Pre- and post-treatment urinary tract findings in children with nephrogenic diabetes insipidus

The natural history of untreated X-linked nephrogenic diabetes insipidus with mutation in the vasopressin V2 receptor gene

Nephrogenic diabetes insipidus (NDI) results from the kidneys' inability to concentrate urine. We describe a 6-month-old male with a history of poor weight gain who presented with an incidental finding of hypernatremia (155 mEq/L) during an episode of acute gastroenteritis. The arginine vasopressin (AVP) test, along with molecular analysis revealing the M272R mutation in the AVP receptor 2 (AVPR2) gene, confirmed the diagnosis of congenital NDI. Interestingly, this mutation was also identified in the patient's maternal grandfather, who had never been diagnosed or treated for NDI despite a history of polydipsia, polyuria, and evidence of chronic kidney disease (CKD), severe bilateral hydronephrosis, hypertension, and severe bladder dysfunction. Early intervention with hydrochlorothiazide in the infant resulted in a significant reduction in urinary output and improved growth. The untreated grandfather's case highlights the potential severity of untreated NDI and the benefits of timely therapeutic intervention. This report contributes to the limited long-term data on congenital NDI, emphasizing the critical role of early detection and consistent management in preventing severe complications such as CKD, hydronephrosis, and bladder dysfunction. Regular follow-up, including renal ultrasound and monitoring of renal function, is essential for effectively managing NDI and improving patient outcomes.

Diagnosing a genetic disease in a donor-conceived child: case report and discussion of the ethical, legal, and practical issues

We describe the unexpected challenges pediatricians may experience when children conceived with assisted reproduction are diagnosed with a rare genetic condition. A local case series triggered a dialogue between many stakeholders with varied expertise. Indeed, diagnosing a genetic disease in a child conceived by embryo, egg, or sperm donation is becoming more common now that genetic testing and in vitro fertilization (IVF) are readily accessible. However, how and whether to share that information with other stakeholders in the gamete donation process has not been fully explored, and the clinical responsibilities of the treating clinician remain ill-defined. This work centers on a patient with a confirmed diagnosis of X-linked nephrogenic diabetes insipidus. Ultimately, we found the same AVPR2 mutation in two children from two families conceived by egg donation. It led to multigenerational cascade diagnoses in the family of the shared, anonymous egg donor. First, we review current genetic testing practices in gamete donation and third-party reproduction. Then, we provide an overview of relevant genomic, ethical, legal, and psychosocial considerations for sharing relevant genomic information. Finally, and to maximize the best interests of genetic relatives, we discuss how a pediatrician can play a role in the early disclosure of relevant clinical information to all stakeholders in the gamete donation process, starting with the fertility clinic. While these clinical cases are cast in a Canadian context, we submit that its important lessons generally apply to medical systems of nearly all developed countries, broadly defined.

Upper urinary dilatation and treatment of 26 patients with diabetes insipidus: A single-center retrospective study

OBJECTIVE

To describe the urinary tract characteristics of diabetes insipidus (DI) patients with upper urinary tract dilatation (UUTD) using the video-urodynamic recordings (VUDS), UUTD and all urinary tract dysfunction (AUTD) systems, and to summarize the experience in the treatment of DI with UUTD.

METHODS

This retrospective study analyzed clinical data from 26 patients with DI, including micturition diary, water deprivation tests, imaging data and management. The UUTD and AUTD systems were used to evaluate the urinary tract characteristics. All patients were required to undergo VUDS, neurophysiologic tests to confirm the presence of neurogenic bladder (NB).

RESULTS

VUDS showed that the mean values for bladder capacity and bladder compliance were 575.0 ± 135.1 ml and 51.5 ± 33.6 cmH₂O in DI patients, and 42.3% (11/26) had a post-void residual >100 ml. NB was present in 6 (23.1%) of 26 DI patients with UUTD, and enterocystoplasty was recommended for two patients with poor bladder capacity, compliance and renal impairment. For the 24 remaining patients, medication combined with individualized and appropriate bladder management, including intermittent catheterization, indwelling catheter and regular voiding, achieved satisfactory results. High serum creatinine decreased from 248.0 ± 115.8 μmoI/L to 177.4 ± 92.8 μmoI/L in 12 patients from a population with a median of 108.1 μmoI/L (IQR: 79.9-206.5 μmoI/L). Forty-four dilated ureters showed significant improvement in the UUTD grade, and the median grade of 52 UUTD ureters decreased from 3 to 2.

CONCLUSION

Bladder distension, trabeculation and decreased or absent sensations were common features for DI patients with UUTD. Individualized therapy by medication combined with appropriate bladder management can improve UUTD and renal function in DI patients.

Nephrogenic diabetes insipidus in children (Review)

Nephrogenic diabetes insipidus (NDI) is characterized by impaired urinary concentrating ability, despite normal or elevated plasma concentrations of the antidiuretic hormone, arginine vasopressin (AVP). NDI can be inherited or acquired. NDI can result from genetic abnormalities, such as mutations in the vasopressin V2 receptor (AVPR2) or the aquaporin-2 (AQP2) water channel, or acquired causes, such as chronic lithium therapy. Congenital NDI is a rare condition. Mutations in AVPR2 are responsible for approximately 90% of patients with congenital NDI, and they have an X-linked pattern of inheritance. In approximately 10% of patients, congenital NDI has an autosomal recessive or dominant pattern of inheritance with mutations in the AQP2 gene. In 2% of cases, the genetic cause is unknown. The main symptoms at presentation include growth retardation, vomiting or feeding concerns, polyuria plus polydipsia, and dehydration. Without treatment, most patients fail to grow normally, and present with associated constipation, urological complication, megacystis, trabeculated bladder, hydroureter, hydronephrosis, and mental retardation. Treatment of NDI consist of sufficient water intake, low-sodium diet, diuretic thiazide, sometimes in combination with a cyclooxygenase (COX) inhibitor (indomethacin) or nonsteroidal anti-inflammatory drugs (NSAIDs), or hydrochlorothiazide in combination with amiloride. Some authors note a generally favorable long-term outcome and an apparent loss of efficacy of medical treatment during school age.

Identification of a Novel Arginine Vasopressin Receptor 2 Mutation (p.V183M) in a Chinese Family with Nephrogenic Diabetes Insipidus

Loss of function of arginine vasopressin receptor 2 (AVPR2) may affect the recognition and binding of arginine vasopressin (AVP) which, in turn, may prevent the activation of Gs/adenylate cyclase and reduce the reabsorption of water by renal tubules and combined tubes. Finally, the organism may suffer from nephrogenic diabetes insipidus (NDI), a kind of kidney disorder featured by polyuria and polydipsia, due to a break of water homeostasis. In this study, we enrolled a Chinese family with polyuria and polydipsia. The proband presented abnormal fluid intake and excessive urine output. A water deprivation and AVP stimulation test further indicated that this patient had NDI. By sequencing known causative genes for diabetes insipidus, we identified a novel mutation in AVPR2 (c.547G>A; p.V183M) in the family. This mutation, located in a conserved site of AVPR2 and predicted to be disease-causing by informatics programs, was absent in our 200 controls and other public databases. Our study not only further confirms the clinical diagnosis, but also expands the spectrum of AVPR2 mutations and contributes to genetic diagnosis and counseling of patients with NDI.

Life with one kidney

Life with a solitary functioning kidney (SFK) may be different from that when born with two kidneys. Based on the hyperfiltration hypothesis, a SFK may lead to glomerular damage with hypertension, albuminuria and progression towards end-stage renal disease. As the prognosis of kidney donors was considered to be very good, having a SFK has been considered to be a benign condition. In contrast, our research group has demonstrated that being born with or acquiring a SFK in childhood results in renal injury before adulthood in over 50% of those affected. Most congenital cases will be detected during antenatal ultrasound screening, but up to 38% of cases of unilateral renal agenesis are missed. In about 25-50% of cases of antenatally detected SFK there will be signs of hypertrophy, which could indicate additional nephron formation and is associated with a somewhat reduced risk of renal injury. Additional renal and extrarenal anomalies are frequently detected and may denote a genetic cause for the SFK, even though for the majority of cases no explanation can (yet) be found. The ongoing glomerular hyperfiltration results in renal injury, for which early markers are lacking. Individuals with SFK should avoid obesity and excessive salt intake to limit additional hyperfiltration. As conditions like hypertension, albuminuria and a mildly reduced glomerular filtration rate generally do not result in specific complaints but may pose a threat to long-term health, screening for renal injury in any individual with a SFK would appear to be imperative, starting from infancy. With early treatment, secondary consequences may be diminished, thereby providing the optimal life for anyone born with a SFK.