When will the Glomerular Filtration Rate in Former Preterm Neonates Catch up with Their Term Peers?

Area of Science:

• Pediatric Nephrology
• Pharmacokinetics
• Growth and Development

Background:

• Glomerular filtration rate (GFR) maturation in preterm infants is not well understood.
• Determining when GFR in preterm infants reaches levels comparable to term infants is crucial for appropriate drug dosing.

Purpose of the Study:

• To develop a comprehensive GFR maturation model for individuals from birth to 18 years of age, encompassing both preterm and term-born infants.
• To apply this GFR model to predict the concentrations of renally excreted drugs in pediatric populations.

Main Methods:

• Combined published inulin clearance and serum creatinine data from preterm and term-born children.
• Developed a GFR model incorporating GFR at birth and an Emax model based on postmenstrual age (PNA).
• Validated the GFR model by applying it to predict concentrations of gentamicin, tobramycin, and vancomycin.

Main Results:

• The GFR model demonstrated that GFR at birth correlates linearly with birth weight.
• Postmenstrual age was the key covariate for GFR maturation, with gestational age influencing PNA50 and current weight influencing GFRmax.
• By age three, GFR in infants born at 26 weeks GA reached 92% of that in infants born at 40 weeks GA.

Conclusions:

• Preterm infants' GFR reaches that of their term-born peers by approximately three years of age.
• Dosage adjustments for renally cleared medications should be considered for preterm infants under three years old.