Relationship between area and function of the kidney in well defined childhood nephropathies

How reliable is renal ultrasound to measure renal length and volume in patients with chronic kidney disease compared with magnetic resonance imaging?

Background

Renal length, volume, and parenchymal thickness are important clinical parameters, yet data concerning the accuracy and reproducibility of ultrasound (US)-based renal length and volume assessment in patients with chronic kidney disease (CKD) are scarce.

Purpose

To establish whether renal length, volume, and parenchymal thickness can be reliably measured with renal US in patients with CKD.

Material and Methods

All participants underwent renal US, immediately followed by 3-T magnetic resonance imaging (MRI). Renal length, width, transverse diameter, and parenchyma thickness were measured with both methods; renal volume was calculated using the ellipsoid formula. A total of 45 patients with CKD (eGFR [mean ± SD] 57.4 ± 4.4 mL/min/1.73 m2) and 46 participants without CKD (eGFR 97.0 ± 2.4 mL/min/1.73 m2) were included.

Results

US-measured renal length correlated strongly with MRI-measured renal length in no-CKD patients (Spearman’s r = 0.83 and 0.85 for the right and left kidney, respectively; P < 0.005) and CKD patients (r = 0.89 and 0.92 for the right and left kidney, respectively; P < 0.005). There was a significant but weaker correlation between MRI- and US-measured right and left renal volume (r = 0.72, P < 0.005) in no-CKD (r = 0.74 and r = 0.72, respectively; for both: P < 0.005) and CKD patients (r = 0.83 and 0.85, P < 0.005). Weak to moderate correlations were found for parenchyma thickness for the right (CKD group: r = 0.29, no-CKD: r = 0.23; for both: P < 0.05) and left kidney (CKD: r = 0.52, no-CKD group: r = 0.37, P < 0.05). Both intra-observer (Pearson’s correlations of 0.82 for the right and 0.89 for the left kidney) and inter-observer (Lin’s correlation coefficient of 0.90 for the right and 0.82 for the left kidney) reproducibility of US-assessed renal length was high.

Conclusions

US-based assessment of renal length in CKD patients is comparable to MRI measures. Both intra- and inter-observer reproducibility of US-assessed renal length in CKD patients are high. Measurements of US renal volume and parenchymal thickness should, however, be interpreted with caution.

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.

Measurement of renal dimensions in vivo: A critical appraisal

Kidney volume is regarded as the most precise indicator of kidney size. However, volume assessment is not widely used clinically because its measurement is difficult due to the complex kidney shape. Apart from the conventional methods of measurement of renal dimensions from X-rays, ultrasound scan, computed tomography scan and magnetic resonance imaging have evolved as the three best modalities for this purpose currently. Assessment of kidney size should also be made individually since many factors like body mass index, height, gender, age, position of kidneys, sex, stenoses and number of renal arteries influence the measurements. In this paper, we have critically analysed the advantages and disadvantages of the various methods of renal morphometry, by reviewing the literature spanning over the period of 1976 - 2009.

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.

P-fimbriated Escherichia coli in adults with renal scarring and pyelonephritis

The commonest organism in urinary tract infections (UTI) is Escherichia coli. Pyelonephritogenic E.coli strains possess P-fimbriae which firmly attach to uroepithelial cells by recognition of a carbohydrate structure, alpha-D-Galp-(1-4)-beta-D-Galp, which is confined within all glycosphingolipids related to the human P-blood group antigens. Several investigators have studied virulence properties of E.coli and host resistance in relation to UTI. Uroepithelial cells from children and women with recurrent UTI have an increased capacity to bind E.coli. In contrast to previous studies the present one deals with patients with renal scarring, who constitute the major risk group among patients with UTI. P-fimbriae mediated binding to uroepithelial cells was studied and the risk of recurrent UTI in patients with renal scarring was determined. Ninety per cent of the E.coli isolates from female patients with acute non-obstructive pyelonephritis in this study possess P-fimbriae (I). The fecal E.coli colonies obtained from these patients were P-fimbriated in 55% compared to 11% of the fecal E.coli colonies from healthy controls. The P-blood group distribution in 56 female patients with renal scarring and a history of febrile UTI was the same as in a control group of 39 healthy subjects (II). A history of recurrent and/or early infections did not increase the percentage of the P1 blood group phenotype. Forty-nine female patients with renal scarring were prospectively investigated for the incidence of symptomatic UTI in relation to fecal colonization with P-fimbriated E.coli (III). Fifty-three per cent of the patients had altogether 65 episodes of symptomatic UTI during the three-year follow-up (0.036 infections per month). Eight patients (16%) had nine attacks of acute pyelonephritis and 4/5 of the tested E.coli strains from these patients were P-fimbriated. No relationship was demonstrated between the presence of P-fimbriated E.coli in the fecal flora and the development of subsequent acute pyelonephritis. The binding of P-fimbriated E.coli to uroepithelial cells from 19 female patients with renal scarring was studied with the fluorescence-activated cell sorting (FACS) analysis (IV). The uroepithelial cells from the patients with renal scarring exhibited a significantly higher binding capacity (p less than 0.01) than uroepithelial cells from healthy controls. Furthermore, uroepithelial cells from the patients with renal scarring and kidney insufficiency had a higher availability of P-fimbriae receptors on their uroepithelial cells than cells obtained from patients with renal scarring and normal renal function (r = -0.75, p less than 0.001) (V).(ABSTRACT TRUNCATED AT 400 WORDS)

Renal growth in children with severe vesicoureteral reflux: 10-year prospective study of medical and surgical treatment: the International Reflux Study in Children (European branch)

PURPOSE

To determine whether medical or surgical treatment better promotes renal growth in children with severe vesicoureteric reflux (VUR) and to examine factors influencing renal growth.

MATERIALS AND METHODS

Three hundred two children younger than 11 years with urinary tract infection and grade III or IV VUR were randomly assigned to surgical (n = 149) or medical (n = 153) treatment and were followed up at serial intravenous urography for up to 5 years; 223, for up to 10 years (surgical, n = 110; medical, n = 113). Renal size was measured planimetrically on serial intravenous urograms and was related to the virtual height of L1 through L3 by expressing it as an SD score.

RESULTS

There was no significant difference in mean renal growth between patients treated surgically or those treated medically after 5- or 10-year follow-up. Bilateral renal size of 80 surgical and 75 medical patients remained within 1 SD score. In patients entering the study at 2 years of age or younger and in those with grade IV VUR, bilateral VUR, or renal scars, there was a trend toward improved renal growth in those treated medically, but this finding was not statistically significant. When renal scarring or thin parenchyma was unilateral, the affected kidney grew less well, irrespective of treatment. Bilateral renal scarring was usually asymmetrical, with a corresponding effect on renal growth.

CONCLUSION

There was no significant difference in renal growth during 10 years between surgical and medical treatment in patients with severe reflux.

Girls prone to urinary infections followed into adulthood. Indices of renal disease

This study describes blood pressure and renal function, as well as indices of renal disease, in females with and without renal scarring followed from their first urinary tract infection (UTI) in childhood. Of the 111 patients with a median follow-up time of 15 years, 54 had renal scarring (reflux nephropathy) on urography, which was severe in 19 and moderate in 35. The glomerular filtration rate was lower in patients with severe renal scarring and correlated with renal area on urography. However, the filtration rate was decreased below the lower reference limit in only 7 patients, with a lowest value of 70 ml/min per 1.73 m2. The diastolic blood pressure was higher in women with severe scarring. Hypertension of at least 140/90 mmHg was diagnosed in 3 of 54 (5.5%) females with renal scarring, 2 before and 1 at the follow-up examination. The excretion of albumin in urine was low and not correlated to filtration rate. Tubular enzymes in urine were similar in all groups. Thus the renal function was well preserved and the incidence of hypertension low. Within this range of renal function, the level of albumin in urine did not predict the degree of renal scarring.

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.

Results of a randomized clinical trial of medical versus surgical management of infants and children with grades III and IV primary vesicoureteral reflux (United States). The International Reflux Study in Children

A total of 132 infants and children with grades III and IV primary vesicoureteral reflux was entered into a prospective trial comparing medical to surgical management. Inclusion criteria were an age not exceeding 10 years and a glomerular filtration rate of at least 70 ml. per minute per 1.73 m.2. Children with significant urinary tract malformations and clinical signs/symptoms of dysfunctional voiding were not accepted into the trial. Medical therapy consisted of continuous low dose antibiotic prophylaxis until vesicoureteral reflux resolved. The type of surgical procedure used for the correction of reflux was left to the discretion of the surgeon. Outcome variables included the appearance or progression of renal lesions, rate of renal growth, recurrence rate of urinary tract infection or pyelonephritis, changes in total kidney glomerular filtration rate, development of hypertension and resolution rate of vesicoureteral reflux. Followup at 6, 18, 36 and 54 months after entry included, in addition to history and physical examination, voiding cystourethrography, excretory urography and a urine culture. Of the patients 68 were allocated to the medical group and 64 to the surgical group. They were stratified for age, sex and preexisting renal scarring. Of the patients 10% were boys, 47% were between 2 and 6 years old at entry, 93% had a history of pyelonephritis, 67% had either scarring or thinning of the parenchyma at entry, 87% had grade IV vesicoureteral reflux in at least 1 unit and 56% had bilateral reflux. There were no significant differences in the frequency distribution of entry characteristics between the patients allocated to either group. New renal scarring developed in 22% of medical and 31% of surgical patients (p < 0.4). Growth of kidneys with grade IV vesicoureteral reflux was slightly less than normal in the medical (-0.67 +/- 0.15 standard deviation) and surgical (-0.42 +/- 0.11 standard deviation) groups (p < 0.7). Pyelonephritis occurred in 15 medical patients versus 5 surgical patients (p < 0.05). There was no significant change in glomerular filtration rate within each treatment group and no difference in glomerular filtration rate between groups. No patient had hypertension during the followup period. The disappearance rate of vesicoureteral reflux in patients with grade IV reflux was approximately 8% per year. Of the medical patients 75% still had vesicoureteral reflux after 3 years of observation.(ABSTRACT TRUNCATED AT 400 WORDS)

Long-term prognosis of post-infectious renal scarring in relation to radiological findings in childhood--a 27-year follow-up

In a previous report the long-term prognosis of 30 patients with renal scarring after pyelonephritis in childhood was described. In this study, we have related the extent of renal scarring present in childhood to the conditions in early adulthood. A radiological progression of scarring from childhood to adulthood was seen in one-third of the kidneys. The 7 patients with bilateral scarring in childhood had a smaller renal area, lower glomerular filtration rate and higher plasma vasopressin at follow-up than 13 healthy controls. The 20 patients who had unilateral scarring in childhood had a smaller renal area, lower glomerular filtration rate, higher diastolic blood pressure and higher plasma renin at follow-up than controls; 4 had hypertension. The most important finding was that children with unilateral disease are at risk of serious long-term complications. Filtration fraction at follow-up was higher in patients with extensive renal scarring in childhood compared with those with a normal renal area or small scars in childhood (r = -0.43, P less than 0.05). This may indicate glomerular hyperfiltration by remnant glomeruli. This paper emphasizes t the potential seriousness of childhood urinary tract infections especially when early infantile infections are overlooked. A follow-up of more than 4 decades may be necessary before the ultimate prognosis can be established, especially in patients with unilateral renal disease. It is advised that most patients with post-infectious renal scars are followed as high-risk patients, and that treatment continuity is established between paediatricians, nephrologists and, when required, obstetricians.

Covert bacteriuria: long term follow up

In a longitudinal prospective study 58 schoolgirls with covert bacteriuria were followed up for an average of 11.2 years (range 8.8 to 13.5 years). Intravenous urography was carried out at the start of the study (aged 4 to 11 years) and after completion of the follow up period (aged 14.8 to 22.3 years). After random allocation 27 of these girls received intermittent treatment for covert bacteriuria for the first four years and the control group received no treatment. The effect of covert bacteriuria, treatment, vesicoureteric reflux, and reflux nephropathy at presentation on the final renal length, progression of scarring, and development of new scars was analysed. No new scars were found in girls with bilaterally normal kidneys. In girls with reflux nephropathy, three kidneys showed progression of existing scars and two kidneys developed new scars. It was shown that final renal length was not influenced by vesicoureteric reflux or treatment, but reduced renal length at final assessment was associated with the presence of kidney scarring at initial assessment.

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.

A computerized system for handling renal size measurements from urograms

The size of a kidney, as measured on a urogram, is a sensitive indicator of renal damage in a child with urinary tract infection and renal surface area correlates well with glomerular filtration rate. Sequential measurements can be invaluable in evaluating the efficacy of a regimen of treatment. A system utilizing a personal microcomputer has been developed to facilitate the measuring procedure and the handling and analysis of data.

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.

A comparative study of size and function of the remnant kidney in patients nephrectomized in childhood for Wilms' tumor and hydronephrosis

To obtain more information about the natural history of compensatory renal hypertrophy beginning in childhood we traced those who were nephrectomized in childhood for Wilm's tumor (W) and hydronephrosis (Hn) between 1950 and 1978 at one department of surgery in Stockholm. All W patients had received treatment that suppresses cellular division. None of the patients were in renal failure or treated with antihypertensive drugs. All the patients in the follow-up study (22 W, 15 Hn) had a normal contralateral kidney at nephrectomy. Five healthy adults served as controls. The kidney was enlarged in both Hn (142%) and W (125%), but significantly larger in Hn than in W. Renal compensatory growth in W was retarded during the first two years after nephrectomy. The glomerular filtration rate (GFR) was 92% of control in Hn and 82% of control in W. The GFR did not seem to decline with a longer follow-up time in any of the groups. PAH clearance was the same in Hn and W. Albumin excretion was significantly higher in Hn than in W, but not significantly higher in W than in controls. The highest albumin excretion rates were found among the Hn patients with long follow-up time. The results suggest that the large increases in size and function that follow childhood nephrectomy can be blunted by antimitotic agents.

Renal involvement in the Laurence-Moon-Biedl syndrome. Functional and radiological studies

The renal abnormality of the Laurence-Moon-Biedl syndrome (LMBS) was investigated in six patients. The glomerular filtration rate (CIn) and the effective renal plasma flow (CPAH) were evaluated by standard clearance techniques and the single injection method, and the maximal concentration capacity was estimated by the ddAVP test. The kidney surface area and length were related to the body surface area, as well as the lumbar vertebrae L1-L3, and the relationship with the GFR was studied. All six patients showed renal abnormalities: Five had small kidneys with reduced GFR and concentrating ability, and one had hyperaminoaciduria (but normal kidney size). Two patients developed terminal renal failure (one of them was successfully transplanted), illustrating the progressive character of the renal lesion. Three of the patients had had recurrent urinary tract infections, but the radiological changes of the kidneys were of the same character as in the others (symmetrical and irregular parenchymal reduction, and blunting and clubbing of the calyces). Since renal abnormalities, with considerable risk for progression to terminal renal failure, are common in the LMBS, regular urine cultures and blood pressure measurements are probably of great importance.

Vesicoureteral reflux and reflux nephropathy

Vesicoureteral reflux (VUR) is mainly a primary phenomenon due to incompetence of the ureterovesical junction, mostly affecting a pediatric population. During micturition cystourethrography (MCU) reflux into the kidney--intrarenal reflux (IRR)--is occasionally seen. In areas with IRR the kidney surface may subsequently be depressed and the papillae retracted (reflux nephropathy (RN]. VUR may lead to hypertension and/or end-stage renal failure. Most commonly, VUR is discovered during evaluation for urinary tract infection, but it may also be present in patients with hypertension, toxemia of pregnancy, chronic renal failure and proteinuria, and it may be found in siblings of patients with VUR. For the time being VUR is demonstrated at radiographic MCU, whereas RN is diagnosed by demonstration of focal scars and of abnormal parenchymal thickness at urography. In children with VUR and no abnormalities of calyces or parenchymal defects standardized measurement of the parenchymal thickness at three sites may identify kidneys which are likely to develop focal scars. Quantitation of focal scarring should be performed in connection with a measure of the overall kidney size. The occurrence of IRR is dependent of the papillary morphology, intrapelvic pressure and urine flow. There may be an important relationship between renal ischemia and IRR in producing a 'vicious circle of deleterious effects' which, combined with parenchymal extravasation, may lead to RN. Treatment of VUR includes medical and surgical management. Since renal scarring may occur in infancy, prevention should focus on infants and young children. Infants and young children with severe VUR may have normal urograms. Therefore a MCU should also be performed, preferably with the recommended standardized technique.

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

A comparison of the relationship that might exist between ultrasonographically calculated renal parenchymal volume and renal parenchymal area assessed from urography and also between renal parenchymal volume and kidney function was conducted in a series of 26 children with recurrent urinary tract infection or asymptomatic bacteriuria. Glomerular filtration rate (GFR) was determined by the clearance of inulin, renal parenchymal area was measured from urography and renal parenchymal volume was calculated from sequential longitudinal scans of the kidney using an automated water-delay ultrasonographic equipment (Octoson). High correlation was found between 1) renal parenchymal volume and GFR, 2) renal parenchymal volume and renal parenchymal area and 3) renal parenchymal area and GFR. Octoson ultrasonographic determination of renal parenchymal volume is a reliable method to evaluate glomerular filtration rate and renal parenchymal area in children with recurrent urinary tract infections and asymptomatic bacteriuria.

Renoprival growth following treatment of unilateral Wilms' tumour

The renal growth pattern following uninephrectomy for Wilms' tumour was analysed in 18 boys and 18 girls by means of a comparison between renal parenchymal and body surface area. No straightforward correlation was noted between age at nephrectomy, chemo- and radiation therapy applied, and subsequent renoprival dimensions. Five years on average after operation, a mean renal size corresponding to approximately 125 per cent of the normal for one of two healthy kidneys was recorded. However, wide variations in size were observed, but only 10 patients had a compensatory growth of the remaining kidney equivalent to that seen in patients nephrectomized for unilateral, non-malignant renal disease.

Age as a main determinant of renal functional damage in urinary tract infection

Renal function was studied in 61 girls suffering from recurrent urinary tract infections, with at least one febrile infection. Clearance of inulin was determined. Intravenous urography and micturating cystourethrography were performed 1-6 months after the first infection and 0-6 months before or after the function test. A low glomerular filtration rate (GFR) was found only among children with their first pyelonephritis before the age of 3 years. A low GFR was found mostly in patients with small or scarred kidneys but was also seen in a few patients with normal intravenous urographs. Low GFR as well as radiologically small kidneys at the time of the function test were found independently of the presence or grade of vesicoureteral reflux at first infection. Patients with early onset pyelonephritis (before age 3 years) had a low capacity for early compensatory hypertrophy in contrast to patients with late onset pyelonephritis.

The effect of experimental hydronephrosis on clearance data

Partial obstruction of one ureter was created in newborn rats and its effects were studied in the adult rat. The obstructed renal pelvis was found to be enlarged 2-3 times. The weight of the kidney on this side was 85% of the contralateral one. Inulin clearance was measured in a way, which allowed comparison between the conventional technique and a modified technique, designed to circumvent the dilution in the enlarged pelvis. With the conventional technique, filtration was 32% of that in the contralateral kidney, whereas with the new technique true filtration of the hydronephrotic kidney was 82% (p less than 0.001). The modified technique is evaluated and the implications of the functional results are discussed.

Growth of renoprivals following uninephrectomy for Wilms' tumour: application and suitability of a method of assessment

In an attempt to evaluate the long-term renoprival growth in patients uni-nephrectomized for Wilms' tumour, renal length was related to the length of the lumbar segment L1-L3. The results of this study indicated that spinal growth retardation, secondary to applied adjuvant treatment, invalidated employment of the method for this particular purpose. A computerized analysis showed no straight-forward correlation between age at operation, chemotherapy utilized, irradiation and the post-treatment renoprival growth as established by substitution of the observed L1-L3 length with a mathematically corrected value. Emergent figures exclude significant compensatory growth of the remaining kidney.

Compensatory kidney growth in children with urinary tract infection and unilateral renal scarring: an epidemiologic study

Compensatory renal growth was estimated from repeated urograms over 8 to 15 years in 26 children with urinary tract infection and unilateral renal scarring. These children were derived from an unselected series of 596 patients followed from their first symptomatic urinary tract infection. Renal size was assessed from the renal area, length, and parenchymal thickness. The renal area proved to be a good measure of the compensatory growth of the unscarred kidney as well as of the loss of substance of the scarred kidney. In this series of children, who had been closely supervised from the time of their first infection, unilateral renal scarring was well compensated for by hypertrophy of the contralateral kidney. Thus, the total renal parenchymal area 8 to 15 years after the first investigation was 98 to 99% of the expected normal area. Interestingly, a conspicuous growth spurt was observed at puberty in some of the scarred kidneys, sometimes a decade after the original damage. Prognosis was not influenced by sex, age at onset, or complications such as vesicoureteric reflux and frequent febrile recurrences. Reflux with dilatation was compatible with compensatory renal growth. We conclude that acute febrile pyelonephritis in childhood carries a good prognosis with regard to preservation of renal parenchyma and level of GFR, if diagnosis and treatment are prompt and long-term supervision is provided.

Renal function in acute febrile urinary tract infection in children: pathophysiologic aspects on the reduced concentrating capacity

In an attempt to elucidate the reduced concentrating capacity in acute pyelonephritis, we studied the renal function in 14 children, 5 to 16 years of age. Clearance of inulin, PAH, and free water, urinary sodium excretion, and maximal urine osmolality after 18 hours of thirst have been determined at and within 10 months after infection. Glomerular filtration rate and renal plasma flow were found to be increased during infection and normalized after infection. Urinary sodium excretion, distal sodium delivery, and maximal urine osmolality were decreased during infection and increased afterwards. Kidney size was also increased during infection. It is postulated that the reduced concentrating capacity is due to a washout effect mediated by an increased medullary blood flow and to a low distal tubular sodium delivery.

Long-time effect of large vesicoureteral reflux with or without urinary tract infection

In children more than one year old the growth rate of the renal parenchyma is delayed if the kidney has a large reflux-ureter and is exposed to urinary tract infection. The growth rate of the parenchyma is normal, if the kidney has a large reflux-ureter but no infection. However, since moderate reduction of the renal parenchyma is often observed in patients with large reflux-ureter but without a history of urinary tract infection, it is concluded that a large reflux may cause back pressure injury on the kidney during infancy but, in children more than one year old, will cause renal growth retardation and renal scarring only be predisposing to pyelonephritis.

Occurrence of reflux in children with ureteral jets

The urograms of 186 boys and 145 girls were scrutinized in order to reveal the incidence of ureteral jets demonstable during intravenous pyelography (IVP). In this series a unilateral jet was observed in 26 cases and a bilateral jet in 6 cases. Ureteral jets were almost three times as common in patients with normal urograms compared with those revealing urinary abnormalities. The incidence of a positive jet sign, usually unilateral, varies with the employed technique of examination, but the highest incidence in routine IVP seems to be about 30%. Although infrequent, significant ipsilateral vesico-ureteral reflux (VUR) may occur. This fact together with the reported low rate of bilateral jets restricts the value or Unilateral jets being used as an indicator of absence of gross VUR. The need for micturition cysto-urethography (MCU) at the uro-radiological work-up remains unchallenged.

Size of the unaffected kidney in children with unilateral hydronephrosis

Children with unilateral hydronephrosis, but without evidently decreased excretion of urographic contrast medium, generally had enlargement of the unaffected mate kidney, indicating reduced function of the hydronephrotic kidney.

Kidney split function in children. A comparative study between renography and planimetry from urography

The suitability of the background-subtracted renogram as a method for separate kidney function in children was evaluated by comparison with planimetry of the individual renal parenchymal area measured from urography. In different groups of renal disorders the total kidney function as reflected by the glomerular filtration rate has been compared with the sum of right and left renal parenchymal areas. The percentage side distribution of kidney function estimated from the renogram combined with measurements of total glomerular filtration rate has been correlated to individual renal parenchymal area. A good correlation was found for both total and separate measurements. A moderate scatter around the regression lines has to be taken into consideration when kidney function is judged from planimetry. A highly significant correlation was observed between renography and planimetry for the percentage distribution of kidney function, indicating that both methods are well suited for determining the side distribution of kidney function. For calculation of individual kidney function, combination of renography and 51Cr-EDTA-clearance offers a reliable method with a modest dose of irradiation.

Kidney size in normal children measured by sonography

Kidney length and depth were measured by sonography in 46 normal children fro 0 to 16 years of age. Sonography was used to obtain kidney measurements without the known magnification caused by factors of chemical and photographic nature seen by urography. The results of our study were used to control the age-adapted equipment for renography in children. There was a good correlation between kidney length and depth and variables like age, weight, height and body surface area. The best values were found in the correlations to body surface area. We could confirm the previous findings by other methods of kidney size measurements in children that there is no significant difference in kidney length between boys and girls. The left kidney is slightly longer than the right one and the kidney centre distance is slightly but significantly larger on the left side. No such difference was present in the distance skin to kidney surface.