Clean intermittent catheterization reverses hydronephrosis in a child with congenital nephrogenic diabetes insipidus:...

Congenital nephrogenic diabetes insipidus (CNDI) is most frequently caused by mutations in the AVPR2 gene. Patients exhibit persistent polyuria due to renal insensitivity to antidiuretic hormone. Chronic high urine output predisposes to bladder dysfunction and upper urinary-tract dilatation, notably hydronephrosis. Although pharmacotherapy can partially reduce urine volume, its capacity to reverse established hydronephrosis is limited. Clean intermittent catheterization (CIC), a mainstay in managing neurogenic bladder, warrants investigation regarding its utility in CNDI-associated hydronephrosis.

A 9-year-old Chinese boy presented with lifelong polydipsia and polyuria, with a peak 24-h urine output of approximately 7100 mL. Renal ultrasonography demonstrated bilateral moderate hydronephrosis. Whole-exome sequencing identified a hemizygous nonsense mutation, AVPR2 c.968G>A (p.Trp323*); his mother was a heterozygous carrier of the same variant. After one month of standard therapy with hydrochlorothiazide and indomethacin, his daily urine volume decreased to approximately 3400 mL/d, but the hydronephrosis showed no improvement. A subsequent video urodynamic study revealed decreased bladder sensation, reduced compliance, and diminished detrusor contractility. In addition to the continued pharmacological regimen, clean intermittent catheterization (performed three times daily at home) was introduced. Follow-up ultrasonography one month later showed significant improvement in the bilateral hydronephrosis.

For pediatric CNDI patients with persistent incomplete bladder emptying and hydronephrosis despite pharmacotherapy, short-term clean intermittent catheterization can break the vicious cycle of "chronic urinary retention-elevated bladder pressure-upper urinary tract dilatation," representing a safe, effective, and readily implementable adjuvant intervention.