# Clinical outcomes among children with primary nephrogenic diabetes insipidus

## TL;DR

Children with primary nephrogenic diabetes insipidus experience growth delays and kidney function changes, highlighting the need for long-term care.

## Contribution

This study provides longitudinal clinical data on growth and kidney function in children with primary nephrogenic diabetes insipidus.

## Key findings

- Height Z-scores declined early but improved after 1.5 years, with final heights below average.
- eGFR increased rapidly until age 1.4, then slowed, with many patients still below normal GFR at 14 years.
- Treatment complications like hypokalemia and hyperuricemia were common among patients.

## Abstract

Primary nephrogenic diabetes insipidus (NDI) is a rare inherited disorder with limited data on long-term outcomes. This study assessed longitudinal outcomes with primary NDI.

This multicenter retrospective study included 63 patients with primary NDI. Growth rates and estimated glomerular filtration (eGFR) were analyzed via a piecewise linear mixed-effects model during the pediatric period.

AVPR2 and AQP2 mutations were identified in 74.6% and 9.5% of patients, respectively. The median ages at diagnosis and last follow up were 0.41 and 12.37 years, respectively. Height Z-scores declined from birth to 1.5 years and improved thereafter, with slopes of −2.626, −0.563, 0.102, and 0.031 per year across breakpoints at 0.5, 1.5, and 7 years. Although none of the patients met the criteria for short stature by age 18, the mean final height Z-score remained below average and was significantly lower than that at birth. Weight and weight-for-height Z-scores initially declined and then improved, with slope changes at 0.5 and 0.7 years. By the age of 18, 38.9% were overweight or obese. eGFR increased rapidly before 1.4 years (slope 25.61 ml/min/1.73 m2/year), and slowly thereafter (slope 0.58), reaching eGFR ≥90 ml/min/1.73 m2 at a median age of 5.1 years. The proportion of patients with eGFR <90 ml/min/1.73 m2 decreased to 34.6% at 14 years, then rose to 43.8% by the age of 18. Treatment-associated complications included hypokalemia (64.5%), alkalosis (61.1%), and hyperuricemia (60.7%).

Patients with primary NDI exhibit a dynamic growth trajectory, delayed achievement of normal GFR with subsequent risk of chronic kidney disease, and frequent treatment-associated complications. These findings underscore the need for timely and individualized long-term management.

Graphical Abstract