Evaluation of kidney size in children: a pilot study of renal length as a surrogate of organ growth

Reference indices for evaluating kidney dimensions in children using anthropometric measurements

Background

Kidney pathologies often result in change in renal size. Knowledge of normal kidney sizes is important for screening, diagnosis, prognosis and follow-up management of paediatric renal diseases.

Objectives

The aim of this study was to establish the age-, height- and weight-matched kidney dimensions in apparently healthy Nigerian children.

Method

A descriptive, cross-sectional study of right and left kidney parameters (length, width, thickness and volume) of 1315 school-aged Nigerian children was conducted over 8 months. Ages ranged from 5 to 17 years. Parameters were obtained using a General Electric (GE) LOGIC 400CL ultrasound machine. Kidney dimensions were correlated with age, sex and anthropometric measurements.

Results

Normative values for all the kidney parameters for each age, height and weight groups and also gender were established for the study population. The left kidneys were noted to be longer and thicker, and of more volume than the right kidneys. The right kidneys were seen to be wider (p < 0.01). Length of the left kidneys in females was noted to be more than those of the males in the age- and weight-matched categories (p < 0.05). The width of both kidneys was higher in the males in all the categories (p < 0.05). Males showed higher values of thickness and volume in the height category. All the renal parameters significantly correlated with body size indicators, except for body mass index.

Conclusion

This study has established gender-, age-, weight- and height-specific range of values of the kidney parameters of apparently healthy children together with regression models.

The relationship between body mass index and renal length in obese children

BACKGROUND

Obesity in the pediatric population is a severe public health problem and is associated with various comorbidities. Renal length is an important clinical parameter for the diagnosis and follow-up of renal diseases. The aim of this study was to determine the relationship between renal length (measured ultrasonographically) and body mass index (BMI) in obese children, and to develop nomograms for renal length according to BMI.

METHODS

Renal ultrasound was performed in 368 children without renal disease. Each child's age, gender, weight, height, and BMI (kg/m²) were recorded. The children were divided into three groups according to BMI percentiles: obese group: BMI ≥ 95th percentile; overweight group: BMI 85th-94th percentile; normal weight group: BMI 5th-84th percentile.

RESULTS

Weight, height, BMI, and right and left renal length differed significantly between the three groups (p = 0.001). There were significant correlations between renal length with age, weight, height, and BMI. Measurement of renal length was independently associated with BMI, age, and height. BMI was used to create renal length nomograms for obese children, based on multiple regression analysis (R² = 0.32 and p = 0.0001). Mean renal length was highest in the obese group (96.9 ± 13.4 mm) and lowest in the normal weight group (88.3 ± 12.9 mm).

CONCLUSIONS

Ultrasonographic measurement of the renal length according to BMI in children can be a useful method in evaluating these children. Smaller-than-normal kidneys can easily remain undiagnosed in obese and overweight children and this nomogram offers an additional method to evaluate the renal size in obese children.

Measurement and Estimation of Renal Size by Computed Tomography in Korean Children

Adequate organ growth is an important aspect of growth evaluation in children. Renal size is an important indicator of adequate renal growth; computed tomography (CT) can closely estimate actual kidney size. However, insufficient data are available on normal renal size as measured by CT. This study aimed to evaluate the relationships of anthropometric indices with renal length and volume measured by CT in Korean pediatric patients. Renal length and volume were measured using CT images in 272 pediatric patients (age < 18 years) without renal disease. Data for anthropometric indices-including height, weight, and body surface area (BSA)-were obtained using medical records. Using the equation for an ellipsoid, renal volume was calculated in cubic centimeters. Height showed greatest correlation with renal length on stepwise multiple linear regression analysis; BSA showed the strongest significant correlation with renal volume. The mean renal size for each age group and height group was determined; it showed a tendency to increase with age and height. This is the first Korean study to report the relationship between body indices and renal size measured by CT. These results can serve as normative standards for assessing adequate renal growth.

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.

The Association between Weight for Gestational Age and Kidney Volume: A Study in Newborns in India

OBJECTIVE

The association of low birth weight (LBW) with adult onset diseases like hypertension is suggested to be partially mediated by a low number of nephrons at birth. Studies have established a relation between LBW and renal volume as the latter is a surrogate marker of total nephron number. Most such studies have considered birth weight or gestational age as separate independent predictors, without taking into consideration the baby's weight with respect to its gestational age. This study aims to investigate the influence of weight for gestational age on kidney volume in newborns.

METHODS

Consecutive newborns delivered in the department of neonatology in a tertiary care medical college and hospital, were included in a cross-sectional study. The subjects were classified as appropriate for gestational age (AGA) and small for gestational age (SGA) as per Lubchenco's charts of weight for gestational age (WGA). Bilateral kidney dimensions were measured by a single observer and combined kidney volumes were calculated and compared between the groups. Findings : Four hundred and seventeen newborns (SGA 159; AGA 258) were included. The mean combined kidney volume (CKV) was significantly lower among SGA newborns (13.85±4.02 cm(3)) compared to that of AGA (16.88±4.53 cm(3)) (P<.001). Univariable and multivariable analyses were done for assessing the effect of demographic, anthropometric and maternal parameters on CKV. WGA, crown heel length, gestational age and postnatal age (hours of life) were independent predictors of mean CKV. An SGA newborn was expected to have a mean CKV 1.57 cm less (95% CI -2.49 cm to -0.65 cm) than that of its AGA counterpart.

CONCLUSION

Considering the future implications of being SGA and having low kidney volumes at birth, it is essential to have an objective depiction of the relationship between these two vital parameters. This study from the Indian subcontinent brings forth such an association.

Kidney size estimation in Korean children with Technesium-99m dimercaptosuccinic acid scintigraphy

PURPOSE

Renal size is an important indicator to determine adequate organ growth in children. The aim of this study was to estimate renal size with Technesium-99m dimercaptosuccinic acid (DMSA) scan and propose a simple formula for predicting renal length in normal Korean children.

METHODS

This study included 346 children (148 boys and 198 girls; age range, 1 month to 17 years) in whom renal length was measured using the DMSA scan. Patients with anatomical renal abnormalities or acute pyelonephritis were excluded. Children were divided into two groups: 214 children (61.8%) were less than a year old (group 1) and 132 (38.2%) were ≥1 year (group 2).

RESULTS

Renal length was larger on the left side than the right side, and there was no significant gender-related difference in renal length. We propose the following formula for renal length based on the analysis of the 346 children in our study: the formula was as follows: 4.682×age (month)(0.137), R(2) =0.780. In group 1, the formula was renal length (cm)=0.127×age (month)+5.144, R(2) =0.354, and in group 2, the formula was 0.334×age (year)+6.477, R(2) =0.829.

CONCLUSION

It is difficult to establish simple formulae in infants (R(2) =0.354). Therefore, further studies including relevant variables are needed for this age group. We proposed formulae to estimate renal length in Korean children over 1 year of age by using the DMSA scan.

Diagnostic value of electrocardiography compared with echocardiography in measuring left ventricular mass index in major thalassemia patients over 10 years of age

BACKGROUND

Patients suffering from major beta thalassemia need frequent blood transfusions and, if not treated well, would be at risk of heart dysfunction. This study was performed to determine the diagnostic value of electrocardiography versus echocardiography in measuring the left ventricular mass index in these patients.

METHODS

Between July 2010 and June 2011, 82 asymptomatic patients over 10 years of age with major thalassemia (42 men with a mean age of 17.65 ± 3.39 years and 40 women with a mean age of 16.9 ± 3.38 years) were enrolled in this study. For all the patients, standard electrocardiography (to measure R in aVL and S in V3 and calculate left ventricular mass index by electrocardiography) and echocardiography (to measure interventricular septum diameter in diastole, left ventricular posterior wall diameter in diastole, and left ventricular diameter in diastole in order to calculate left ventricular mass index by echocardiography) were performed, at least one week after transfusion. The calculated left ventricular mass indices were thereafter compared between the two methods (electrocardiography and echocardiography).

RESULTS

Sensitivity, specificity, positive predictive value, and negative predictive value in the two techniques in determining the left ventricular mass index were 67%, 25%, 89%, and 7% in the females, 65%, 33%, 92%, and 6% in the males, and 67%, 14%, 89%, and 3% in the total population, respectively. Furthermore, this study demonstrated that the average left ventricular mass index by echocardiography and electrocardiography was 104.86 ± 21.65 gr/m2 and 91.69 ± 12.03 gr/m2, respectively. Echocardiography was much more accurate than electrocardiography in determining the left ventricular mass index (p value = 0.0001).

CONCLUSION

The findings of this study demonstrated that echocardiography was more accurate and more reliable than electrocardiography in determining the left ventricular mass index in major thalassemia patients.