The evaluation of kidney function estimation during lifestyle intervention in children with overweight and obesity.

BACKGROUND: Children with overweight and obesity are at risk for developing chronic kidney disease (CKD). During lifestyle adjustment, the first step in the treatment of childhood obesity, body proportions are likely to change. The aim of this study was to examine how lifestyle intervention affects creatinine-based kidney function estimation in children with overweight and obesity. METHODS: This longitudinal lifestyle intervention study included 614 children with overweight and obesity (mean age 12.17 ± 3.28 years, 53.6% female, mean BMI z-score 3.32 ± 0.75). Loss to follow-up was present: 305, 146, 70, 26, and 10 children were included after 1, 2, 3, 4, and 5 (about yearly) follow-up visits, respectively. Serum creatinine (SCr) was rescaled using Q-age and Q-height polynomials. RESULTS: At baseline, 95-97% of the children had a SCr/Q-height and SCr/Q-age in the normal reference range [0.67-1.33]. SCr/Q significantly increased each (about yearly) follow-up visit, and linear mixed regression analyses demonstrated slopes between 0.01 and 0.04 (corresponding with eGFR FAS reduction of 1.1-4.1 mL/min/1.73 m2) per visit. BMI z-score reduced in both sexes and this reduction was significantly higher in males. No correlation between change in rescaled SCr and BMI z-score reduction could be demonstrated. CONCLUSIONS: Rescaled serum creatinine (SCr/Q) slightly increases during multidiscipline lifestyle intervention in this cohort of children with overweight and obesity. This effect seems to be independent from change in BMI z-score. Whether this minor decrease in estimated kidney function has clinical consequences in the long term remains to be seen in trials with a longer follow-up period. CLINICAL TRIAL REGISTRATION: ClinicalTrial.gov; Registration Number: NCT02091544.

Relation between obesity-related comorbidities and kidney function estimation in children.

BACKGROUND: The current childhood obesity pandemic is likely to result in an increased risk of chronic kidney disease (CKD) later in life. Correlations between obesity-related comorbidities and kidney function can be found, but it is unclear to what extent this is caused by bias due to different mathematical forms of the estimated glomerular filtration rate (eGFR) equations. The present study aimed to analyze correlations between obesity-related comorbidities and different eGFR equations and to investigate whether rescaled serum creatinine (SCr/Q) for sex and age or height might be an alternative biomarker for kidney function estimation. METHODS: This cross-sectional cohort study included 600 children with overweight and obesity. Mean age was 12.20 ± 3.28 years, 53.5% were female, and mean BMI z-score was 3.31 ± 0.75. All children underwent a comprehensive assessment that included anthropometrical and blood pressure measurements, laboratory examination, air displacement plethysmography, and polysomnography. Qage and Qheight polynomials were used to rescale SCr and multiple creatinine-based eGFR equations were compared. RESULTS: SCr/Q and almost all GFR estimations significantly correlated with a waist-to-hip ratio, fat mass, homeostasis model assessment for insulin resistance, and triacylglyceride, HDL cholesterol, alanine transaminase, and serum uric acid concentrations. Multiple correlations, however, were not confirmed by all equations, which suggests dependency on the mathematical form of the different eGFR equations. CONCLUSIONS: Correlations between obesity-related comorbidities and creatinine-based eGFR are present in children with overweight and obesity, but depend to a large extent on the eGFR equation of choice. SCr/Q might be an alternative biomarker for assessing correlations between obesity-related comorbidities and kidney function in children with overweight and obesity. A higher resolution version of the Graphical abstract is available as Supplementary information.

Creatinine-based GFR-estimating equations in children with overweight and obesity.

BACKGROUND: With the increasing prevalence of childhood obesity and related development of chronic kidney disease (CKD), there is a critical need to understand how best to assess kidney function in children with obesity. Since serum creatinine (SCr) is recommended as marker of first choice for GFR estimation, we evaluated and compared creatinine-based GFR equations in children with overweight and obesity. METHODS: Six hundred children with overweight and obesity (53.5% female; mean age 12.20 ± 3.28 years; mean BMI z-score 3.31 ± 0.75) were included from the Centre for Overweight Adolescent and Children's Healthcare (COACH). RESULTS: Serum creatinine (SCr), normalized using Q-age polynomials obtained from reference values, results in median and mean SCr/Q value close to "1" for all age groups, and 96.5% of the children have a SCr/Q within the reference band [0.67-1.33], corresponding to the 2.5th and 97.5th percentile. eGFR CKiD (bedside Schwartz equation) and Schwartz-Lyon decreased with age, whereas eGFR EKFC and modified CKD-EPI40 showed no age-dependency, but the distribution of eGFR values was not symmetrical. eGFR CKiD under 25 (CKiDU25) demonstrated no age-dependency but major sex differences were observed. eGFR FAS age, FAS height, and adjusted-creatinine revised Lund-Malmö (LMR18) showed a relatively symmetrical distribution and no age-dependency. CONCLUSIONS: Serum creatinine (SCr) values of children with overweight and obesity are mostly within the reference range for children. Normalization of SCr using reference Q-age polynomials works very well in this cohort. After evaluation of the different equations, we suggest that FAS age, FAS height, and LMR18 are the preferred creatinine-based GFR-estimating equations in children with overweight and obesity. CLINICALTRIAL: gov; Registration Number: NCT02091544. A higher resolution version of the Graphical abstract is available as Supplementary information.

Case Report: Uterine Anomalies in Girls With a Congenital Solitary Functioning Kidney.

Unilateral renal agenesis and multicystic dysplastic kidney, resulting in a contralateral solitary functioning kidney (SFK), are part of the broad spectrum of congenital anomalies of the kidney and urinary tract (CAKUT). In girls with SFK, screening for asymptomatic Müllerian anomalies of uterus and vagina is not yet routinely performed, and therefore often overlooked until clinical complications in the menstrual cycle or fertility process occur. In this case series, we report on four teenagers with congenital SFK presenting with menstrual problems due to a Müllerian anomaly. Routine peri-menarchal screening for Müllerian anomalies in girls with SFK may provide timely counseling, surgical treatment and prevention of associated complications such as endometriosis, infertility and miscarriages.