Renal parenchymal thickness and urinary protein levels in patients with ureteropelvic junction obstruction after nephrostomy placement

The use of urinary osmolality to evaluate postoperative renal function in children with ureteropelvic junction obstruction

INTRODUCTION

Split renal function measured in a diuretic renogram is the most popular tool in initial assessment and follow-up of patients with ureteropelvic junction obstruction (UPJO). This study aims to evaluate the use of maximum urinary osmolality after desmopressin administration (DDAVP) to detect renal dysfunction.

PATIENTS AND METHODS

56 children (33 males, 23 females) diagnosed with UPJO underwent quantification of the maximum urinary osmolality (UOsm) at diagnosis. 41 of these children (28 males, 13 females) underwent surgery for UPJO and quantification of the UOsm before and after the surgical intervention (six to 18 months postoperatively) and were included in this longitudinal study.

RESULTS AND DISCUSSION

At diagnosis, UOsm measured after desmopressin administration was abnormal in 64% of patients. After surgical intervention, this rate decreased to 53%. At initial assessment, high creatinine levels were found in 32% of infants younger than one year of age. Albumin/Cr and NAG/Cr ratios were elevated in 12% and 7% of cases, respectively. After surgical intervention, an improvement in the NAG/creatinine ratio and creatinine levels was observed. Preoperative split renal function of the affected kidney was less than 45% in 39% of cases, normal in 44%, and greater than 55% in 17%; in these three subgroups, no differences in renal function markers were found.

CONCLUSIONS

The most sensitive parameter to detect alterations in renal function in children with UPJO is the UOsm and, therefore, the most useful in the follow-up after surgery. No correlation was found between other functional and morphological parameters obtained on renal ultrasound and renogram.

Renal Hemodynamic Changes and Postsurgical Recovery in Children Treated for Ureteropelvic Junction Obstruction

OBJECTIVE

The aims of the study were to measure renal hemodynamic indexes and to evaluate postsurgical recovery in children diagnosed with obstructive hydronephrosis using color Doppler ultrasound.

METHODS

This study enrolled 36 patients with ureteropelvic junction obstruction who underwent Anderson-Hynes pyeloplasty. The peak systolic velocity (PSV) and the resistive index (RI) of the main renal arteries (MRAs) and interlobar renal arteries (IRAs) were measured using color Doppler ultrasound. Renal hemodynamic indexes were measured before surgery and 2, 4, 6, 8, 10, 12, 14, and 16 weeks after surgery.

RESULTS

Split renal function and renal parenchymal thickness were positively correlated with PSV and negatively correlated with RI. Anterior-posterior diameter had no significant correlation with PSV or RI. The PSV in MRAs and IRAs were lower than those of the contralateral kidneys but increased after surgery. Anderson-Hynes pyeloplasty was successfully performed in all patients, including one patient whose kidney was removed 16 weeks after surgery. The RI in the MRAs and IRAs were higher than those of the contralateral kidneys but decreased within 2 weeks after surgery. Peak systolic velocity and RI were still atypical 16 weeks after surgery. The hemodynamic index of the nonfunctional kidney did not show improvement after surgery.

CONCLUSIONS

Peak systolic velocity and RI were correlated with renal function and renal parenchymal thickness but were not correlated with dilatation of the renal pelvis. Peak systolic velocity increased whereas RI decreased after surgery and were stable at 8 weeks, but remained abnormal 16 weeks after surgery. Hemodynamic measurements may be a useful and convenient method to evaluate surgical outcomes after Anderson-Hynes pyeloplasty.

Genetic and environmental variance of renal parenchymal thickness: a twin study

AIM

To estimate heritability and environmental effects on renal parenchymal thickness.

METHODS

In this twin study, renal parenchymal thickness of 98 Hungarian healthy adult twin pairs (68 monozygotic, 30 dizygotic) without kidney disease was measured bilaterally using renal ultrasound with Esaote MyLab 70X ultrasound machine with low-frequency curved transducers (1-8 MHz).

RESULTS

In both monozygotic and dizygotic group there were more women (76.5%). Mean right and left renal parenchymal thickness was 1.32±0.33 cm and 1.62±0.31 cm, respectively. Age- and sex-adjusted heritability of renal parenchymal thickness was 0.0% (95% confidence interval, 0.0 to 50.2%), shared and unshared environmental factor was 30.2% (4.1 to 55.9%) and 69.8% (45.8 to 89.5%), respectively.

CONCLUSION

This study shows a negligible role of heritability and an important role of environmental effects in developing renal parenchymal thickness, emphasizing the importance of lifestyle for primary prevention.

Renal parenchymal thickness as a measure of renal growth in low-birth-weight infants versus normal-birth-weight infants

Low birth weight (LBW, <2500 g) infants have a reduced number of glomeruli and nephrons and, therefore, smaller kidneys. The purpose of this pilot study was to determine whether renal parenchymal thickness might be a better indicator of renal growth. We carried out a pilot study over 12 mo to determine whether renal parenchymal thickness could be used to detect differences in renal growth between LBW and normal birth weight (NBW, 2500-4500 g) infants. Thirty-eight term infants (12 LBW and 26 NBW) underwent renal ultrasound. Parenchymal thickness, length, transverse diameter and antero-posterior diameter were measured. Mean renal parenchymal thickness was significantly lower in LBW infants than in NBW infants. Renal parenchymal thickness was closely correlated with an increase in renal volume (r = 0.76, p < 0.0001). Renal parenchymal thickness is a single measurement that could potentially be a more useful and accurate approach to monitoring renal growth in growth-restricted infants than renal volume.

Excessive urinary tract dilatation and proteinuria in pregnancy: a common and overlooked association?

BACKGROUND

Proteinuria and dilatation of the urinary tract are both relatively common in pregnancy, the latter with a spectrum of symptoms, from none to severe pain and infection. Proteinuria is a rare occurrence in acute obstructive nephropathy; it has been reported in pregnancy, where it may pose a challenging differential diagnosis with pre-eclampsia.The aim of the present study is to report on the incidence of proteinuria (≥ 0.3; ≥ 0.5 g/day) in association with symptomatic-severe urinary tract dilatation in pregnancy.

METHODS

Case series.

SETTING

Nephrological-Obstetric Unit dedicated to pregnancy and kidney diseases (January 2000-April 2011).

SOURCE

database prospectively updated since the start of the Unit. Retrospective review of clinical charts identified as relevant on the database, by a nephrologist and an obstetrician.

RESULTS

From January 2000 to April 2011, 262 pregnancies were referred. Urinary tract dilatation with or without infection was the main cause of referral in 26 cases (predominantly monolateral in 19 cases): 23 singletons, 1 lost to follow-up, 1 twin and 1 triplet. Patients were referred for urinary tract infection (15 cases) and/or renal pain (10 cases); 6 patients were treated by urologic interventions ("JJ" stenting). Among them, 11 singletons and 1 triple pregnancy developed proteinuria ≥ 0.3 g/day (46.1%). Proteinuria was ≥ 0.5 g/day in 6 singletons (23.1%). Proteinuria resolved after delivery in all cases. No patient developed hypertension; in none was an alternative cause of proteinuria evident. No significant demographic difference was observed in patients with renal dilatation who developed proteinuria versus those who did not. An association with the presence of "JJ" stenting was present (5/6 cases with proteinuria ≥ 0.5 g/day), which may reflect both severer obstruction and a role for vescico-ureteral reflux, induced by the stent.

CONCLUSIONS

Symptomatic urinary tract dilatation may be associated with proteinuria in pregnancy. This association should be kept in mind in the differential diagnosis with other causes of proteinuria in pregnancy, including pre-eclampsia.

Unilateral anomalies of kidney development: why is left not right?

Abnormal renal development results in congenital anomalies of the kidney and urinary tract. As many studies suggest that renal malformations are more often found on the left side, a meta-analysis was performed on the distribution of five different unilateral anomalies: multicystic dysplastic kidney, renal agenesis/aplasia, renal ectopia, pelviureteral junction obstruction, and non-obstructive non-refluxing megaureter. Of these anomalies, the left side was affected in 53%, 57%, 56.9%, 63.2%, and 62.5% of patients, respectively, significantly different when compared with an anticipated 50% of left-sided anomalies. An exception to this left-side predominance was found in females with combined genital anomalies and unilateral renal agenesis that commonly present on the right side. The exact mechanisms leading to these lateralizations remain to be determined but may involve vascular development, differential gene expression, or susceptibility to environmental factors such as hypoxia. This remains largely speculative, however, illustrating our limited knowledge of embryogenesis in general and nephrogenesis in particular.