Ultrasonographic renal parenchymal volume related to kidney function and renal parenchymal area in children with recurrent urinary tract infections and asymptomatic bacteriuria

Sonographic temporary nephromegaly in children during their first febrile urinary tract infection is a significant prognostic factor for recurrent infection

There are currently no available data on the relationship between sonographic temporary nephromegaly in children during their first febrile urinary tract infection (fUTI) and recurrent fUTI. For this analysis, a multicenter retrospective cohort study of 343 children who underwent renal ultrasound during their first fUTI was conducted between 2013 and 2020. Sonographic temporary nephromegaly was defined as increased renal length during the initial fUTI, followed by normal renal length after antibiotic treatment. Compared with children without sonographic temporary nephromegaly (n = 307), the duration of fever and intravenous antibiotics was significantly longer, and C-reactive protein, creatinine, and the proportion of children who had recurrent fUTI were significantly higher, in those with sonographic temporary nephromegaly (n = 36). In an additional analysis of 100 patients who received voiding cystourethrography, a logistic regression model confirmed that the odds of vesicoureteral reflux (VUR) were significantly higher in children with temporary nephromegaly or those who experienced fUTI recurrence. In nine out of 16 children with VUR who had temporary nephromegaly, the reason for receiving voiding cystourethrography was recurrent fUTI. Our results suggest that sonographic temporary nephromegaly during an initial fUTI is predictive for recurrence and VUR, and that in children with temporary nephromegaly, VUR may be detectable before fUTI recurrence.

The Application Value of the Renal Region of Interest Corrected by Computed Tomography in Single-Kidney Glomerular Filtration Rate for the Evaluation of Patients With Moderate or Severe Hydronephrosis

Objective: This study aimed to investigate the application value of the renal region of interest (ROI) corrected by computed tomography (CT) in single-kidney glomerular filtration rate (GFR) in patients with hydronephrosis. Methods: A total of 46 patients with hydronephrosis were divided into four groups based on their degree of unilateral hydronephrosis: a normal group (left kidney and right kidney) and three abnormal groups (mild, moderate, and severe hydronephrosis). GFR was measured using the two-sample method (tGFR). The single-kidney GFR of each patient was derived from differential renal function values in dynamic renal imaging multiplied by GFR. The single-kidney GFRs, including GFR from the Gates method (gGFRsingle) and CT area-corrected GFR (aGFRsingle), were compared with tGFRsingle. A paired-sample t-test and Pearson's test were used for data analysis. p < 0.05 was considered statistically significant. Results: There were no significant differences between aGFRsingle and tGFRsingle in patients in the normal, mild hydronephrosis, and moderate hydronephrosis groups (t = -0.604∼1.982, all p > 0.05), but there was a significant difference between them in the severe hydronephrosis group (t = 2.302, p < 0.05). There were no significant differences between gGFRsingle and tGFRsingle in the normal and mild hydronephrosis groups (t = 0.194∼0.962, all p > 0.05), but there was a significant difference between them in the moderate and severe hydronephrosis groups (t = 3.321, 3.494, p < 0.05). Both gGFRsingle and aGFRsingle were correlated with tGFRsingle, with aGFRsingle being more strongly correlated (r = 0.890, p < 0.001). Conclusion: In patients with moderate hydronephrosis, aGFRsingle is more strongly correlated with tGFRsingle than gGFRsingle. However, in patients with severe hydronephrosis and accompanying renal morphological changes, the aGFRsingle measured by the renal ROI area-correction method using CT has higher accuracy and better clinical application value than the conventional gGFRsingle.

What are the Optimal Renal Ultrasound Parameters for Detecting Small Kidney in Young Children?

Introduction

Recent guidelines do not recommend routine screening of vesicoureteral reflux after a first febrile urinary tract infection in children without abnormal findings on ultrasound or atypical/recurrent urinary tract infection. Currently, there are no clear ultrasonographic parameters for detecting abnormalities in renal size, especially in young children. The aim of the present study was to determine an optimal cutoff value for detecting small kidney in children without apparent congenital anomalies except vesicoureteral reflux by retrospective chart review.

Patients and Methods

Children aged ≤3 years who had undergone nuclear renal scans and ultrasound were enrolled. Small kidney was defined as split renal function of <40%. Optimal cutoff values of various ultrasonographic parameters for detecting small kidney were calculated.

Results

Of the 69 children included in the present study, small kidney was identified in 20. There was a significant difference in renal size between each kidney in patients with small kidney, whereas there was no significant difference in those without small kidney. With a ratio of estimated renal area of 74.26%, maximum area under the curve with the highest sensitivity, specificity, positive predictive value, negative predictive value, and accuracy rate were obtained. In addition, simple measurement of renal length with a cutoff of 4.97 cm showed high specificity comparable with estimated renal area.

Conclusion

Small kidney may be screened by two-dimensional measurement on ultrasonographic examination, even in young children. With the cutoff described, risk stratification or an individualized approach may be possible.

Volume and function of the operated kidney after nephron-sparing surgery for unilateral renal tumor

AIM

We sought to assess the magnitude of functional decline and the natural history of the operated kidney residual function after zero-ischemia nephron-sparing surgery (Z-NSS) in children with unilateral renal tumor (URT).

PATIENTS AND METHODS

50 children were treated for URT at our surgical unit between 1992 and 2016. Of these 12 who underwent Z-NSS were available for the current analysis. Operated kidney function was assessed by 99mTc-dimercapto-succinic acid (DMSA) renal scintigraphy. Operated kidney volume was assessed by renal ultrasonography.

RESULTS

A positive correlation between split renal function and split renal volume was found (P = 0.001). The subset of patients with ≥40% preservation of operated kidney function/volume (OKF/V) had no-time dependent changes during adolescence. The subset of patients with <40% OKF/V preservation had a catch-up growth that after puberty reached values not much different from those with ≥40% OKF/V preservation. At 5 years of follow-up, 3 of 5 patients with baseline dysfunction (eGFR between 40.8 and 89.4 ml/min/1.73 m²) presented with a global renal function within normal range. After puberty, all patients presented with global renal function within normal values (eGFR between 95 and 151 ml/min/1.73 m²).

CONCLUSIONS

In children with URT who underwent Z-NSS, the pattern of OKF/V recovery suggests that compensatory catch-up growth capacity during childhood minimizes OKF/V decline more than Z-NSS.

LEVEL OF EVIDENCE

Level I prognosis study - prospective cohort study with >80% follow-up and all patients enrolled at same time point in disease.

Renal Parenchymal Volume in Children

Forty-three children with normal urograms and with kidneys of normal size regarding length, area and parenchymal thickness were examined using a water-delay computerized ultrasonographic equipment. Renal parenchymal volumes were calculated and related to body weight. The correlation coefficient was 0.92. The renal parenchymal volume of the left kidney was significantly larger than that of the right kidney (p<0.001). For practical purposes they should, however, be assumed to be of equal size, 2.0±0.3 cm3/kg body weight.

Renal ultrasound volume in children with primary vesicoureteral reflux allows functional assessment

OBJECTIVE

Renal scintigraphy represents the current diagnostic standard to assess split kidney function. We tested the hypothesis that the relative renal volume assessed by ultrasound provides an equally reliable but less invasive tool for assessment of kidney function as compared to renal scintigraphy in patients with primary vesicoureteral reflux.

METHODS

Renal ultrasound and renal scintigraphy were performed in 85 patients (median age 4.5 years, range 0.25-7.7) and repeated in 74 patients after 2-13 months (mean 7) of the primary investigation. Renal size was measured by ultrasound, and relative renal volume was calculated for each kidney by using the formula of a prolate ellipsoid. Renal function was estimated for each side (split renal function) by scintigraphy with (99m)Tc MAG3.

RESULTS

The mean difference between relative renal volume measured by ultrasound and split renal function determined by renal scintigraphy was 2.8% (standard deviation ± 4.1%; 95% confidence interval 10.8/-5.2%). There was a statistically significant correlation between relative renal volume estimated by ultrasound and split renal function estimated by renal scintigraphy at first examination (r = 0.98; p < 0.001) and at follow-up (r = 0.91; p < 0.001).

CONCLUSION

We conclude that ultrasound measurement of relative renal volume is capable of assessing split renal function in children with primary vesicoureteral reflux and, thus, should be considered instead of the more invasive MAG3 scintigraphy.

Estimation of feline renal volume using computed tomography and ultrasound

Renal volume estimation is an important parameter for clinical evaluation of kidneys and research applications. A time efficient, repeatable, and accurate method for volume estimation is required. The purpose of this study was to describe the accuracy of ultrasound and computed tomography (CT) for estimating feline renal volume. Standardized ultrasound and CT scans were acquired for kidneys of 12 cadaver cats, in situ. Ultrasound and CT multiplanar reconstructions were used to record renal length measurements that were then used to calculate volume using the prolate ellipsoid formula for volume estimation. In addition, CT studies were reconstructed at 1 mm, 5 mm, and 1 cm, and transferred to a workstation where the renal volume was calculated using the voxel count method (hand drawn regions of interest). The reference standard kidney volume was then determined ex vivo using water displacement with the Archimedes' principle. Ultrasound measurement of renal length accounted for approximately 87% of the variability in renal volume for the study population. The prolate ellipsoid formula exhibited proportional bias and underestimated renal volume by a median of 18.9%. Computed tomography volume estimates using the voxel count method with hand-traced regions of interest provided the most accurate results, with increasing accuracy for smaller voxel sizes in grossly normal kidneys (-10.1 to 0.6%). Findings from this study supported the use of CT and the voxel count method for estimating feline renal volume in future clinical and research studies.

Sonographic measurement of diuretic-induced renal length changes: are they correlated with renal function?

OBJECTIVES

The purposes of this study were to prospectively identify diuretic-induced renal length changes and to determine whether the percentages of the renal length changes allow estimation of the differential renal function.

METHODS

Twenty-three children (14 boys and 9 girls; mean age, 7.83 years) who were undergoing technetium Tc 99m diethylenetriamine pentaacetic acid or technetium Tc 99m mercaptoacetyltriglycine diuretic renography were included in this study. Renal lengths were measured by sonography just before and 15 to 20 minutes after diuretic injection. The Spearman test was used to assess the correlation between renal length increases due to diuretic injection and the differential renal function.

RESULTS

The mean renal lengths ± SD measured before and after diuretic administration were 91.52 ± 20.87 and 95.38 ± 21.46 mm, respectively. The increase in renal length after diuretic administration was statistically significant (P < .001). There was a positive correlation between the renal length change and functional status (P = .006).

CONCLUSIONS

Renal length may change after diuretic injection according to the functional status, and the sonographic measurements of these changes may be used as an alternative to other imaging methods in estimation of renal function.

Renal hemodynamics and blood pressure control in patients with pyelonephritic renal scarring

Pyelonephritic renal scarring is a common cause of renal failure and hypertension. We studied glomerular filtration rate (GFR), renal plasma flow (RPF), filtration fraction (FF), total renal area (TRA), systolic (SBP) and diastolic (DBP) blood pressure in 22 female patients with verified renal scarring and a history of febrile urinary tract infection (UTI) and in 9 healthy age-matched women with normal urograms and no history of symptomatic UTI. The patients with renal scarring had significantly lower GFR, smaller TRA and higher SBP than the healthy controls, but not significantly different RPF or FF. A decrease in GFR and RPF was associated with higher SBP and DBP in the patients with renal scarring. RPF/TRA, representing an approximation of the perfusion of renal tissue and GFR/TRA, were similar in patients with renal scarring and healthy controls. A reduction of renal parenchyma was accompanied by a proportional decrease in GFR and RPF, resulting in unchanged FF. These findings do not support the concept of hyperfiltration as a main cause of renal insufficiency in patients with pyelonephritis renal scarring. An increase in FF and a decrease in GFR/TRA and RPF/TRA was associated with higher DBP and a decrease in GFR/TRA and RPF/TRA with an increase in the urinary albumin excretion. We conclude that renal hemodynamics play an important part in the blood pressure control of patients with renal scarring and that in these patients with various degrees of renal failure there was no evidence of hyperfiltration or hyperperfusion by remnant glomeruli.

Usefulness of renal volume measurements obtained by a 3-dimensional sonographic transducer with matrix electronic arrays

OBJECTIVE

The purpose of this study was to examine the feasibility of 3-dimensional (3D) sonography using a matrix array transducer to measure renal volume.

METHODS

One hundred consecutive patients with a normal serum creatinine level and kidney appearance on computed tomography (CT) performed within 2 months before sonography were enrolled in this study. Two hundred individual renal volumes were blindly obtained by the ellipsoid formula, the stacked ellipse method, the voxel count method using routine 2-dimensional (2D) sonographic data, 3D sonographic data using a matrix array transducer, and CT data, respectively. The voxel count method was validated as the reference standard by the water displacement method in 10 cadaveric pig kidneys (r = 0.99; P < .001). Renal volumes determined by 2D and 3D sonography were compared with volumes determined by CT.

RESULTS

Volumes determined by 2D sonography were significantly lower than those determined by CT (P < .001) but similar to those determined by 3D sonography (P = .78). The percent volume error of 3D sonography (mean +/- SD, -2.2% +/- 3.7%) was significantly lower than that of 2D sonography (-15.7% +/- 11.8%) with CT as the standard (P < .001). The correlation coefficient between 3D sonography and CT (r = 0.98; P < .0001) was better than that between 2D sonography and CT (r = 0.83; P < .0001). In addition, Bland-Altman analysis revealed that the limits of agreement between 3D sonography and CT (-9.7% to 5.1%) were narrower than those between 2D sonography and CT (-45.6% to 9.8%).

CONCLUSIONS

Three-dimensional sonography with a matrix array transducer can significantly reduce renal volume measurement errors and offers a reliable means of determining renal volumes.

Renal length discrepancy by ultrasound is a reliable predictor of an abnormal DMSA scan in children

A renal length discrepancy (RLD) of more than 10 mm by ultrasound (US) is accepted as a potential indicator of an underlying renal pathology; however, there are few supporting data for this in children. Our objective was to determine a cutoff at which RLD on US is a reliable predictor of dimercaptosuccinate acid (DMSA) scan abnormality. We present data from 90 patients who had both renal US and a DMSA scan, as well as DMSA scan results compared with bipolar RLD by US. Positive (PPV) and negative (NPV) predictive values were calculated for renal RLD from 6 to >10 mm. The left kidney was longer in 56%, whereas the right kidney was longer in 37%; their lengths were equal in 8%. For children at all ages, a left kidney longer than the right by >or=10 mm or a right kidney longer than the left by >or=7 mm gave a PPV for DMSA abnormality of 79% and 100%, respectively. In children older than 4 years, if the right kidney was longer by >or=7 mm or if the left kidney was longer by >or=10 mm, the PPVs for DMSA abnormality were 100% and 63%, respectively. In children younger than 4 years, when the right kidney was longer by >or=6 mm or the left was kidney longer by >or=10 mm, the PPV were 86% and 100%, respectively. Thus, children with a right kidney longer than the left by even <10 mm is a reliable predictor of an abnormal DMSA scan.

The effect of fluid intake on renal length measurement in adults

PURPOSE

To evaluate whether oral fluid intake has an effect on renal length as determined with sonography.

METHODS

We studied 524 adult patients who were referred to our ultrasound unit with complaints other than urinary tract symptoms. The mean age of the patients was 44 years (range 17-76). All of the measurements were performed with the patient in the prone position. The renal length of each kidney was measured by the same observer before and after oral fluid intake. Student's t-test was applied for the statistical significance of renal length measurements before and after hydration. Analysis of variance was performed for the effect of age and sex on the renal length measurements.

RESULTS

The mean renal length on the right side was 106.2 +/- 5.5 mm and 107.5 +/- 5.7 mm on the left side before hydration. There was no statistically significant difference between right and left side renal length measurements. After hydration, the mean renal length was 113.5 +/- 6.1 mm on the right side and 114.6 +/- 6.6 mm on the left side. The mean increase in renal length after hydration was statistically significant (P < 0.001) and was 6.8% on the right side and 6.6% on the left side. Sex and age did not affect the measurements significantly.

CONCLUSIONS

Oral fluid intake causes a statistically significant increase in renal length. This observation should be taken into consideration when renal length measurements are clinicallly important.

Evaluation of renal growth by magnetic resonance imaging and computerized tomography volumes

PURPOSE

Magnetic resonance imaging (MRI) and computerized tomography (CT) are commonly used to image complex medical conditions but limited data have been reported concerning normal renal volumetric measurement with these imaging techniques. We examined whether normative renal growth curves could be constructed from data derived from these imaging modalities, and from these curves assessed normal and abnormal renal development.

MATERIALS AND METHODS

Patients who had undergone prior renal MRI or CT were identified. Total renal volume and renal cortical fraction (CF, cortical/total volume) were calculated, and growth curves were derived. To examine the curve utility for abnormal growth assessment, renal ultrasonography of children with reflux nephropathy was examined, and MRI and radionuclide scans were compared.

RESULTS

A total of 60 patients 2 months to 39 years old who underwent MRI were included in the growth curve. The CF of the 120 kidneys was 75.8 +/- 4.3% and independent of sex and age. In 19 patients with vesicoureteral reflux 13 kidneys had cortical scarring, and the CF was decreased (p <0.001, 63.65 +/- 5.72%), indicating disproportionate cortical loss. No difference between CF for normal and vesicoureteral reflux unscarred kidneys was found. Differential renal function on radionuclide study correlated highly with MRI renal volume (r = 0.91). CT was performed in 70 children 1 to 15 years old (mean age 7.9) volume correlated with age and renal length, and the left kidney was larger than right kidney on MRI and CT.

CONCLUSIONS

Normative renal growth curves can be constructed from CT and MRI derived renal volumes. Cortical fraction is consistent, and sex and age independent. In reflux nephropathy the CF is reduced and renal differential function on nuclear scan correlates with MRI derived differential volume. This concept may be useful for predicting abnormal renal growth and differential function.

The renal length nomogram: multivariable approach

PURPOSE

We built a multivariate renal length nomogram based on ultrasound measurements in pediatric patients with normal renal anatomy.

MATERIALS AND METHODS

Included in the study were 707 children 1 week to 18 years old without vesicoureteral reflux, urinary obstruction or other known anatomical anomalies. Renal length was compared among subgroups of children. Multivariate regression approach was used to model renal length, incorporating important demographic variables.

RESULTS

Subgroup comparisons of renal lengths showed diverse patterns of renal length differences in children with various demographic characteristics. In addition to age, factors significant in the multivariate nomogram model of renal length included gender, race, weight and height.

CONCLUSIONS

These results show that renal length is not only age dependent, but also significantly correlates with other important demographic variables. Variability in renal length can be better described by multivariate analysis. The multivariate approach provides clinically useful information regarding renal outcomes in individuals. The ability to compare renal length among patient subgroups receiving different interventions adds additional usefulness to this approach.

Renal volume measurements: accuracy and repeatability of US compared with that of MR imaging

PURPOSE

To determine the accuracy and repeatability of ultrasonography (US) with the ellipsoid formula in calculating the renal volume.

MATERIALS AND METHODS

The renal volumes in 20 volunteers aged 19-51 years were determined by using US with the ellipsoid formula and magnetic resonance (MR) imaging with the voxel-count method by two independent observers for each modality. The observers performed all measurements twice, with an interval between the first and second examinations. The voxel-count method was the reference standard. Repeatability was evaluated by calculating the SD of the difference (method of Bland and Altman).

RESULTS

Renal volume was underestimated with US by 45 mL (25%) on average. A comparable underestimation was found when the ellipsoid formula was applied to MR images. This indicates that the inaccuracy of US renal volume measurements (a) occurred because the kidney does not resemble an ellipsoid and (b) was not primarily related to the imaging modality. Intra- and interobserver variations in US volume measurements were poor; the SD of the difference was 21-32 mL. For comparison, the SD of the difference in reference-standard measurements was 5-10 mL.

CONCLUSION

Use of US with the ellipsoid formula is not appropriate for accurate and reproducible calculation of renal volume.

In vitro measurement of kidney size: comparison of ultrasonography and MRI

In this in vitro study, the accuracy and repeatability of magnetic resonance imaging (MRI) and ultrasound (US) in assessing renal length and volume were determined. US and MR images of 20 cadaver pig kidneys were obtained twice and evaluated by two observers for each modality. The fluid displacement method provided the "gold standard." Renal volumes were calculated from the US and MR images using the ellipsoid formula. Additional volume calculations after segmentation of the kidney on MR images were done using the voxel-count method. Volumes calculated with the ellipsoid formula resulted in an average of 24% underestimation (range 5%-48%) of the renal volume for both US and MRI. With the voxel-count method, no significant deviation from the true renal volume was encountered. Repeatability was also greatest with the voxel-count method. Measuring renal length, repeatability was, again, better with MRI compared to US. For reliable calculation of renal size in vitro, MRI with use of the voxel-count method is preferred.

Long-term followup of renal morphology and function in children with recurrent pyelonephritis

Renal morphology and function were evaluated in 161 children with recurrent pyelonephritis with or without vesicoureteral reflux and with or without scarred or small kidneys. The patients were followed for 1 to 21 years. Renal function was determined by glomerular filtration rate and effective renal plasma flow by clearances of inulin and paraaminohippuric acid. Of 105 children with normal kidneys originally small or scarred kidneys developed in 37, of whom 22 had grade III or greater vesicoureteral reflux, while small kidneys developed in 13 of 29 children with renal scarring originally. Of the 37 children with normal kidneys originally renal parenchymal scarring developed in 14 after the age of 4 to 5 years. Glomerular filtration rate was already < -2 standard deviations of that of controls in 51% of the patients at the first and in 53% at the last investigation of renal function. Of these patients with a glomerular filtration rate of < -2 standard deviations 69% had small or parenchymally reduced kidneys most of whom had the first pyelonephritis episode before age 3 years. Patients with small kidneys had a lower glomerular filtration rate than those with normal sized kidneys, whether scarred or not. The low glomerular filtration rate and its subsequent further reduction were related to kidney size and not to the presence or degree of vesicoureteral reflux. However, in individual patients the rate of functional deterioration could not be predicted from the radiological findings. Patients with bilateral small kidneys seemed to show the greatest decrease in glomerular filtration rate during followup as did those with grade III or greater reflux undergoing surgery bilaterally and those patients also had a lower glomerular filtration rate at the last investigation compared to patients not undergoing surgery. In conclusion, renal functional damage seems to occur early in the course of the disease and seems to be related to kidney size but there is a further slow progression with reduction in renal function which occurs, although this is difficult to predict from the radiological changes in individual patients. Therefore, patients with recurrent pyelonephritis should be followed regularly by glomerular filtration rate determination using an accurate method.

Kidney function in adults born with unilateral renal agenesis or nephrectomized in childhood

We have evaluated the long-term prognosis in an unselected group of adult patients either uni-nephrectomized in childhood because of hydronephrosis or born with unilateral renal agenesis. Thirty-six patients aged 7-47 years were followed for 7-40 years. In 23 control subjects aged 20-47 years the glomerular filtration rate (GFR) and the p-aminohippuric acid clearance (CPAH) did not change significantly with age. In patients with a single kidney the size of that kidney was larger and GFR and CPAH were higher than single kidney values in control subjects. However, in patients with a single kidney since childhood the GFR and the CPAH declined slowly but significantly during the follow-up period. Significant microalbuminuria occurred in 47% of the patients with a single kidney and was more frequent with a longer follow-up period. No patient had renal insufficiency or a marked increase in arterial blood pressure. We conclude that in patients with a single kidney since childhood the long-term prognosis is good, but the late decrease in GFR and increase in albumin excretion may indicate a moderate risk for premature renal damage.

Comparison between renal parenchymal sonographic volume, renal parenchymal urographic area, glomerular filtration rate and renal plasma flow in children

A comparison of renal size, expressed as ultrasonographic renal parenchymal volume and urographic renal parenchymal area, and renal function, measured as glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), was made in two groups of children: (1) 21 patients with normal urograms and no signs of current disease and (2) 26 children with recurrent urinary tract infections or asymptomatic bacteriuria. Renal parenchymal volume was calculated using a water delay ultrasonographic device (Octoson). Renal parenchymal area was measured urographically. GFR and ERPF were determined from the clearances of inulin and PAH, respectively. In both groups a good correlation was found between both GFR and ERPF and total renal parenchymal volume as well as renal parenchymal area. The determination of renal parenchymal volume could possibly replace the determination of GFR and ERPF in healthy children and in children with urinary tract infections with normal and abnormal urograms.

Kidney dimensions in ultrasound compared to somatometric parameters in normal children

In 196 children aged between 4 weeks and 16 2/12 years a sonographic investigation of kidneys was performed and put into relation to somatometric data including bodyweight (BW) bodylength (BL), length of the trunk and the upper and the lower limb, breadth of thorax and pelvic, head circumference, maximum cranial length and maximum cranial breadth. None of the children had signs of renal disorder. Morphometric data, as kidney length, width, depth, parenchymal areas in longitudinal and transverse sections and the prolate ellipsoid volume (PEV) were documented. The children were divided into five groups (group 1: 2-6 months, group 2: 6-31 months, group 3: 31-99 months, group 4: 99-131 months, group 5: 131-194 months). Mean values of all parameters were calculated. For each group a multiple regression analysis was performed and a regression equation of kidney length, parenchymal areas and volume was established. This method allows an individual determination of renal size and parenchymal mass.