Childhood Estimates of Glomerular Filtration Rate Based on Creatinine and Cystatin C: Importance of Body Composition

Mother-child correlation of kidney function: data from the Yamanashi Adjunct Study of Japan Environment and Children's Study (JECS)

BACKGROUND

Individual variation in kidney function can be affected by both congenital and acquired factors, and kidney function in children is possibly correlated with that in their mothers. However, the mother-child correlation in kidney function remains directly unconfirmed.

METHODS

We conducted a cross-sectional study of 655 healthy pairs of 7- or 8-year-old children and their mothers as an adjunct study of a nationwide epidemiological study (Japan Environment and Children's Study).

RESULTS

Both serum creatinine level (all children, r = 0.324, p < 0.001; girls, r = 0.365, p < 0.001; boys, r = 0.278, p < 0.001) and estimated glomerular filtration rate (eGFR) (r = 0.274, p < 0.001; r = 0.352, p < 0.001; r = 0.195, p < 0.001, respectively) in children were weakly associated with their maternal values. In the single linear regression analyses, maternal values of serum creatinine and eGFR were significantly associated with the children's values. Moreover, several body composition values in children, such as weight-SDS, fat (%), and predicted muscle weight, were also significantly associated with kidney function values in children. In the multiple linear regression analysis for serum creatinine levels in children, in which weight-SDS and predicted muscle weight in children were selected as adjustment factors, maternal serum creatinine level showed a significant positive association (B = 0.214, p < 0.001 in the adjusted model). Moreover, in the multiple linear regression analysis for eGFR value in children, in which fat (%) and predicted muscle weight in children were selected as adjustment factors, maternal eGFR values showed a significant positive association (B = 0.319, p < 0.001).

CONCLUSIONS

We directly confirmed mother-child correlations in both serum creatinine levels and eGFR values, particularly in girls. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

Childhood Obesity: Insight into Kidney Involvement

This review examines the impact of childhood obesity on the kidney from an epidemiological, pathogenetic, clinical, and pathological perspective, with the aim of providing pediatricians and nephrologists with the most current data on this topic. The prevalence of childhood obesity and chronic kidney disease (CKD) is steadily increasing worldwide, reaching epidemic proportions. While the impact of obesity in children with CKD is less pronounced than in adults, recent studies suggest a similar trend in the child population. This is likely due to the significant association between obesity and the two leading causes of end-stage renal disease (ESRD): diabetes mellitus (DM) and hypertension. Obesity is a complex, systemic disease that reflects interactions between environmental and genetic factors. A key mechanism of kidney damage is related to metabolic syndrome and insulin resistance. Therefore, we can speculate about an adipose tissue-kidney axis in which neurohormonal and immunological mechanisms exacerbate complications resulting from obesity. Adipose tissue, now recognized as an endocrine organ, secretes cytokines called adipokines that may induce adaptive or maladaptive responses in renal cells, leading to kidney fibrosis. The impact of obesity on kidney transplant-related outcomes for both donors and recipients is also significant, making stringent preventive measures critical in the pre- and post-transplant phases. The challenge lies in identifying renal involvement as early as possible, as it is often completely asymptomatic and not detectable through common markers of kidney function. Ongoing research into innovative technologies, such as proteomics and metabolomics, aims to identify new biomarkers and is constantly evolving. Many aspects of pediatric disease progression in the population of children with obesity still require clarification. However, the latest scientific evidence in the field of nephrology offers glimpses into various new perspectives, such as genetic factors, comorbidities, and novel biomarkers. Investigating these aspects early could potentially improve the prognosis of these young patients through new diagnostic and therapeutic strategies. Hence, the aim of this review is to provide a comprehensive exploration of the pathogenetic mechanisms and prevalent pathological patterns of kidney damage observed in children with obesity.

Cystatin C-Based eGFR Changes during Gender-Affirming Hormone Therapy in Transgender Individuals

BACKGROUND

Men with CKD tend to experience a faster eGFR decline than women, potentially because of sex hormones. Limited research exists regarding the effect of gender-affirming hormone therapy (GAHT) on kidney function. Furthermore, monitoring kidney function during GAHT is challenging because serum creatinine is confounded by body composition. To investigate the relationship between sex hormones and kidney function, we studied the changes of serum creatinine and serum cystatin C, a filtration marker less affected by sex, during 1 year of GAHT.

METHODS

As part of the European Network for the Investigation of Gender Incongruence study, we measured serum creatinine and serum cystatin C in 260 transgender women and 285 transgender men before and 12 months after initiating GAHT. Transgender women received estradiol plus cyproterone acetate, while transgender men received testosterone. Cystatin C-based eGFR was calculated using the full-age-spectrum equation.

RESULTS

In transgender women, cystatin C decreased by 0.069 mg/L (95% confidence interval [CI], 0.049 to 0.089), corresponding with a 7 ml/min per 1.73 m 2 increase in eGFR. In transgender men, cystatin C increased by 0.052 mg/L (95% CI, 0.031 to 0.072), corresponding with a 6 ml/min per 1.73 m 2 decrease in eGFR. Creatinine concentrations decreased (-0.065 mg/dl; 95% CI, -0.076 to -0.054) in transgender women and increased (+0.131 mg/dl; 95% CI, 0.119 to 0.142) in transgender men. Changes in creatinine-based eGFR varied substantially depending on the sex used in the equation.

CONCLUSIONS

In this cohort of transgender individuals, cystatin C-based eGFR increased with estradiol and antiandrogen therapy and decreased with testosterone therapy.

Predictors of survival following liver transplantation for pediatric hepatoblastoma and hepatocellular carcinoma: Experience from the Society of Pediatric Liver Transplantation (SPLIT)

Management of unresectable pediatric hepatoblastoma (HB) and hepatocellular carcinoma (HCC) remains challenging. The Society of Pediatric Liver Transplantation (SPLIT) database was used to study survival predictors in pediatric liver transplantation (LT) for HB and HCC. Event-free survival (EFS), associated risk factors, and postoperative complications were studied in children requiring LT for HB/HCC at 16 SPLIT centers. Three-year EFS was 81% for HB (n = 157) and 62% for HCC (n = 18) transplants. Of HB transplants, 6.9% were PRETEXT II and 15.3% were POST-TEXT I/II. Tumor extent did not impact survival (p = NS). Salvage (n = 13) and primary HB transplants had similar 3-year EFS (62% versus 78%, p = NS). Among HCC transplants, 3-year EFS was poorer in older patients (38% in ≥8-year-olds vs 86% <8-year-olds) and those with larger tumors (48% for those beyond versus 83% within Milan criteria, p = NS). Risk of infection (HR 1.5, 95% CI 1.1-2.2, p = .02) and renal injury (HR 2.4, 95% CI 1.7-3.3, p < .001) were higher in malignant versus nonmalignant LT. Survival is favorable for pediatric HB and HCC LT, including outcomes after salvage transplant. Unexpected numbers of LTs occurred in PRE/POST-TEXT I/II tumors. Judicious patient selection is critical to distinguish tumors that are potentially resectable; simultaneously, we must advocate for patients with unresectable malignancies to receive organs.

Assessment of Cystatin-C level in Newly Diagnosed Iraqi Children with Nephritic Syndrome

BACKGROUND: Nephritic syndrome (NS) is a common kidney disease in children that causes protein leakage from the blood into the urine due to glomerular injury. AIM: The aim of this research was to determine the level of Cystatin-C (CysC) and other biochemical parameters in newly diagnosed NS children in Iraq. PATIENTS AND METHODS: Ninety Iraqi children divided into: 50 children with newly diagnosed NS (28 boys and 22 girls) aged between (4 and 16) years, and 40 healthy control children (20 boys and 20 girls) aged between (5 and 16) years, who were attending Al-Yarmouk Teaching Hospital, Baghdad. RESULTS: There was a significant increase in blood urea, serum total cholesterol (S.TC), and serum low density lipoprotein (S.LDL) and a significant decreased of serum creatinine (S. creatinine), protein/creatinine ratio, serum total bilirubin, serum albumin, and serum high density lipoprotein, while a highly significant increased (p < 0.001) of CysC levels in children with newly diagnosed NS when compared with control group. A significant positive correlation between CysC level versus systolic blood pressure, body mass index, diastolic blood pressure, S.TC, S. LDL cholesterol (S.LDL-C), S. Total Bilirubin, S. Albumin, S. Total protein, and B. urea, while a significant negative correlation was found between CysC level versus serum low density lipoprotein cholesterol and estimated glomerular filtration rate in children with newly diagnosed NS. CONCLUSION: It may come to the conclusion that CysC can be the best predictor of overall efficacy than creatinine and in the diagnosis of any damage to the kidney in children with NS.

Cystatin C relates to metabolism in healthy, pubertal adolescents

INTRODUCTION

The cystatin C (CysC) serum level is a marker of glomerular filtration rate and depends on age, gender, and pubertal stage. We hypothesize that CysC might overall reflect energy homeostasis and be regulated by components of the endocrine system and metabolites in pubertal adolescents.

METHODS

Serum CysC levels and further possible effector parameters in 5355 fasting, morning venous blood samples from 2035 healthy participants of the LIFE Child cohort study (age 8 to 18 years) were analyzed. Recruitment started in 2011, with probands followed up once a year. Linear univariate and stepwise multivariate regression analyses were performed.

RESULTS

Annual growth rate, serum levels of thyroid hormones, parathyroid hormone, insulin-like growth factor 1, hemoglobin A1c (HbA1c), uric acid, and alkaline phosphatase show relevant and significant associations with CysC serum concentrations (p <0.001). Furthermore, male probands' CysC correlated with the body mass index and testosterone among other sexual hormones. Multivariate analyses revealed that uric acid and HbA1c are associated variables of CysC independent from gender (p <0.001). In males, alkaline phosphatase (p <0.001) is additionally significantly associated with CysC. Thyroid hormones show significant correlations only in multivariate analyses in females (p <0.001).

CONCLUSIONS

The described associations strongly suggest an impact of children's metabolism on CysC serum levels. These alterations need to be considered in kidney diagnostics using CysC in adolescents. Additionally, further studies are needed on CysC in children.

Cystatin and Glomerular Filtration Rate in Obese Versus Non-obese Adolescents

Background: Obesity is well known as an independent risk factor for chronic kidney disease. Thus meticulous assessment of renal function is more essential in obese individuals. Glomerular filtration rate (GFR) is commonly estimated based on serum creatinine (Cr).  However, using Cr as marker of kidney function has some limitations and Cystatin C has been reported as an alternative marker. Aim of work: This study was designed to assess renal function using both GFR and cystatin in obese adolescents. Methods: This case-control study enrolled ninety Egyptian adolescents aged between 10 and 18 years old who were divided equally into two groups according to body mass index (obese and non-obese).  Each participant was subjected to full medical history taking, anthropometric measures, and Laboratory investigation including CBC, serum Cr, estimated GFR and cystatin C. Results:  Serum Cr level was significantly higher in obese adolescents compared to non-obese mean value (0.94) and (0.79) resepectively. Also, eGFR based on Cr was significantly lower in obese group compared to controls (73.1) and ( (85.30)respectively. Cystatin C showed non-significant higher levels in obese group versus controls with mean value (2.28) and (1.85)respectively. Cystatin C at Cut-off value of 1.525 and 95% CI showed sensitivity of 47.2% and specificity of 63.9% for evaluation of kidney affection in obese children and adolescences. Conclusion: GFR is affected in obese adolescence with elevation of serum creatinine and unexpected non significant elevation of cystatin C in obese adolescence when compared by control group. Keywords: Cystatin, Creatinine, Pediatric obesity, GFR, renal function.

Distribution of creatinine and estimated glomerular filtration rate in healthy schoolchildren: The Health Oriented Pedagogical Project (HOPP)

Glomerular filtration rate (GFR) measured by urinary clearance of inulin is considered the gold standard for assessment of kidney function in both adults and children. Because the procedure is cumbersome, GFR is estimated (eGFR) using algorithms based on the observed relationship between measured GFR (mGFR) and more accessible biomarkers such as creatinine and cystatin C. In children, most of the data on this relationship is retrieved from patients with reduced kidney function. Nonetheless, eGFR equations are widely in use in healthy children to evaluate kidney status and diagnose kidney disease. The aim of the present study was to compare the distribution of eGFR using two established pediatric eGFR equations incorporating age, height and serum creatinine (Schwartz-Lyon and Full Age Spectrum-height) and two recently published equations restricted to age and serum creatinine (Lund-Malmö Revised 18 and European Kidney Function Consortium equation) in 1200 healthy schoolchildren age 6-12 years. In addition, we present 2.5^th, median and 97.5^th percentiles for serum creatinine stratified by age and gender. Depending on the equation used, mean eGFR ranged from 101.6 to 115.4 mL/min/1.73 m². The lower 2.5^th percentile ranged from 83.3 to 89.0 mL/min/1.73 m² and the fraction of children with eGFR < 90 mL/min/1.73 m² ranged from 2.9% to 9.8%. In conclusion, expected values of eGFR in healthy children are significantly dependent on the equation used. When decision limits for diagnosis or classification are applied to eGFR results, the related equation should be clearly stated.

Indices calculated by serum creatinine and cystatin C as predictors of liver damage, muscle strength and sarcopenia in liver disease

Serum creatinine (Cr)-based glomerular filtration rate (CrGFR) is overestimated in liver disease. The present study evaluated whether the difference in CrGFR and cystatin C (CysC) GFR (dGFR) is significant in liver disease. The Cr-to-CysC ratio and sarcopenia index (SI) have been reported to correlate with muscle volume. An estimated total body muscle mass with Cr, CysC and calculated body muscle mass (CBMM) has also been reported to correlate with muscle mass. The applicability of dGFR, SI and CBMM for liver disease were evaluated. A total of 313 patients with liver damage were evaluated for Child-Pugh score, albumin-bilirubin (ALBI) score, model for end-stage liver disease, fibrosis-4, Cr, CysC, Cr-based estimated GFR (CreGFR), CysCGFR and grip strength. Of the 313 patients, 199 were evaluated using cross-sectional computed tomography (CT) of the third lumbar vertebra to determine the skeletal muscle (SM) mass. dGFR, CBMM and SI were compared to liver damage, muscle strength and muscle mass. In the 313 patients, dGFR was correlated with age, ALBI and grip strength; CBMM was correlated with body mass index (BMI) and grip strength; and SI was correlated with BMI and grip strength. In patients evaluated with CT, the correlation coefficients for CBMM and SI with SM were 0.804 and 0.293, respectively. Thus, CBMM and SI were associated with sarcopenia. The relationship between dGFR and ALBI does not differ with different grades of CrGFR-based chronic kidney disease (CKD). dGFR is a marker of liver damage and muscle strength regardless of CKD. CBMM and SI are markers for sarcopenia in liver disease.

Can childhood obesity influence later chronic kidney disease?

Childhood overweight and obesity affects more and more children. Whilst associations of childhood overweight with later outcomes such as hypertension, diabetes and cardiovascular disease have been well documented, less is known about the association of childhood overweight and obesity with kidney disease. We review the existing evidence for the association of childhood obesity with markers of childhood and adult kidney disease. Whilst there is some evidence for an association, studies have not been able to distinguish between childhood being a sensitive time to develop later kidney problems, or whether observed associations of childhood obesity with poor outcomes are driven by greater lifelong exposure to obesity.

Body composition and arterial stiffness in pediatric patients with chronic kidney disease

BACKGROUND

This study investigated the impact of body composition in the arterial stiffness of children with chronic kidney disease (CKD).

METHODS

Fat mass (FM), fat tissue index (FTI), fat-free mass (FFM), fat-free tissue index (FFTI), and FFTI/FTI were measured in 26 patients and 25 healthy controls by bio-impedance analysis. Data on patient's body mass index (BMI) for height-age, serum albumin, glomerular filtration rate (GFR), blood pressure status, and pulse wave velocity (PWV) were collected in patients.

RESULTS

Patients presented lower levels of FM and FFM compared to healthy controls (p = 0.04 and p = 0.055 respectively). In patient group, BMI height-age z-score was positively correlated to FTI (r² = 0.574, p < 0.001) and FFTI (r² = 0.338, p = 0.001) and negatively correlated to FFTI/FTI (r² = 0.263, p = 0.007). Serum albumin was positively correlated only with FFM among body composition data (r² = 0.169, p = 0.037). PWV z-score was positively correlated to FFTI (r² = 0.421, p = 0.006) and inversely correlated to FFTI/FTI ≥ 2.5 (r² = 0.317, p = 0.003). Patients with FFTI/FTI ≥ 2.5 presented lower levels of PWV regardless the need for antihypertensive treatment. Serum albumin ≥ 3.8 mg/dl and FFTI/FTI ≥ 2.5 were independently associated with a lower risk for high PWV, after adjustment for age, sex, and GFR (OR 0.009, 95% CI 0.000-0.729 and OR 0.039, 95% CI 0.002-0.680). All underweight [2 (7.7%)] and overweight [4 (15.4%)] patients presented high PWV. Among normal weight patients, FFTI/FTI ratio ≥ 2.5 was significantly associated with lower PWV z-score (p = 0.013).

CONCLUSIONS

Both underweight and overweight are associated with arterial stiffness. Targeting FFTI/FTI ≥ 2.5 could be protective against cardiovascular disease in normal weight children.

Evaluation of Renal Function in Obese Children and Adolescents Using Serum Cystatin C Levels, Estimated Glomerular Filtration Rate Formulae and Proteinuria: Which is most Useful?

OBJECTIVE

There is a growing interest in the relationship between obesity and renal damage. The effect of obesity on renal function in children and adolescents has not been adequately investigated. In addition, there is no complete consensus on the reliability of various renal function parameters. The primary goal of this study was to evaluate renal function in obese children and adolescents using glomerular filtration rate (GFR), cystatin C, and creatinine (Cr)-derived formulas. We also compared classical GFR measurement methods with methods based on bioimpedance analysis-derived body cell mass (BCM).

METHODS

We enrolled 108 obese and 46 healthy subjects aged 6-18 years. Serum cystatin C, serum Cr, 24-hour proteinuria, Cr clearance, and GFR were evaluated in both groups. Estimated GFR was measured with Cr-based, cystatin C-based, combined (cystatin C and Cr) and BCM-based formulae. Both actual and fat-free mass body surface areas (BSA) were used when required. Metabolic parameters (blood glucose, insulin, and lipids) were analyzed in the obese subjects. International Diabetes Federation criteria were used to identify metabolic syndrome (MetS).

RESULTS

We did not detect statistically significant differences between the obese and control groups for mean Cr (p=0.658) and mean cystatin C (p=0.126). Mean cystatin C levels of MetS patients were significantly higher than those of non-MetS obese participants (p<0.001). Cr-based GFR measurements, BCM-based measurements and a combined Cr and cystatin C measurement showed a statistically significant increase in the GFR of obese subjects compared to controls (p=0.002 and p<0.001). This increase was negatively correlated with duration of obesity. Estimations based on actual or fat-free mass BSA did not differ either. Only the Filler equation showed a statistically significant decrease in eGFR in MetS patients. There were no statistically significant differences between the obese and control groups for proteinuria (p=0.994) and fat-free mass proteinuria (p=0.476).

CONCLUSION

We conclude that cystatin C could be used as an earlier biomarker than Cr in the detection of impaired renal function in obese children, especially those with MetS. Cr-based formulae reveal hyperfiltration as the first change in renal function. Decreasing eGFR seen in MetS patients with cystatin C-based formulae, but not Cr-based formulae, may represent the early stages of renal damage. Using fat-free mass or BCM for eGFR formulae in obese children seems to provide no additional information.

Cystatin C serum levels in healthy children are related to age, gender, and pubertal stage

BACKGROUND

This study aims to establish age- and gender-specific cystatin C (CysC) reference values for healthy infants, children, and adolescents and to relate them to pubertal stage, height, weight, and body mass index (BMI).

METHODS

Serum CysC and creatinine levels of 6217 fasting, morning venous blood samples from 2803 healthy participants of the LIFE Child study (age 3 months to 18 years) were analyzed by an immunoassay. Recruitment started in 2011; 1636 participants provided at least one follow-up measurement. Percentiles for CysC were calculated. Age- and gender-related effects of height, weight, BMI, and puberty status were assessed through linear regression models.

RESULTS

Over the first 2 years of life, median CysC levels decrease depending on height (ß = - 0.010 mg/l/cm, p < 0.001) and weight (ß = - 0.033 mg/l/kg, p < 0.001) from 1.06 to 0.88 mg/l for males and from 1.04 to 0.87 mg/l for females. Following the second year of age, the levels remain stable for eight years. From 11 to 14 years of age, there is an increase of median CysC levels in males to 0.98 mg/l and a decrease in females to 0.86 mg/l. The change is associated with puberty (ß = 0.105 mg/l/Tanner stage, p < 0.001 in males and ß = - 0.093 mg/l/Tanner stage, p < 0.01 in females) and in males with height (ß = 0.003 mg/l/cm, p < 0.001).

CONCLUSIONS

CysC levels depend on age, gender, and height, especially during infancy and puberty. We recommend the use of age- and gender-specific reference values for CysC serum levels for estimating kidney function in clinical practice.

Social Determinants of Health Are Associated with Markers of Renal Injury in Adolescents with Type 1 Diabetes

OBJECTIVE

To examine the relationship between the social determinants of health and markers of early renal injury in adolescent patients with type 1 diabetes (T1D).

STUDY DESIGN

Renal outcomes included estimated glomerular filtration rate (eGFR) and albumin-creatinine excretion ratio (ACR). Differences in urinary and serum inflammatory markers also were assessed in relation to social determinants of health. Regression analysis was used to evaluate the association between the Ontario Marginalization Index (ON-Marg) as a measure of the social determinants of health, patient characteristics, ACR, eGFR, and renal filtration status (hyperfiltration vs normofiltration).

RESULTS

Participants with T1D (n = 199) with a mean age of 14.4 ± 1.7 years and diabetes duration of 7.2 ± 3.1 years were studied. Mean eGFR was 122.0 ± 19.4 mL/min/1.73 m². Increasing marginalization was positively associated with eGFR (P < .0001) but not with ACR (P = .605). Greater marginalization was associated with greater median levels of urinary interleukin (IL)-2, IL-12 (p40), macrophage-derived chemokine, monocyte chemoattractant protein-3, and tumor necrosis factor-β and serum IL-2. ON-Marg was significantly associated with eGFR after we controlled for age, sex, body mass index z score, ethnicity, serum glucose, and hemoglobin A1c in linear regression. A similar association between hyperfiltration and ON-Marg score was observed in multivariable logistic regression.

CONCLUSION

Increasing marginalization is significantly associated with both eGFR and hyperfiltration in adolescents with T1D and is associated with significant changes in urinary inflammatory biomarkers. These findings highlight a potentially important interaction between social and biological determinants of health in adolescents with T1D.