[Calcium and phosphorus homeostasis of hypotrophic newborn infants fed breast milk]

Area of Science:

• Neonatalogy
• Pediatric Nephrology
• Biochemistry

Background:

• Infants small for gestational age (SGA) may experience intrauterine growth restriction, potentially impacting mineral metabolism.
• Monitoring calcium and phosphorus homeostasis is crucial for low birth weight infants (LBWI).

Purpose of the Study:

• To investigate serum and renal calcium and phosphorus levels in SGA infants compared to appropriate for gestational age (AGA) controls.
• To determine the optimal monitoring strategy for calcium-phosphorus homeostasis in the early neonatal period.

Main Methods:

• Prospective randomized study comparing 26 SGA LBWI with control groups of very low birth weight infants (VLBWI) and LBWI appropriate for gestational age (AGA).
• Measurement of serum calcium, phosphorus, and alkaline phosphatase activity.
• Assessment of renal calcium and phosphorus excretion in a subset of SGA infants.

Main Results:

• SGA infants showed a trend towards lower serum phosphorus and higher alkaline phosphatase, but values were within normal ranges and not statistically significant.
• Significantly lower renal phosphorus excretion and higher renal calcium excretion were observed in SGA infants compared to controls, evident even on day 3 of life.
• Signs of phosphorus deficiency appeared later in VLBWI, AGA infants.

Conclusions:

• Infants born SGA may have insufficient intrauterine phosphorus supply.
• Immediate postnatal phosphorus supplementation is indicated for SGA infants.
• Renal excretion monitoring is more sensitive than serum parameters for assessing calcium-phosphorus balance in early neonatal life.