Renal function and kidney length in preterm infants with nephrocalcinosis: a longitudinal study

Area of Science:

• Pediatric Nephrology
• Neonatal Medicine
• Renal Physiology

Background:

• Early life renal injury can predispose to adult hypertension and renal disease.
• Nephrocalcinosis (NC) is a condition observed in preterm infants, potentially impacting kidney development and function.
• Understanding the long-term renal consequences of prematurity-associated NC is critical.

Purpose of the Study:

• To assess renal glomerular and tubular function in preterm infants with NC.
• To measure kidney length (KL) in preterm infants with NC.
• To investigate the association between NC and renal parameters during the first two years of life.

Main Methods:

• Prospective study of 107 preterm infants (63 with NC, 44 controls).
• Kidney function assessed via serum creatinine, eGFR, fractional excretion of electrolytes and uric acid, and urinary analyte to creatinine ratios.
• Kidney length (KL) measured by ultrasonography at multiple time points from 40 weeks postmenstrual age to 24 months.

Main Results:

• The NC group exhibited higher urinary calcium to creatinine ratios (UCa/Ucr), fractional excretion of potassium (FEK), and fractional excretion of uric acid (FEUA) at 3 and 6 months.
• Elevated UCa/Ucr and FEUA persisted at 12 months in the NC group.
• The NC group showed a shorter kidney length (KL) up to 12 months (left) and 24 months (right).

Conclusions:

• Nephrocalcinosis in preterm infants is associated with impaired renal tubular function in the first year of life.
• Preterm infants with NC demonstrate reduced kidney length during early childhood.
• These findings highlight the importance of monitoring renal function and development in preterm infants with NC.