# Etiology and longitudinal kidney outcomes in children with nephrocalcinosis: a retrospective cohort study

## TL;DR

This study examines kidney function decline in children with nephrocalcinosis and identifies factors influencing long-term outcomes.

## Contribution

The study provides new insights into the longitudinal kidney outcomes and prognostic factors in pediatric nephrocalcinosis.

## Key findings

- Median eGFR declined significantly over time in children with nephrocalcinosis.
- Hereditary or genetic causes were associated with lower final eGFR.
- Systemic/syndromic etiology, urinary tract infection history, and older age at diagnosis were linked to greater eGFR decline.

## Abstract

Nephrocalcinosis refers to the deposition of calcium salts within the kidney parenchyma and is a condition encountered in various metabolic, genetic, and systemic disorders in childhood. Nephrocalcinosis is increasingly recognized in children; however, data on long-term kidney outcomes and prognostic factors remain limited.

This study was designed as a retrospective cohort study. We evaluated the clinical characteristics, etiological spectrum, and longitudinal kidney outcomes of children with nephrocalcinosis. Changes in estimated glomerular filtration rate (eGFR) over follow-up were assessed, and factors associated with kidney function decline were analyzed using multivariable regression.

Among 73 children with nephrocalcinosis, 43 were included in longitudinal analyses with a median follow-up of 52 months. Median eGFR declined significantly over time (p = 0.006). Kidney outcomes varied according to underlying etiology, with lower final eGFR observed in children with hereditary or genetic causes. In multivariable analysis, systemic/syndromic etiology, history of urinary tract infection, and older age at diagnosis were independently associated with greater eGFR decline, whereas traditional metabolic risk factors were not independently associated with longitudinal changes in kidney function.

Our findings suggest that pediatric nephrocalcinosis may be associated with a decline in kidney function over long-term follow-up and that kidney outcomes are influenced by underlying etiological and clinical factors. Given the paucity of studies addressing the long-term prognosis of nephrocalcinosis, these results highlight the need for early diagnosis, careful etiological evaluation, individualized risk stratification, and close follow-up, particularly in high-risk subgroups. Furthermore, our study underscores the need for prospective studies to better characterize prognostic factors and optimize long-term care in children with nephrocalcinosis.