This Month in Pediatric Urology

Article Outline

• Transforming Growth Factor-β1 Concentrations and Prenatal Asymptomatic Hydronephrosis
• Importance of Methodology on Scintigraphic Image Quality
• Is Age at Toilet Training Associated With Vesicoureteral Reflux or Urinary Tract Infection?
• Copyright

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Transforming Growth Factor-β1 Concentrations and Prenatal Asymptomatic Hydronephrosis 

The decision to recommend surgery for prenatally detected aymptomatic hydronephrosis is based on a variety of factors including degree of hydronephrosis, differential renal function (DRF), drainage curves/patterns and/or change in these parameters over time. Almodhen et al (page 292) from Montreal, Quebec report on the potential diagnostic usefulness of urinary concentrations of transforming growth factor-β1 (TGF-β1) to predict which kidneys are obstructed and will require pyeloplasty. They prospectively studied 42 newborns with unilateral hydronephrosis in a 2-year period. Of the patients 31 were observed (group 1) and the remaining 11 underwent surgery (group 2). Evaluation consisted of urinary levels of TGF-β1 corrected for urinary creatinine, postnatal ultrasound and a standardized diuretic renogram using ^99mtechnetium mercaptoacetyltriglycine. Indications for pyeloplasty were initial ipsilateral DRF less than 35%, an “obstructive” drainage curve with a half-time of greater than 20 minutes, an obstructive washout curve during the diuretic phase, worsening DRF of greater than 5% and worsening drainage curve. Group 1 patients were evaluated during the first 3 months of life, from 3 to 12 months and in year 2 of life. Group 2 patients were evaluated in the first 3 months of life, preoperatively and 3 to 12 postoperatively. The TGF-β1 levels were compared in both groups in the first 3 months of life. Group 1 was observed for a mean duration of 14 months and mean patient age in group 2 at surgery was 6.5 months.

At the 3 evaluation intervals mean ultrasound grade of hydronephrosis decreased significantly from 2.3 to 1.7 to 1.2 and TGF-β1 levels decreased from 11.5 to 8.6 to 6.1 pg/mmol creatinine in group 1. Corresponding values in group 2 were 3.5, 4 and 3, and 23, 29 and 8 pg/mmol creatinine. Mean TGF-β1 levels in the first 3 months of life were 11.5±8 and 23±14 pg/mmol creatinine in groups 1 and 2, respectively (p <0.001). Using a cutoff value of 17 pg/mmol creatinine, TGF-β1 was 82% sensitive and 86% specific in predicting surgery. A significant linear correlation was demonstrated between the initial grade of hydronephrosis and the initial TGF-β1 (correlation coefficient 0, p <0.01). The authors conclude that urinary levels of TGF-β1 changes over time are associated with similar changes in hydronephrosis grade and that these levels in the first 3 months of life may predict the need for surgery in newborns with prenatal hydronephrosis.

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Importance of Methodology on Scintigraphic Image Quality 

Recent investigations have questioned the traditional use of antibiotic prophylaxis for vesicoureteral reflux (VUR) in children. The multicenter National Institutes of Health sponsored RIVUR (Randomized Intervention for Children with VesicoUreteral Reflux) trial is investigating the effectiveness of daily antimicrobial prophylaxis for preventing recurrent tract infection and renal scarring. Ziessman and Majd (page 272) report the results of the imaging RIVUR pilot study of ^99mtechnetium (Tc) dimercaptosuccinic acid (DMSA) scintigraphy. The purpose of the study was to assess imaging quality, demonstrate uniformity and accuracy of interpretation, and facilitate development of a standard protocol for adjudication of image interpretation between core readers. The ^99mTc-DMSA studies were reviewed by 2 experienced nuclear medicine physicians. Abnormalities were classified as acute pyelonephritis or renal scarring, and the number and location of abnormal renal segments (12 per kidney) were noted and graded. Any disagreement was resolved through an adjudication process.

Analysis of the imaging studies revealed variability in image quality and methodology. For parallel hole collimator imaging, the correlation between activity administered and counts was good (r=0.800). For pinhole imaging, the correlation was poor (r=0.110). Adjudication between readers was required in 16 (23%) cases, mostly for errors in data input. Only 4 (6%) studies had differences in interpretation and these were primarily issues of how many and which of the 12 segments were involved, eg segments 9 and 10 vs 8 and 9, or the severity of the defects. Only 2 studies (3%) had different interpretation of normal vs abnormal single segments. In all cases a consensus was achieved.

The authors concluded that inter-observer core reader agreement was high. However, initial methodology and image quality for ^99mTc-DMSA scintigraphy varied more than expected between institutions. Although the majority of images were of good quality, the most common reason for poor image quality was inadequate count acquisition with insufficient attention to the tradeoff between administered dose, length of image acquisition, start time of imaging and resulting image quality. These observations resulted in a more highly standardized protocol for the RIVUR study to ensure good diagnostic quality images, an approach that also has implications for ^99mTc-DMSA studies performed for clinical purposes.

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Is Age at Toilet Training Associated With Vesicoureteral Reflux or Urinary Tract Infection? 

Recent studies have suggested that some infants with VUR may have urodynamic abnormalities which could affect voiding habits. Data regarding voiding patterns are conflicting regarding the association between VUR and dysfunctional elimination. Chen et al (page 268) from Grand Rapids, Michigan analyzed the possible associations between VUR and urinary tract infection (UTI), and the age at toilet training using a database of 1,184 cases including 280 with unilateral VUR, 339 with bilateral VUR, 565 without VUR and 926 with a history of UTIs.

Girls toilet trained earlier than boys by 3 months (p <0.001). There was no gender difference in age at toilet training in regard to unilateral, bilateral or no VUR, or severity of VUR. Although no difference was noted between patients with and without UTI, the timing of the first UTI correlated with the timing of toilet training. For girls who had a UTI at a younger age, the age at toilet training tended to be several months later than other girls, whereas those with a UTI at an older age tended to have been toilet trained earlier (p <0.0001). A similar pattern was noted in boys but was not statistically significant. The authors conclude that children with VUR toilet train at comparable ages as normal children but in those with UTIs, the age at first infection seems to be associated with the age at toilet training.