Effect of gender and lean body mass on kidney size in healthy 10-year-old children

Correlation of renal length with anthropometric and demographic data in healthy children: A prospective cross sectional study

Background

Renal size is an important parameter in the assessment of a child with renal disease. Renal size can be estimated by measuring renal length, renal volume, and cortical volume or thickness. Renal length depends on different factors, which include size, body mass index and gender. Ultrasonography is useful, non-invasive and easily available method for reliably performing the measurement of kidney length. This study was conducted to find out correlation between renal length and age and anthropometric variables in healthy children. This prospective cross sectional study was carried out with the following objectives: (a) To determine the anthropometric variable that correlated best with renal length in healthy children. (b) To develop a nomogram for renal length in healthy children.

Methods

Five hundred healthy children were included in this study. Sonographic assessment of renal length was performed using real time mechanical sector scanner with 5 MHz and 8 MHz frequency. The renal length was correlated with somatic parameters like age, weight, height, body surface area and body mass index. Regression equations were derived for each pair of dependent and independent variables.

Results

We performed the measurement of renal length in 500 healthy children. In our series, renal measuring parameters showed a good correlation with studied body parameters, height having the best correlation. Data from left and right kidneys are shown separately since there was small but statistically significant difference between them. Based on our study, using the height of the child, renal length may be calculated by using following equation: Left renal length (cm) = 0.052 × height (cm) + 1.042, Right renal length (cm) = 0.052 × height (cm) + 0.867.

Conclusions

This study provides values of renal length (mean ± 2SD) in normal Indian children and its correlation with body parameters. Renal length may be easily calculated by derived linear regression equation. Nomograms of renal length with respect to age and height have been formulated. Renal Length was found to correlate best with height of the child.

Association of linear growth velocities between 0 and 6 years with kidney function and size at 10 years: A birth cohort study in Ethiopia

BACKGROUND

Risk of noncommunicable diseases accrues from fetal life, with early childhood growth having an important role in adult disease risk. There is a need to understand how early-life growth relates to kidney function and size.

OBJECTIVES

This study aimed to assess the association of linear growth velocities among children between 0 and 6 y with kidney function and size among children aged 10 y.

METHODS

The Ethiopian Anthropometric and Body Composition birth cohort recruited infants born at term to mothers living in Jimma with a birth weight of ≥1500 g and without congenital malformations. Participants were followed up with 13 measurements between birth and 6 y of age. The latest follow-up was at ages 7-12 y with measurement of serum cystatin C as a marker of kidney function and ultrasound assessment of kidney dimensions. Kidney volume was computed using an ellipsoid formula. Linear-spline multilevel modeling was used to compute linear growth velocities between 0 and 6 y. Multiple linear regression modeling was used to examine the associations of linear growth velocities in selected age periods with cystatin C and kidney size.

RESULTS

Data were captured from 355 children, at a mean age of 10 (range 7-12) y. The linear growth velocity was high between 0 and 3 mo and then decreased with age. There was no evidence of an association of growth velocity ≤24 mo with cystatin C at 10 y. Between 24 and 48 and 48 and 76 mo, serum cystatin C was higher by 2.3% [95% confidence interval (CI): 0.6, 4.2] and 2.1% (95% CI: 0.3, 4.0) for 1 SD higher linear growth velocity, respectively. We found a positive association between linear growth velocities at all intervals between 0 and 6 y and kidney volume.

CONCLUSIONS

Greater linear growth between 0 and 6 y of development was positively associated with kidney size, and greater growth velocity after 2 y was associated with higher serum cystatin C concentrations.

Kidney length normative values in children aged 0-19 years - a multicenter study

BACKGROUND

Currently used pediatric kidney length normative values are based on small single-center studies, do not include kidney function assessment, and focus mostly on newborns and infants. We aimed to develop ultrasound-based kidney length normative values derived from a large group of European Caucasian children with normal kidney function.

METHODS

Out of 1,782 children aged 0-19 years, 1,758 individuals with no present or past kidney disease and normal estimated glomerular filtration rate had sonographic assessment of kidney length. The results were correlated with anthropometric parameters and estimated glomerular filtration rate. Kidney length was correlated with age, height, body surface area, and body mass index. Height-related kidney length curves and table were generated using the LMS method. Multivariate regression analysis with collinearity checks was used to evaluate kidney length predictors.

RESULTS

There was no significant difference in kidney size in relation to height between boys and girls. We found significant (p < 0.001), but clinically unimportant (Cohen's D effect size = 0.04 and 0.06) differences between prone vs. supine position (mean paired difference = 0.64 mm, 95% CI = 0.49-0.77) and left vs. right kidneys (mean paired difference = 1.03 mm, 95% CI = 0.83-1.21), respectively. For kidney length prediction, the highest coefficient correlation was observed with height (adjusted R² = 0.87, p < 0.0001).

CONCLUSIONS

We present height-related LMS-percentile curves and tables of kidney length which may serve as normative values for kidney length in children from birth to 19 years of age. The most significant predictor of kidney length was statural height.

Are body surface area based estimates of liver volume applicable to children with overweight or obesity? An in vivo validation study

The liver is the primary organ responsible for clearing most drugs from the body and thus determines systemic drug concentrations over time. Drug clearance by the liver appears to be directly related to organ size. In children, organ size changes as children age and grow. Liver volume has been correlated with body surface area (BSA) in healthy children and adults and has been estimated by functions of BSA. However, these relationships were derived from "typical" populations and it is unknown whether they extend to estimations of liver volumes for population "outliers," such as children with overweight or obesity, who today represent one-third of the pediatric population. Using computerized tomography or magnetic resonance imaging, this study measured liver volumes in 99 children (2-21 years) with normal weight, overweight, or obesity and compared organ measurements with estimates calculated using an established liver volume equation. A previously developed equation relating BSA to liver volume adequately estimates liver volumes in children, regardless of weight status.

Dump the "dimorphism": Comprehensive synthesis of human brain studies reveals few male-female differences beyond size

With the explosion of neuroimaging, differences between male and female brains have been exhaustively analyzed. Here we synthesize three decades of human MRI and postmortem data, emphasizing meta-analyses and other large studies, which collectively reveal few reliable sex/gender differences and a history of unreplicated claims. Males' brains are larger than females' from birth, stabilizing around 11 % in adults. This size difference accounts for other reproducible findings: higher white/gray matter ratio, intra- versus interhemispheric connectivity, and regional cortical and subcortical volumes in males. But when structural and lateralization differences are present independent of size, sex/gender explains only about 1% of total variance. Connectome differences and multivariate sex/gender prediction are largely based on brain size, and perform poorly across diverse populations. Task-based fMRI has especially failed to find reproducible activation differences between men and women in verbal, spatial or emotion processing due to high rates of false discovery. Overall, male/female brain differences appear trivial and population-specific. The human brain is not "sexually dimorphic."

Normal sonographic renal length measurements in an Australian pediatric population

BACKGROUND

Reference charts depicting normal growth are important for the sonographic assessment of the pediatric kidney. Limited charts are available for clinical use in an Australian population.

OBJECTIVE

To retrospectively collate sonographic renal length measurements in a cohort of low-risk Australian children aged newborn to 16 years to produce a reference table and comparison with other published charts.

MATERIALS AND METHODS

We identified consecutive pediatric patients who were at low risk for renal disease and had renal lengths measured. After exclusions, we included 941 renal lengths (male 490, female 451). We used linear regression to estimate the relationship of renal length with age, gender and side. We calculated percentile values of renal length according to age categories.

RESULTS

No statistically significant differences in mean renal length were observed between males and females, or for left and right kidneys. We tabulated reference data and provide them in a reference chart (1-, 2.5-, 5-, 10-, 50-, 90-, 97.5- and 99-percentiles).

CONCLUSION

We calculated new reference ranges for pediatric renal length using a larger cohort than previously published, from a population with diverse ethnicity.

Ultrasonographic length of morphologically-normal kidneys in children presented to a premier tertiary healthcare setting of Sri Lanka

Background

Accurate prediction of reference ranges of renal lengths facilitates clinical decision making. Currently a single renal-length-reference chart is used for both kidneys, which is solely based on the age of the child without adjusting for anthropometrics.

Objective of the study is to assess the length of morphologically-normal kidneys ultrasonically and to build models to predict the renal lengths of children presenting at the Radiology Department of Lady Ridgeway Hospital for Children.

Methods

A descriptive cross sectional study was done among 424 children with 233 males and 191 females at the study setting. Study population included children undergoing abdominal ultrasound scans for indications not related to renal disease. Children with a family history of renal diseases or with morphologically-abnormal kidneys were excluded. Bipolar-lengths of kidneys, gender and anthropometrics were documented. Having tested for assumptions, Wilcoxon-signed rank test, Mann-Whitney U test and multiple linear regression were used.

Results

The mean (SD) bipor-length of right and left kidneys were 6.83 (1.43) and 7.05 (1.36) respectively (p < 0.001). Age, height and weight were significantly correlated with the renal lengths (p < 0.05). Until 16 months, there was a significant difference between the renal lengths between males and females (P < 0.05). Yet the association with gender was not significant from 17 months and in overall. Until 16 months, the best linear-regression equation (p < 0.001) for the left kidney was; 3.827 +  0.019(length in centimeters) +  0.141(weight in kilograms) - 0.023(age in months) - 0.347(for male sex). For the right kidney, it was; 3.888 + 0.020(length or height) + 0.121(weight) - 0.037(age) - 0.372 (for male sex). The respective R squares were 59.2 and 53.5% with VIF (Variance-Inflation-Factor) ranging from 1.06 to 2.08. From 17 months, best equation for left kidney (p < 0.001) was; 5.651+ 0.022(age) + 0.01(BMI). For right kidney it was; 5.336 + 0.022(age) + 0.012(BMI). The R squares were 62.5 and 66.1% with VIF being 1.

Conclusions

The established models explain more variability for children above 17 months. Both renal lengths are affected significant by the body’s’ anthropometric parameters. For each kidney, separate normograms of renal lengths which are local-context-specific must be prepared. Further research must be promoted.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1377-z) contains supplementary material, which is available to authorized users.

Sonographic measurements for kidney length in normal Saudi children: correlation with other body parameters

BACKGROUND

Ultrasonography provides a quick assessment of visceral organ dimensions without any risk of radiation. Since many diseases can affect the kidney size, having a reliable reference for kidney length in children is valuable for clinical assessment.

OBJECTIVE

Establish normal growth curves for renal length in relation to sex, age, body weight, height, body mass index and body surface area of healthy children in Saudi Arabia.

DESIGN

Retrospective review of ultrasonography images.

SETTING

Tertiary referral hospital.

PATIENTS AND METHODS

We included all normal ultrasonography exams of renal length from full-term neonates to children ≤14 years old performed between 2003 and 2018. Data was collected retrospectively from the electronic archive and patient records.

MAIN OUTCOME MEASURES

Relationship between the longitudinal length of both kidneys and age, height, weight, body mass index and body surface area.

SAMPLE SIZE

950 patients.

RESULTS

The left kidneys were longer than the right kidneys ( P<.001). Height had the most significant correlation with kidney length (R²=0.829, P<.001 for right kidney; R²=0.831, P<.001 for left kidney). There was a consistent difference in kidney length by sex. Both kidneys were longer in males than females ( P=.031, right kidney:, P=.015, left kidney). In terms of renal growth by age, our data showed a statistically significant difference before and after 24 months of age. There was no significant difference between populations from Saudi Arabia, Hong Kong ( P=.485) and Australia ( P=.99), but the difference between Saudi and American children was significant ( P<.001). However, we did not have the data from those studies for direct comparison. The correlation plots of renal length versus age for all four countries were similar.

CONCLUSION

The tables and correlation plots generated from this study should be useful to radiology departments in assessing conditions in children ≤14 years of age that lead to changes in renal size.

LIMITATIONS

Retrospective, and there were differences in ultrasonographic techniques for patient positioning and cursor placement that can affect the reproducibility of measurements of renal length.

CONFLICT OF INTEREST

None.

Are normative sonographic values of kidney size in children valid and reliable? A systematic review of the methodological quality of ultrasound studies using the Anatomical Quality Assessment (AQUA) tool

BACKGROUND AND OBJECTIVES

A plethora of research is available on ultrasonographic kidney size standards. We performed a systematic review of methodological quality of ultrasound studies aimed at developing normative renal parameters in healthy children, by evaluating the risk of bias (ROB) using the 'Anatomical Quality Assessment (AQUA)' tool.

METHODS

We searched Medline, Scopus, CINAHL, and Google Scholar on June 04 2018, and observational studies measuring kidney size by ultrasonography in healthy children (0-18 years) were included. The ROB of each study was evaluated in five domains using a 20 item coding scheme based on AQUA tool framework.

RESULTS

Fifty-four studies were included. Domain 1 (subject characteristics) had a high ROB in 63% of studies due to the unclear description of age, sex, and ethnicity. The performance in Domain 2 (study design) was the best with 85% of studies having a prospective design. Methodological characterization (Domain 3) was poor across the studies (< 10% compliance), with suboptimal performance in the description of patient positioning, operator experience, and assessment of intra/inter-observer reliability. About three-fourth of the studies had a low ROB in Domain 4 (descriptive anatomy). Domain 5 (reporting of results) had a high ROB in approximately half of the studies, the majority reporting results in the form of central tendency measures.

CONCLUSIONS

Significant deficiencies and heterogeneity were observed in the methodological quality of USG studies performed to-date for measurement of kidney size in children. We hereby provide a framework for the conducting such studies in future. PROSPERO (CRD42017071601).

Ultrasonographic renal volume in Chinese children: Results of 1683 cases

BACKGROUND

At present, little information has been made available in the evaluation of renal volume in pediatric groups of different ages.

PURPOSE

The purposes of the study are to evaluate the relationship between anthropometric measurements and renal volume measured with three-dimensional ultrasonography in Chinese children who have normal kidneys, and to attempt to develop reliable reference values of renal volume to estimate the renal sizes.

METHODS

A total of 1572 Chinese Han children suffering from stomachache, cryptorchidism and neurogenic enuresis with no history of renal disease or pathological abnormalities that might affect measurements, aged 1month to 12years (mean, 5.64years) were examined bilateral kidneys by ultrasonography. The measurements of renal volume were determined using QLAB software in IU22 units (Philips Medical Systems, Holland). Anthropometric indices including sex, age, height and weight were collected for reviewed analysis.

RESULTS

A total of 1683 children were included, and renal volume of 1572 cases (93.4%) was accepted. There was no significant difference between renal volumes of male and female separately in left and right kidneys (P=0.844 and P=0.621, respectively), whereas there was a significant difference between mean left and right renal volumes (P=0.000). Age, height and weight were all significant correlations with renal volume (R(2), 0.885 and 0.913 for the left and right kidneys, respectively, both P=0.000), and age was the strongest correlation with renal volume (r, 0.472 and 0.399 for the left and right kidneys, respectively) among the anthropometric indices. We drew regression equations to estimate renal volume as follows: left renal volume (cm(3))=0.441×age+0.156×height+0.398×weight+6.677 and right renal volume (cm(3))=0.256×age+0.195×height+0.632×weight+1.788, and developed reference values of renal volume separately for the left and right kidneys in different age groups.

CONCLUSIONS

Regression equations have been developed, which define the renal volume from three-dimensional ultrasonography and may assist pediatricians in monitoring renal growth and detecting of unsuspected bilateral increases or decreases in renal size.

Infant Breastfeeding and Kidney Function in School-Aged Children

BACKGROUND

Early life factors may influence kidney growth and function throughout the life course. We examined the associations of breastfeeding duration and exclusivity and age at introduction of solid foods with kidney outcomes at school age.

STUDY DESIGN

Prospective cohort study from fetal life onward.

SETTING & PARTICIPANTS

5,043 children in the Netherlands.

PREDICTORS

Infant feeding was assessed prospectively using questionnaires.

OUTCOMES & MEASUREMENTS

In children at a median age of 6.0 years, we measured kidney volume with ultrasound, estimated glomerular filtration rate (eGFR) from serum creatinine level, and microalbuminuria from urinary albumin and creatinine levels.

RESULTS

92% of all children were ever breastfed, of whom 27% were breastfed for more than 6 months and 21% were breastfed exclusively for at least 4 months. Compared with ever-breastfed children, never-breastfed children had smaller combined kidney volumes (-2.69 [95% CI, -4.83 to -0.56] cm(3)) and lower eGFRs (-2.42 [95% CI, -4.56 to -0.28] mL/min/1.73 m(2)) at school age. Among breastfed children, shorter duration of breastfeeding was associated with smaller combined kidney volume and lower microalbuminuria risk (P<0.05). Compared to exclusive breastfeeding for 4 months, nonexclusive breastfeeding in the first 4 months was associated with smaller combined kidney volume and lower eGFR (both P<0.05). Associations with eGFR were explained largely by kidney volume. Age at introduction of solid foods was not associated with any kidney outcome.

LIMITATIONS

Observational study, so causality cannot be established. Follow-up measurements were available for 76% of children.

CONCLUSIONS

These results suggest that breastfeeding is associated with subclinical changes in kidney outcomes in childhood. Further studies are needed to explore whether early life nutrition also affects the risk of kidney disease in adulthood.

Protein intake in infancy and kidney size and function at the age of 6 years: The Generation R Study

BACKGROUND

High protein intake has been linked to kidney growth and function. Whether protein intake is related to kidney outcomes in healthy children is unclear.

METHODS

We examined the associations between protein intake in infancy and kidney outcomes at age 6 years in 2968 children participating in a population-based cohort study. Protein intake at 1 year was assessed using a food-frequency questionnaire and was adjusted for energy intake. At age 6 years we measured the kidney volume and urinary albumin/creatinine ratio (ACR) of all participating children, and we estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C levels.

RESULTS

In models adjusted for age, sex, body surface area, and sociodemographic factors, a higher protein intake was associated with a lower ACR and a higher eGFR but was not consistently associated with kidney volume. However, after further adjustment for additional dietary and lifestyle factors, such as sodium intake, diet quality, and television watching, higher protein intake was no longer associated with kidney function. No differences in associations were observed between animal and vegetable protein intake.

CONCLUSIONS

Our findings show that protein intake in early childhood is not independently associated with kidney size or function at the age of 6 years. Further study is needed on other early life predictors of kidney size and function in later life.

Length and volume of morphologically normal kidneys in korean children: ultrasound measurement and estimation using body size

OBJECTIVE

To evaluate the relationship between anthropometric measurements and renal length and volume measured with ultrasound in Korean children who have morphologically normal kidneys, and to create simple equations to estimate the renal sizes using the anthropometric measurements.

MATERIALS AND METHODS

We examined 794 Korean children under 18 years of age including a total of 394 boys and 400 girls without renal problems. The maximum renal length (L) (cm), orthogonal anterior-posterior diameter (D) (cm) and width (W) (cm) of each kidney were measured on ultrasound. Kidney volume was calculated as 0.523 × L × D × W (cm(3)). Anthropometric indices including height (cm), weight (kg) and body mass index (m(2)/kg) were collected through a medical record review. We used linear regression analysis to create simple equations to estimate the renal length and the volume with those anthropometric indices that were mostly correlated with the US-measured renal sizes.

RESULTS

Renal length showed the strongest significant correlation with patient height (R(2), 0.874 and 0.875 for the right and left kidneys, respectively, p < 0.001). Renal volume showed the strongest significant correlation with patient weight (R(2), 0.842 and 0.854 for the right and left kidneys, respectively, p < 0.001). The following equations were developed to describe these relationships with an estimated 95% range of renal length and volume (R(2), 0.826-0.884, p < 0.001): renal length = 2.383 + 0.045 × Height (± 1.135) and = 2.374 + 0.047 × Height (± 1.173) for the right and left kidneys, respectively; and renal volume = 7.941 + 1.246 × Weight (± 15.920) and = 7.303 + 1.532 × Weight (± 18.704) for the right and left kidneys, respectively.

CONCLUSION

Scatter plots between height and renal length and between weight and renal volume have been established from Korean children and simple equations between them have been developed for use in clinical practice.

Simple, age-based formula for predicting renal length in children

OBJECTIVE

To determine a simple, age based formula for predicting ideal renal length in children. Renal size is a valuable marker in the evaluation of children with urological disorders. Although many authors have described complex nomograms and multivariate formulas for determining renal size, we propose a simple and accurate formula.

MATERIAL AND METHODS

All renal ultrasound (US) studies performed over a 9-year period in patients <18 years of age were retrospectively evaluated, excluding patients with a history of urinary tract disease or with abnormal renal US findings.

RESULTS

Ultrasounds were performed in 778 children <18 years who met inclusion criteria. Sixty-one percent of the patient population was ≥1 year of age at the time of the US. Forty-four percent of the children were male. In children 1 year of age or older, the formula was length (cm) = age (years) × 0.3 + 6, R(2) = .81. In infants younger than 1 year, renal length was poorly estimated by a simple age-based formula.

CONCLUSION

Our proposed formula can be used to predict renal length in children older than 1 year.

Determinants and functional significance of renal parenchymal volume in adults

BACKGROUND AND OBJECTIVES

The significance of renal parenchymal volume and the factors that influence it are poorly understood.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Renal parenchymal volume (RPV) was measured on contrast-enhanced CT scans after exclusion of sinus fat and vessels in 224 healthy subjects evaluated as kidney donors and in a separate cohort of 22 severely obese individuals before and after 6 months of weight loss. GFR was measured by iohexol clearance in 76 of the transplant donors. RPV was correlated with age, GFR, and various anthropometric parameters.

RESULTS

In potential transplant donors, RPV correlated with body surface area (BSA; r = 0.68) and was 7% larger in men but did not vary with age or race. Gender and body size were independent determinants of RPV. RPV correlated well with GFR (r = 0.62) and accounted for almost all of the variability in a model of GFR that included age, race, gender, and body surface area. GFR correlated more strongly with RPV than with creatinine-based equations. The same relationship between RPV and BSA was observed in obesity, and RPV decreased with weight loss.

CONCLUSIONS

In healthy adults younger than 65 years, renal parenchymal volume is governed by body size and gender but not age or race and is strongly correlated with GFR. This indicates that renal parenchymal volume varies to meet metabolic demand and is closely linked to renal function.

Increased protein intake augments kidney volume and function in healthy infants

Protein intake has been directly associated with kidney growth and function in animal and human observational studies. Protein supply can vary widely during the first months of life, thus promoting different kidney growth patterns and possibly affecting kidney and cardiovascular health in the long term. To explore this further, we examined 601 healthy 6-month-old formula-fed infants who had been randomly assigned within the first 8 weeks of life to a 1-year program of formula with low-protein (LP) or high-protein (HP) contents and compared them with 204 breastfed (BF) infants. At 6 months, infants receiving the HP formula had significantly higher kidney volume (determined by ultrasonography) and ratios of kidney volume to body length and kidney volume to body surface area than did infants receiving the LP formula. BF infants did not differ from those receiving the LP formula in any of these parameters. Infants receiving the HP formula had significantly higher serum urea and urea to creatinine ratios than did LP formula and BF infants. Hence, in this European multicenter clinical trial, we found that a higher protein content of the infant formula increases kidney size at 6 months of life, whereas a lower protein supply achieves kidney size indistinguishable from that of healthy BF infants. The potential long-term effects of a higher early protein intake on long-term kidney function needs to be determined.

Pediatric urolithiasis--does body mass index influence stone presentation and treatment?

PURPOSE

Pediatric obesity is a major public health concern in the United States. We investigated the association of body mass index with presentation and outcome in children with urolithiasis.

MATERIALS AND METHODS

We identified all patients 2 to 18 years old at our institution with a radiographically confirmed first renal or ureteral stone between January 2003 and June 2008. Data abstracted included demographics, stone characteristics, treatment and metabolic evaluation. Patients were stratified into 3 body mass index categories, including lower (10th percentile or less for age), normal (10th to 85th percentile) and upper (85th percentile or greater) percentile body weight.

RESULTS

Of the children 62 boys (55.4%) and 50 girls (44.6%) were evaluable. Mean age at diagnosis was 11.8 years. Body mass index stratification showed lower percentile body weight in 11 patients (9.8%), normal percentile body weight in 55 (49.1%) and upper percentile body weight in 46 (41.1%). Mean stone diameter was 5.0 mm. Of the stones 31 (27.7%) were in the kidney or ureteropelvic junction and 81 (72.3%) were in the ureter. Surgery was done in 87 patients (78.9%) and stone clearance was accomplished by 1 (69.0%) or 2 (31.0%) procedures in all. Lower percentile body weight patients presented earlier than normal and upper percentile body weight patients (9.0 vs 12.2 and 12.0 years, respectively, p = 0.04). Neither stone size nor the number of procedures required for stone clearance differed significantly by body mass index.

CONCLUSIONS

Upper percentile body weight was not associated with earlier stone development, larger stones or the need for multiple surgical procedures. In lower percentile body weight patients symptomatic renal stones developed significantly earlier than in normal or upper percentile body weight patients. Stone size and the surgical intervention rate were similar regardless of body mass index. Further research may identify potential factors predisposing children with lower percentile body weight to early stone development.

Kidney growth curves in healthy children from the third trimester of pregnancy until the age of two years. The Generation R Study

Information about growth of kidney structures in early life is limited. In a population-based prospective cohort study, from foetal life onwards, we constructed reference curves for kidney growth from the third trimester of pregnancy until early childhood, using data from 1,158 healthy children. Kidney size, defined as length, width, depth and volume, was measured in the third trimester of pregnancy and at the postnatal ages of 6 months and 24 months. Analyses were based on more than 2,500 kidney measurements. In the third trimester of pregnancy and at 6 months of age all kidney measurements were larger in boys than in girls. At 24 months of age, these gender differences were only significant for left kidney structures and right kidney length. Both groups showed trends towards smaller left kidney measurements than right kidney measurements at all ages. Gender-specific reference curves based on post-conceptional and postnatal ages were constructed for left and right kidney length, width, depth and volume. We concluded that kidney size is influenced by age and gender. Left kidney size tended to be smaller than right kidney size, except for kidney length. The reference curves can be used for assessing kidney structures by ultrasound in foetal life and early childhood.

The effect of malnutrition on kidney size in children

Malnutrition is a widespread disorder in children, and ultrasonography is the method of choice to estimate kidney dimensions. Previously, kidney sizes had been studied in healthy newborns and in pediatric patients; however, kidney sizes were not investigated sufficiently in malnourished children. The study group consisted of 74 children with energy malnutrition (marasmus), and the control group consisted of 47 healthy children. Kidney sizes were mesaured by the same radiologist using ultrasonography. The mean age of the marasmic group was 29.6 +/- 14.0 months. Malnourished children had significantly lower kidney length and renal volume but higher relative kidney volume (cm3/body weight) compared with controls (P < 0.05). The mean length and volume of left kidney were higher than those of right kidney in both marasmic and control groups (P < 0.05). The strongest positive correlations were found between body height and kidney length, depth and volume in marasmic group. Regression analysis revealed that height and age of marasmic children had a significant effect on kidney volume; however, only body height had an effect on kidney length. In conclusion, malnourished children had smaller kidney sizes, and body height was the main determinant of their kidney length and volume. The potential long-term detrimental consequences of poor renal growth in malnutrition need to be investigated.

Impaired kidney growth in low-birth-weight children: Distinct effects of maturity and weight for gestational age

BACKGROUND

Chronic kidney disease (CKD) alters the regulation of calcium and phosphate homeostasis, leading to secondary hyperparathyroidism, metabolic bone disease, soft tissue calcifications, and other metabolic derangements that have a significant impact on morbidity and mortality. The parathyroid gland is the central organ responsible for regulating these adaptive responses. Suppression of parathyroid hormone (PTH) secretion, hypertrophy, and hyperplasia are a major goal of treatment of CKD.

METHODS

Current literature was reviewed and combined with the author's experience to address a number of issues regarding the optimal treatment of secondary hyperparathyroidism in hemodialysis patients.

RESULTS

The calcium sensing receptor (CASR) is the most important factor regulating parathyroid gland function, and allosteric modulators of CASR, called calcimimetics, provide a novel drug therapy to suppress PTH secretion. The current use of active vitamin D analogues to suppress PTH is often limited by hypercalcemia and hyperphosphatemia. Clinical trials of cinacalcet HCl, the first calcimimetic to be approved for treatment of secondary hyperparathyroidism in CKD, have demonstrated suppression of circulating PTH levels without increments in the calcium-phosphorus (Ca x P) product, making it easier to achieve the stringent management guidelines proposed for subjects with CKD by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI).

CONCLUSION

The management of disordered calcium and phosphate homeostasis in CKD patients is evolving based on our knowledge of the major importance of the calcium sensing receptor (CASR) in controlling parathyroid gland function and the potent actions of calcimimetics to target CASR. The purpose of this presentation is to provide an overview of the role of the CASR in regulation of parathyroid gland function, to examine the mechanisms whereby calcimimetics target the CASR, and to review the clinical trials that support the use of cinacalcet HCl for the treatment of secondary hyperparathyroidism in stage 5 chronic kidney disease (CKD).

AGE AND LEAN BODY WEIGHT RELATED GROWTH CURVES OF KIDNEYS USING REAL-TIME 3-DIMENSIONAL ULTRASOUND IN PEDIATRIC UROLOGY

PURPOSE

Kidney volume and growth are important parameters for evaluating and monitoring several diseases in pediatric urology. Studies have shown the significant relationship of kidney volume and function. Until now normal values of kidney size and growth have been based on 2-dimensional measurements combined with arithmetic formulas for the ellipsoid. Real-time 3-dimensional (RT3D) ultrasound is a new imaging modality. Moreover, corresponding software allows RT3D imaging within a short time exposure. We created nomograms of kidney volumes for routine diagnostics that could serve as a standard for pediatric renal growth assessment, decreasing the need for invasive tests.

MATERIALS AND METHODS

RT3D volumetry of a total of 620 kidneys in 310 children with a homogeneous age distribution (range newborn to 10 years) and without any evidence of renal impairment was performed using a Voluson 730 (Kretztechnik, Ultrasound, Zipf, Austria) system. Polynomial regression analysis was applied for the prediction and estimation of growth variables of kidney volumes as a function of gender, age, body mass index or lean body weight.

RESULTS

Stepwise multiple regression analysis incorporating the different independent variables indicated with significant correlation that age and lean body weight were the strongest predictors of kidney volumes in children.

CONCLUSIONS

This study shows that RT3D ultrasound is particularly qualified for evaluating kidney volume in pediatric urology. RT3D volumetry is suitable for monitoring renal growth, reflecting kidney function. Furthermore, this methodology is feasible in screening programs assessing congenital urogenital diseases.

Kidney growth in 717 healthy children aged 0-18 months: a longitudinal cohort study

Kidney size is an important parameter in the evaluation of children with renal disease. However, reference materials for kidney size in healthy children have been limited beyond the neonatal period. We performed a longitudinal cohort study of 717 healthy children born at term with normal birth weight. Kidney size and shape were determined by ultrasonography and related to gender, age, and body size (weight, length, body surface area, skinfold thickness) at 0, 3, and 18 months of age. Gender-differentiated reference charts were established. Boys had significantly larger kidney volumes than girls ( P<0.001) and larger relative volumes (kidney volume/weight) at 0 and 3 months ( P<0.001), but not at 18 months of age. The best single predictor of gender-differentiated kidney volume was weight. Relative kidney volume changed with increasing age and height in a two-phase pattern: an initial decrease until a height of 65-70 cm was reached followed by a stable level. In conclusion, kidney size was significantly influenced by gender, age, and body composition. Relative kidney volume decreased with increasing age and height in a two-phase pattern. These characteristic changes in kidney volume indicated that infant kidney growth might be influenced by sex steroids and growth hormone in addition to body composition.