Renal size and function in patients with neuropathic bladder due to myelomeningocele: the role of growth hormone

The Incidence and Durability of Compensatory Hypertrophy in Pediatric Patients with Solitary Kidneys

OBJECTIVE

To evaluate the incidence and durability of compensatory hypertrophy with solitary kidneys in the setting of those with multicystic dysplastic kidney (MCDK) or Wilms tumor (WT) status postnephrectomy.

PATIENTS AND METHODS

We conducted a retrospective cohort study of patients with MCDK and WT. MCDK patients were verified by sonographic findings prenatally. WT patients entered our study at time of nephrectomy. We compared the natural history of hypertrophy between the 2 cohorts via renal length measurement. We performed linear regression to predict creatinine clearance from renal length after adjusting for age and cohort status (MCDK versus WT).

RESULTS

Fifty-two patients (56%) were diagnosed with WT, and 71 patients (44%) with MCDK patients met study criteria with a median age of postnatal ultrasound at 1.6 months (interquartile range 0.5-3.6). The median (IQR) follow-up time was 7.5 years. At the time of nephrectomy, 25/52 (48%) of Wilms patients had contralateral hypertrophy, while at diagnosis 22/71 (31%) of MCDK patients had contralateral hypertrophy, P = .03. Contralateral hypertrophy was a consistent finding throughout follow-up. As renal length increases by 1 cm, glomerular filtration rate increased by 7.8 mL/min/m² (95% confidence interval 1.8-13.8, P = .01).

CONCLUSION

Contralateral hypertrophy appears to be a compensatory mechanism for unilateral kidney pathology as demonstrated by MCDK and WT patients. Hypertrophy often occurs at the time of diagnosis and appears to be a permanent finding as children reach their teenage years. Additionally, in nonhydronephrotic kidneys, increases in renal length correlate with improvement in glomerular filtration rate. Overall, the majority of children with solitary kidneys demonstrate compensatory hypertrophy.

Small renal size in newborns with spina bifida: possible causes

BACKGROUND

Previous studies reported that children with neural tube defects, but without any history of intrinsic renal diseases, have small kidneys when compared with age-matched standard renal growth. The aim of this study was to investigate the possible causes of small renal size in children with spina bifida by comparing growth hormone deficiency, physical limitations and hyperhomocysteinemia.

METHODS

The sample included 187 newborns with spina bifida. Renal sizes in the patients were assessed by using maximum measurement of renal length and the measurements were compared by using the Sutherland monogram. According to the results, the sample was divided into two groups--a group of 120 patients with small kidneys (under the third percentile) and a control group of 67 newborns with normal kidney size. Plasma total homocysteine was investigated in mothers and in their children. Serum insulin-like growth factor-1 (IGF-1) levels were measured.

RESULTS

Serum IGF-1 levels were normal in both groups. Children and mothers with homocysteine levels >10 μmol/l were more than twice as likely to have small kidneys and to give to birth children with small kidneys, respectively, compared with newborns and mothers with homocysteine levels <10 μmol/l. An inverse correlation was also found between the homocysteine levels of mothers and kidney sizes of children (r = - 0.6109 P ≤ 0.01).

CONCLUSIONS

It is highly important for mothers with hyperhomocysteinemia to be educated about benefits of folate supplementation in order to reduce the risk of small renal size and lower renal function in children.

Ultrasonography and renography to visualize upper urinary tract in children with meningomyelocele - a prospective study

OBJECTIVE

Ultrasonography (US) is commonly used to visualize the upper urinary tract in children and adolescents with meningomyelocele (MMC). The aim of this investigation was to prospectively evaluate US in those with spinal angulation or obesity and compare it to the corresponding results obtained by mercaptoacetyltriglycine renography.

PATIENTS AND METHODS

Twenty-five children and adolescents with MMC and pronounced angulation of the spine or obesity, were prospectively investigated with both US and renography during the period 2006 to 2008.

RESULTS

In 13 (52%) patients the kidneys could not be fully evaluated; in 4 (16%) neither renal size nor pelvic dilation, in 12 (48%) renal length and in 5 (20%) dilation was not accessible. In 23 individuals where dilatation could be evaluated uni- or bilaterally, US was compared to OEE% (%outflow excretion efficiency) at renography. In 1 of these individuals there was normal OEE% while slight dilatation on US was noticed. In 2/15 individuals, split function at renography did not correlate with renal length on US.

CONCLUSION

Severe spinal angulation and obesity in individuals with MMC reduced the possibility to evaluate the urinary tract by US. However, it seems that renography could be a reliable alternative to evaluate renal condition in those patients where US is insufficient.

Renal function in children with congenital neurogenic bladder

AIMS

Preservation of renal function in children with congenital neurogenic bladder is an important goal of treatment for the disease. This study analyzed the evolution of renal function in patients with congenital neurogenic bladder.

METHODS

We reviewed the records of 58 pediatric patients with respect to the following attributes: gender, age, etiology of neurogenic bladder, reason for referral, medical/surgical management, episodes of treated urinary tract infections, urodynamics, DMSA scintigraphy, weight, height, blood pressure, glomerular filtration rate, microalbuminuria and metabolic acidosis. Statistical analysis was performed, adopting the 5% significance level.

RESULTS

The mean age at presentation was 4.2 ± 3.5 years. Myelomeningocele was the most frequent etiology (71.4%). Recurrent urinary tract infection was the reason for referral in 82.8% of the patients. Recurrent urinary tract infections were diagnosed in 84.5% of the patients initially; 83.7% of those patients experienced improvement during follow-up. The initial mean glomerular filtration rate was 146.7 ± 70.1 mL/1.73 m²/min, and the final mean was 193.6 ± 93.6 mL/1.73 m²/min, p = 0.0004. Microalbuminuria was diagnosed in 54.1% of the patients initially and in 69% in the final evaluation. Metabolic acidosis was present in 19% of the patients initially and in 32.8% in the final assessment.

CONCLUSIONS

Patient referral to a pediatric nephrologist was late. A reduction in the number of urinary tract infections was observed with adequate treatment, but microalbuminuria and metabolic acidosis occurred frequently despite adequate management.

[Follow-up of adult patients with myelomeningocele]

The adult outcome of spina bifida patients is fraught with multiple problems reflecting the multisystemic nature of the disease. These problems result in both mortality, actually caused in most cases by the shunt, and morbidity, mostly affecting locomotion and sphincter control. These patients can thus lose ambulation and suffer from worsening incontinence and kidney function. The result in the vast majority of cases is a poor functional and socioprofessional outcome. The patients' demands regarding their occupational and affective lives, as well as procreation, must be heard. This requires a multidisciplinary approach, and pediatric and adult, as well as patient education and financial support for maintaining the patient's autonomy and medical acts allowing the viability of continued medical care.

NFIA haploinsufficiency is associated with a CNS malformation syndrome and urinary tract defects

Complex central nervous system (CNS) malformations frequently coexist with other developmental abnormalities, but whether the associated defects share a common genetic basis is often unclear. We describe five individuals who share phenotypically related CNS malformations and in some cases urinary tract defects, and also haploinsufficiency for the NFIA transcription factor gene due to chromosomal translocation or deletion. Two individuals have balanced translocations that disrupt NFIA. A third individual and two half-siblings in an unrelated family have interstitial microdeletions that include NFIA. All five individuals exhibit similar CNS malformations consisting of a thin, hypoplastic, or absent corpus callosum, and hydrocephalus or ventriculomegaly. The majority of these individuals also exhibit Chiari type I malformation, tethered spinal cord, and urinary tract defects that include vesicoureteral reflux. Other genes are also broken or deleted in all five individuals, and may contribute to the phenotype. However, the only common genetic defect is NFIA haploinsufficiency. In addition, previous analyses of Nfia^−/− knockout mice indicate that Nfia deficiency also results in hydrocephalus and agenesis of the corpus callosum. Further investigation of the mouse Nfia^+/− and Nfia^−/− phenotypes now reveals that, at reduced penetrance, Nfia is also required in a dosage-sensitive manner for ureteral and renal development. Nfia is expressed in the developing ureter and metanephric mesenchyme, and Nfia^+/− and Nfia^−/− mice exhibit abnormalities of the ureteropelvic and ureterovesical junctions, as well as bifid and megaureter. Collectively, the mouse Nfia mutant phenotype and the common features among these five human cases indicate that NFIA haploinsufficiency contributes to a novel human CNS malformation syndrome that can also include ureteral and renal defects.

Central nervous system (CNS) and urinary tract abnormalities are common human malformations, but their variability and genetic complexity make it difficult to identify the responsible genes. Analysis of human chromosomal abnormalities associated with such disorders offers one approach to this problem. In five individuals described herein, a novel human syndrome that involves both CNS and urinary tract defects is associated with chromosomal disruption or deletion of NFIA, encoding a member of the Nuclear Factor I (NFI) family of transcription factors. This syndrome includes brain abnormalities (abnormal corpus callosum, hydrocephalus, ventriculomegaly, and Chiari type I malformation), spinal abnormalities (tethered spinal cord), and urinary tract abnormalities (vesicoureteral reflux). Nfia disruption in mice was already known to cause hydrocephalus and abnormal corpus callosum, and is now shown to exhibit renal defects and disturbed ureteral development. Other genes besides NFIA are also disrupted or deleted and may contribute to the observed phenotype. However, loss of one copy of NFIA is the only genetic defect common to all five patients. The authors thus provide evidence that genetic loss of NFIA contributes to a distinct CNS malformation syndrome with urinary tract defects of variable penetrance.

The effect of malnutrition on kidney size in children

Malnutrition is a widespread disorder in children, and ultrasonography is the method of choice to estimate kidney dimensions. Previously, kidney sizes had been studied in healthy newborns and in pediatric patients; however, kidney sizes were not investigated sufficiently in malnourished children. The study group consisted of 74 children with energy malnutrition (marasmus), and the control group consisted of 47 healthy children. Kidney sizes were mesaured by the same radiologist using ultrasonography. The mean age of the marasmic group was 29.6 +/- 14.0 months. Malnourished children had significantly lower kidney length and renal volume but higher relative kidney volume (cm3/body weight) compared with controls (P < 0.05). The mean length and volume of left kidney were higher than those of right kidney in both marasmic and control groups (P < 0.05). The strongest positive correlations were found between body height and kidney length, depth and volume in marasmic group. Regression analysis revealed that height and age of marasmic children had a significant effect on kidney volume; however, only body height had an effect on kidney length. In conclusion, malnourished children had smaller kidney sizes, and body height was the main determinant of their kidney length and volume. The potential long-term detrimental consequences of poor renal growth in malnutrition need to be investigated.

Ultrasonography to visualize the upper urinary tract in children with meningomyelocele

OBJECTIVE

To evaluate the frequency of difficulties when using ultrasonography (US, commonly used to visualize the upper urinary tract) to evaluate renal length and dilatation in children and adolescents with meningomyelocele (MMC), who have excessive obesity or a distorted spine.

PATIENTS AND METHODS

The records of all children with MMC investigated during 1996-2002 were assessed retrospectively and the last investigation used for analysis. In addition to the US results, the body mass index (BMI) and angulation of the spine were recorded.

RESULTS

Of the 160 children investigated, US was not evaluable in 46 (29%), i.e. in 35 (22%) for renal length, in one (1%) for dilatation and in 10 (6%) for both. In 99 patients with a straight spine and mild to moderate angulation, renal length was not measurable in 14 (14%), while dilatation was not evaluable in two (2%). In 61 patients with a severely angled spine, the corresponding values were 31 (51%) and nine (15%), respectively. In eight patients with a BMI of >or= 27 kg/m2 and a straight spine, four of the investigations were not completely evaluable, while six were not in the eight patients with both a BMI of >or= 27 kg/m2 and severe angulation.

CONCLUSION

Both severe spinal angulation and a BMI of >or= 27 kg/m2 significantly reduced the possibility of evaluating the urinary tract by US. However, in an unselected group of children with MMC, dilatation could be evaluated in >90% and renal length in approximately 70%.