the age. Out of those with a sdGFR below 75% of expected, 3 (23%) had abnormalities in the congenital SFK. There was no difference in sdGFR between children with MCDK and URA. Our study is the first using CrEDTA for GFR measurements and suggests that most children with a congenital SFK due to MCDK or URA have a kidney function within expected for the age. Compensatory hypertrophy of the SFK is found in a minority of children within the first six months of life, suggesting that this process is developing over time. The prevalence of abnormalities in the SFK seems low, however those with abnormalities (e.g. hydronephrosis) are at higher risk of reduced sdGFR.

Environmental and parental risk factors for congenital solitary functioning kidney — a case–control study

BackgroundThe etiology of congenital solitary functioning kidney (CSFK) is largely unknown but likely includes various risk factors. We performed a case–control study to compare exposure to environmental and parental risk factors during embryonic kidney development between children with CSFK and healthy controls.MethodsWe included 434 children with CSFK and 1302 healthy controls from the AGORA data- and biobank matched on year of birth. Exposure to potential risk factors was investigated using parental questionnaire data. Crude and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were estimated for each potential risk factor. Multiple imputation was used to deal with missing values. Confounders for each potential risk factor were selected using directed acyclic graphs.ResultsMaternal stress was newly identified as a risk factor for CSFK (aOR 2.1, 95% CI 1.2–3.5). Known associations with conception using in vitro fertilization/intracytoplasmic sperm injection (aOR 1.8, 95% CI 1.0–3.2), maternal infections during pregnancy (aOR 2.5, 95% CI 1.4–4.7), smoking during pregnancy (aOR 1.4, 95% CI 1.0–2.0), and parental CAKUT (aOR 6.6, 95% CI 2.9–15.1) were confirmed, but previous associations with diabetes and obesity could not be replicated. Folic acid supplement use and younger maternal age seemed to reduce the risk of CSFK (aORs 0.7, 95% CI 0.5–1.0, and 0.8, 95% CI 0.6–1.0, respectively).ConclusionsEnvironmental and parental risk factors are likely to be involved in the development of CSFK and future studies should combine genetic, environmental, and gene-environment interaction analyses. Women wanting to become pregnant should consider optimizing their health and lifestyle.Graphical abstractA higher-resolution version of the Graphical abstract is available as Supplementary information

A Genome-Wide Association Study into the Aetiology of Congenital Solitary Functioning Kidney.

Congenital solitary functioning kidney (CSFK) is a birth defect that occurs in 1:1500 children and predisposes them to kidney injury. Its aetiology is likely multifactorial. In addition to known monogenic causes and environmental risk factors, common genetic variation may contribute to susceptibility to CSFK. We performed a genome-wide association study among 452 patients with CSFK and two control groups of 669 healthy children and 5363 unaffected adults. Variants in two loci reached the genome-wide significance threshold of 5 × 10-8, and variants in 30 loci reached the suggestive significance threshold of 1 × 10-5. Of these, an identified locus with lead single nucleotide variant (SNV) rs140804918 (odds ratio 3.1, p-value = 1.4 × 10-8) on chromosome 7 was most promising due to its close proximity to HGF, a gene known to be involved in kidney development. Based on their known molecular functions, both KCTD20 and STK38 could explain the suggestive significant association with lead SNV rs148413365 on chromosome 6. Our findings need replication in an independent cohort of CSFK patients before they can be established definitively. However, our analysis suggests that common variants play a role in CSFK aetiology. Future research could enhance our understanding of the molecular mechanisms involved.

Uncovering risk factors for kidney injury in children with a solitary functioning kidney

Children with a solitary functioning kidney (SFK) have an increased risk of kidney injury. The exact risk of and risk factors for kidney injury remain unknown, which impedes personalized care. Here, we recruited a nationwide multicenter cohort of 944 patients with SFK to get more insight into this by consenting patients born in 1993-2020 and diagnosed with congenital or acquired SFK before adulthood. The median follow-up was 12.8 years and four indications of kidney injury were studied: urine protein-creatinine ratios, blood pressure, estimated glomerular filtration rate and use of anti-hypertensive/proteinuric medication. For each indicator except medication use, separate cut-off values for any injury and severe injury were used. Survival analyses indicated that at 18 years of age, any or severe kidney injury were present in 75% and 39% of patients with congenital SFK, respectively. Risk factors for kidney injury included kidney agenesis as cause of the SFK, anomalies in the SFK, and high body mass index at last follow-up. Kidney agenesis and being overweight were specifically associated with proteinuria and high blood pressure, whereas anomalies in the SFK were associated with reduced estimated glomerular filtration rates. The high prevalence of kidney injury in patients with SFK emphasizes the need for long-term follow-up, in which lifestyle is an important topic to address. More research into the etiological role of risk factors will help to translate our findings into individualized care strategies. Thus, our study shows that a significant proportion of children with SFK will develop kidney injury over time.

Early Renal Ultrasound in Patients with Congenital Solitary Kidney Can Guide Follow-Up Strategy Reducing Costs While Keeping Long-Term Prognostic Information.

We aimed to evaluate the prognostic value of renal length (RL) > 2 standard deviation scores (SDS) measured by renal ultrasound (RUS), across infancy, childhood and adolescence, in identifying which patients with congenital solitary functioning kidney (CSFK) are at lower risk of developing kidney injury (KI). We also estimated the cost saving of integrating the current follow-up protocols with an early RUS algorithm (ERUSA). Fifty-six CSFK adult patients who were 1–3 months old at first observation of undergoing RUS were enrolled. KI was defined by hypertension and/or proteinuria and/or declined renal function. ERUSA was assessed by early (at 1–3 months of life) RUS and was retrospectively tested in our patients. ERUSA establishes that patients with RL > 2SDS at early RUS do not undergo further follow-ups. The others undergo another RUS at 1 year of age along with follow-ups according with current protocols, with the exception of RUS which could be no longer performed. Direct and indirect costs were calculated for each analysed protocol and the cost saving of applying ERUSA was calculated. None of the patients with early RL > 2SDS presented KI in adulthood. A RL > 2SDS was predictive of absence of KI only at 1–3 months (OR = infinity) and 1 year of age (OR = 0.13; 95%CI: 0.03–0.66; p = 0.01). ERUSA provided a total cost-sparing ranging from 38.6% to 55.3% among the analysed follow-up protocols. With ERUSA, no patients developing KI in adulthood were missed. In conclusion, only a RL > 2SDS at 1–3 months and 1 year of age predicted good prognosis in young adulthood. ERUSA can guide a cost-sparing follow-up strategy in CSFK patients while maintaining important long-term information.

Evolution of congenital anomalies of urinary tract in children with and without solitary kidney.

We hypothesized that children with congenital solitary functioning kidney (CSFK) present forms of congenital urinary tract anomalies (CUTA) with higher chance of spontaneous resolution compared with patients with two kidneys. We retrospectively selected 75 consecutive children with CUTA of the CSFK and 75 matched patients with unilateral CUTA but without CSFK (controls) with prenatal suspicion of unilateral CUTA and early evaluation. We compared the spontaneous CUTA resolution and the prevalence of kidney injury between groups at last follow-up. Patients and controls were clustered under the categories of "severe" and "non-severe" CUTA. The mean age at first and last follow-up was 0.17 ± 0.07 and 8.5 ± 5.2 years. Compared with controls, patients with CSFK had lower prevalence of severe CUTA at first evaluation; lower prevalence of febrile urinary tract infections, need of surgical correction, and higher rate of spontaneous CUTA resolution during follow-up; and a similar prevalence of mild kidney injury at last follow-up. CSFK compared with controls presented higher cumulative proportion of spontaneous resolution from severe CUTA (100 vs 41.8%; p &lt; 0.001) and from the single CUTA sub-categories (severe vesicoureteral reflux, non-obstructive hydronephrosis, and megaureter). CSFK patients had lower prevalence of severe forms and better outcomes of their CUTA compared with controls. One-third of patients with congenital solitary functioning kidney (CSFK) present congenital urinary tract anomalies (CUTA) and manifest poorer outcomes compared with CSFK without CUTA. CSFK patients had lower prevalence of severe forms and better outcomes of their CUTA in spite of similar prevalence of kidney injury compared with controls. This adds evidence about disturbed nephrogenesis in CSFK patients and emboldens conservative management of many of their non-obstructive CUTA.

Prognosis of Children With a Congenital Solitary Functioning Kidney

Prognosis of Children With a Congenital Solitary Functioning Kidney

POS-394 SOLITARY FUNCITONING KIDNEY ACQUIRED EARLY IN LIFE IS NOT ASSOCIATED WITH REDUCED RENAL FUNCTIONAL RESERVE COMPARED WITH CONGENITAL SOLITARY FUNCTIONING KIDNEY IN SHEEP

Children born with a solitary functioning kidney (SFK) can develop hypertension and kidney injury. Children who acquire a SFK early in childhood (early acquired; EA-SFK) have a greater incidence of kidney injury compared with those with a congenital SFK (C-SFK). The mechanisms underlying these differences are not well understood. The C-SFK undergoes compensatory nephron hyperplasia. Since no new nephrons form after birth in humans, the degree of nephron deficiency is greater in the EA-SFK compared with C-SFK. In both forms of SFK, the remaining kidney undergoes hypertrophy and increases glomerular filtration rate (GFR) to compensate for the loss of a kidney but this hyperfiltration can promote kidney injury. We hypothesized that owing to greater degree of nephron deficiency, the EA-SFK would undergo a greater a degree of hyperfiltration compared with C-SFK. Additionally, we hypothesized that owing to greater degree of basal hyperfiltration, in response to a challenge, EA-SFK would have a reduced capacity to increase renal functional reserve. Unilateral nephrectomy was performed in sheep fetus at 100 days of gestation (term-150 days; n=9) to induce C-SFK and in the 4-week-old lamb (n=8) to induce EA-SFK. Like the human, no new nephrons form after birth in the sheep. At 8 months of age, mean arterial pressure (MAP), GFR, and urinary protein excretion (UprotV) were measured during an hour baseline and during 120 minutes of a combined infusion of amino acid (0.065ml/kg/h) and dopamine (5µg/kg/min) (AA+DOPA) in conscious lambs. Basal MAP was ~10mmHg lower in the EA-SFK group compared with C-SFK (P=0.003) and basal UprotV was ~50% lower in the EA-SFK compared with C-SFK group (P=0.0003). Basal GFR was ~27% greater in the EA-SFK compared with C-SFK group. In response to AA+DOPA, MAP did not change but UprotV and GFR increased from baseline in both groups. The increase in GFR in EA-SFK group was ~21% greater than the C-SFK group (P=0.08) but the increase in UprotV was similar between the groups. EA-SFK group had higher basal GFR compared with C-SFK demonstrating evidence of hyperfiltration. However, this was not associated with a reduced capacity to increase GFR in response to a combined infusion of amino acid and dopamine. Longer term follow-up maybe needed to determine if the greater basal GFR observed in the EA-SFK group exacerbates kidney injury and causes loss of renal functional reserve overtime.

Renal function in children with a congenital solitary functioning kidney: A systematic review

Abnormal renal development that results in lack of function or development of one of two kidneys is known as congenital solitary functioning kidney (CSFK). Two well characterized sub-categories of CFSK are unilateral renal agenesis (URA) and multicystic dysplastic kidney (MCDK). This systematic review sought to evaluate the change in renal function in children ≤18 years old with a CSFK as a result of URA or MCDK. A literature search in MEDLINE and Embase was conducted (1946 to July 13, 2020). All relevant articles were retrieved and evaluated based on pre-selected criteria by two independent researchers. Data was then extracted from variables of interest and conflicts were resolved by a third researcher. The primary outcome was renal function, and the secondary outcomes were proteinuria and hypertension. Forty-five studies were included, of which 49% (n=22) were retrospective and/or 58% (n=26) were cohort studies. A combined total of 2148 and 885 patients were diagnosed with MCDK or URA, respectively. The proportion of children with worsened renal function at follow-up was found to be 8.4% (95% CI: 5.2%-13.4%). Among the studies reporting renal function as a group mean or median at follow-up, 84% (21/25) had a GFR/CrCl above 90 (mL/min/1.73m2/ml/min). In terms of secondary outcomes, the proportion of children with proteinuria and hypertension was found to be 10.1% (95% CI: 6.9%-14.6%) and 7.4% (95% CI: 5.0%-10.9%), respectively. The risk of developing proteinuria (10.1%), hypertension (7.4%), and/or worsened renal function (8.4%) for children with CFSK as a result of MCDK or URA is low. However, the level of evidence in the literature is weak. Further research is needed to identify the predisposing factors that may differentiate the small subset of children with CSFK at a higher risk of developing adverse renal outcomes.

Should we need more sensitive early diagnostic markers in children with congenital solitary functioning kidneys?

Should we need more sensitive early diagnostic markers in children with congenital solitary functioning kidneys?

P1813CLINICAL CHARACTERIZATION OF CONGENITAL SOLITARY FUNCTIONING KIDNEY IN CHILDREN

Abstract Background and Aims Congenital anomalies of the kidney and urinary tract (CAKUT) are the major cause of chronic kidney disease and end-stage kidney disease in childhood. Solitary functioning kidney (SFK) is part of the spectrum of CAKUT. Congenital SFK is mainly due to unilateral renal agenesis (URA) and multi-cystic dysplastic kidney (MCDK). With the implementation of routine fetal ultrasound screening, SFK is increasingly recognized before birth, significantly raising the number of patients referred to paediatric nephrology units for clinical monitoring during childhood. Understanding the pathophysiology of SFK is pivotal for guiding the clinical management and informing long-term outcome. However, observational studies performed in children with SFK are controversial, especially about the need, methodology and timing of functional assessment. This may be at least in part due to the fact that different models of SFK, including congenital and acquired after unilateral nephrectomy, are often grouped together. The aim of this study was to assess the clinical, laboratory and functional features of congenital SFK caused by URA and MCDK in children, with a particular focus on the role of renal scintigraphy in estimating kidney function during childhood and adolescence. Method We retrospectively collected clinical, laboratory and instrumental records of all consecutive pediatric patients (aged 0-18 years) affected by congenital SFK caused by URA or MCDK referred to the Nephrology and Dialysis Unit of Meyer Children’s Hospital of Florence (Italy) from 1992 to 2019. Patients with unilateral kidney hypodysplasia were excluded. In particular, we reviewed data from ultrasound scanning and sequential renal scintigraphy over time. URA and MCDK were compared for clinical features, long-term course and outcome. Results A total of 155 patients with congenital SFK were included in the study and divided in two groups according to the cause of SFK (URA, n=100; MCDK, n=55). The median length of follow-up was 47 and 45 months, respectively. Male sex and ethnicity were equally distributed in the two groups. Prenatal diagnosis was more frequent in MCDK group. We did not observe either preterm birth or low birth weight in patients enrolled. Overall, the clinical features were not statistically different between the two groups. In particular, SFK associated CAKUT, including vesicoureteral reflux, occurred at a comparable frequency. Also, measurement of kidney length by ultrasound scanning, which is often considered suggestive of compensatory hypertrophy, did not differ between groups. Although renal clearance from sequential renal scintigraphy appeared not statistically different between URA and MCDK, the latter seems to reach complete functional adaptation more rapidly and earlier in the first two years of life. Conclusion The clinical course and long-term outcome of SFK has been a topic of extensive debate. Due to poor-quality of data (unclear inclusion/exclusion criteria, lack of uniformity in data collection and outcome definition), generalization of findings from observational studies to all patients with SFK could be inappropriate. Congenital SFK could represent the most unbiased group to analyze and this study provides a thorough clinical characterization of a large and strictly selected cohort. Insights from sequential renal scintigraphy suggest a different trend in reaching single kidney complete functional adaptation in URA and MCDK. These results could potentially reveal significant differences in the pathophysiologic mechanisms of reaching compensatory hypertrophy and functional adaptation by the solitary kidney in the two models. Whether confirmed in larger cohorts, these findings could provide important implications for follow-up planning, informing the need, methodology and timing for function assessment, tailoring the clinical management and understanding long-term prognosis.

Correlation between hypertrophy and risk of hypertension in congenital solitary functioning kidney.

Solitary functioning kidney (SFK) may be associated to hypertrophy, hypertension and chronic kidney disease. We evaluated blood pressure (BP) of children with congenital SFK comparing agenesis to multicystic dysplastic kidney (MCDK) and correlated BP profiles with renal dimensions of affected and contralateral kidney. We compared 40 patients with MCDK, grouped for either treatment options (A: conservative vs B: nephrectomy) or involution time (A1: before 4 years-of-age vs A2: persistence-of-MCDK), to 10 unilateral agenesis (C). Patients were evaluated with ultrasound, scintigraphy, office-ambulatory BP monitoring. Compensatory hypertrophy was demonstrated in most of the subjects, without differences between subgroups, with an increase over time (p < 0.001). A1-C showed an overall percentage of hypertrophy significantly higher than A2-B (83%-88% vs 70%-73%, respectively; p = 0.03); moreover, cumulative risk to develop hypertension in A1-C is significantly higher compared to A2-B in office and ambulatory BP monitoring (p = 0.03). Insufficient dipping in systolic and/or diastolic BP was found in 82% children, without differences between subtypes. Patients with a small/absent dysplastic kidney have an increased risk to develop hypertrophy and hypertension compared to patients with a large residual, regardless of nephrectomy. ABPM revealed absent dipping in most patients with SFK, warning further investigations in apparently not symptomatic patients.

Congenital solitary kidney size at birth could predict reduced eGFR levels later in life.

To evaluate the impact of congenital solitary functioning kidney (CSFK) length, measured early in life, on the eGFR levels during the follow-up. We retrospectively selected 162 CSFK patients undergoing, within 60 days of life, renal length (RL) measurement by ultrasound. We divided the population in: Group 1 = RL ≥ 2 standard deviation score (SDS). Group 2 = RL < 2 SDS and showing RL ≥ 2 SDS during the follow-up. Group 3 = RL < 2 SDS and showing RL < 2 SDS during the follow-up. development of eGFR below the range of normality. The median follow-up period of the overall population was 6.2 years (range 2-21.5 years). The cumulative proportion of patients free of primary outcome at 15 years of age was 96.4% in group 1, 64.6% in group 2, and 45.6% in group 3 (p = 0.03). The RL > 2 SDS within 60 days of life was a significant protective factor (hazard ratio = 0.13; 95% C.I. 0.02-0.97) against development of primary outcome. RL ≥ 2 SDS within 60 days of life could identify a population of CSFK with reduced risk of presenting reduced eGFR levels later in life.

A clinical predictive model of renal injury in children with congenital solitary functioning kidney.

Solitary functioning kidney (SFK) is an important condition in the spectrum of congenital anomalies of the kidney and urinary tract. The aim of this study was to describe the risk factors for renal injury in a cohort of patients with congenital SFK. In this retrospective cohort study, 162 patients with SFK were systematically followed up (median, 8.5years). The primary endpoint was time until the occurrence of a composite event of renal injury, which includes proteinuria, hypertension, and chronic kidney disease (CKD). A predictive model was developed using Cox proportional hazards model and evaluated by c statistics. Among 162 children with SFK included in the analysis, 132 (81.5%) presented multicystic dysplastic kidney, 20 (12.3%) renal hypodysplasia, and 10 (6.2%) unilateral renal agenesis. Of 162 patients included in the analysis, 10 (6.2%) presented persistent proteinuria, 11 (6.8%) had hypertension, 9 (5.6%) developed CKD stage ≥ 3, and 18 (11%) developed the composite outcome. After adjustment by the Cox model, three variables remained as independent predictors of the composite event: creatinine (HR, 3.93; P < 0.001), recurrent urinary tract infection (UTI) (HR, 5.05; P = 0.002), and contralateral renal length at admission (HR, 0.974; P = 0.002). The probability of the composite event at 10years of age was estimated as 3%, 11%, and 56% for patients assigned to the low-risk, medium-risk, and high-risk groups, respectively (P < 0.001). Our findings have shown an overall low risk of renal injury for most of infants with congenital SFK. Nevertheless, our prediction model enabled the identification of a subgroup of patients with an increased risk of renal injury over time.

Renal functional reserve in children with a solitary functioning kidney and chronic kidney disease

O bjective – To examine renal functional reserve (RFR) and blood pressure (BP) in children with a solitary functioning kidney (SFK) and stage 1-3 chronic kidney disease (CKD). M ethod – RFR was measured in 48 children with SFK and in 10 healthy children, as the difference between unstimulated and stimulated clearance of endogenous creatinine by a meat-free oral protein load (OPL). Cimetidine was given 48 h prior to the measurement when the study subjects were on a diet free of meat, fish and poultry. Serum cystatin C and urinary protein (UPRT)/urinary creatinine (UCr) were examined before and 2 hours after OPL. BP was determined by office and by 24-h ambulatory BP monitoring (ABPM). R esults – The majority of the patients (79.6%) had congenital SFK, while the remaining had acquired SFK due to unilateral nephrectomy. Sixteen patients had CKD1, 19 patients had CKD2 and 13 had CKD3. The patients and controls did not differ in terms of age, gender, body size, office and 24-h blood pressure readings and basal GFR. Kidney size was greater and serum cystatin C was higher in patients than in controls. Increased proteinuria and arterial hypertension were found in 24.3% and 18.9% of the patients, respectively. Nocturnal hypertension was more common than that during the daytime. After OPL, GFR significantly increased, more in controls than in patients. Among the patients, the RFR was the highest in the CKD3 group. Conclusion – OPL induced an increase in GFR above its basal value. This response was higher in healthy children than in those with SFK. The positive relationship between RFR and CKD stage and the highest RFR in CKD3 patients suggests well preserved renal functional reserve in patients with moderate renal failure. ABPM is necessary for BP evaluation in children with SFK.

Outcomes of prenatally diagnosed solitary functioning kidney during early life.

To evaluate outcomes of congenital solitary functioning kidney (SFK) in early childhood. A retrospective study of 32 children diagnosed in utero with SFK owing to unilateral renal agenesis or multicystic dysplastic kidney and followed for 1 to 11.5 years. SFK length was in the compensatory hypertrophy range in 45% of fetal sonographic evaluations from mid-pregnancy, and in 85% on postnatal follow-up. Glomerular filtration rate was below normal range in 44.4%, 12.5% and 0% at <1 year, age 1 to 3 years and thereafter, respectively. Hyperfiltration was detected in 18.5% and 82.6% at <1 year and >3 years, respectively. Hypertension was documented in 35% at age 1 to 3 years but in none at an older age. Proteinuria was absent in all children. Congenital SFK is apparently associated with little or no renal damage in infancy or childhood. Compensatory enlargement of the functioning kidney begins in utero and might serve as a prognostic indicator for normal renal function after birth.

Outcomes of a Cohort of Prenatally Diagnosed and Early Enrolled Patients with Congenital Solitary Functioning Kidney.

We evaluated the clinical course of patients prenatally diagnosed and enrolled early with congenital solitary functioning kidney, and identified the risk factors for renal injury. We retrospectively evaluated 322 patients with congenital solitary functioning kidney according to the inclusion criteria of 1)prenatal diagnosis of solitary kidney; 2) first evaluation at 1 to 3 months of life with confirmation of congenital solitary functioning kidney, and evaluation of possible associated congenital anomalies of the kidney and urinary tract by abdominal ultrasound, renal scintigraphy and cystography; and 3) absence of any condition potentially affecting renal function in the neonatal period as well as absence of renal injury at enrollment (1 to 3 months of life) confirmed by a normal estimated glomerular filtration rate, lack of proteinuria and hypertension. Followup of 306 patients was evaluated. Median followup was 7.2 years (range 1 to 23) and 1 or more signs of renal injury were found in 12 of 306 patients (3.9%). Considering the entire population the cumulative proportion of patients free from renal injury at 17 years old was 93.7%, vs 81.3% and 95.9% for subjects with and those without congenital anomalies of the kidney and urinary tract of congenital solitary functioning kidney (p <0.001), respectively. Of congenital anomalies of the kidney and urinary tract, congenital solitary functioning kidney resulted in significant risk factors for renal injury (HR 8.75, 95% CI 2.77-27.65). In an evaluation of a large cohort of patients enrolled early with congenital solitary functioning kidney with a prenatal diagnosis, excluding those with neonatal onset of renal damage, the prevalence of renal damage was 3.9%. Among congenital anomalies of the kidney and urinary tract, congenital solitary functioning kidney represented the major risk factor.