Measuring Growth Quality In Preterm Infants: A Shift Toward Skeletal Muscle Mass

Monitoring growth in preterm infants is crucial but often limited by conventional methods such as fat-free mass (FFM) measurement. A recent study from the University of Alabama at Birmingham proposes a more refined approach—assessing skeletal muscle mass (SMM) using the D₃-creatine (D₃Cr) dilution method as a marker of growth quality.1

The prospective cohort study was conducted between 2020 and 2022. It involved preterm infants born between 28 and 32 weeks of gestation who were clinically stable for detailed evaluation. Researchers compared skeletal muscle mass estimated through the D₃Cr dilution method with FFM measured by air-displacement plethysmography (ADP), a widely accepted noninvasive technique.

Out of 93 infants enrolled, 64 completed all assessments after accounting for consent issues, missing samples, and medical exclusions. The median gestational age of these infants was 30 weeks. The results showed a moderate correlation between skeletal muscle mass and fat-free mass, suggesting that SMM could serve as a more precise indicator of growth quality.

The study also identified several feasibility challenges, including parental hesitancy about dosing, technical difficulties with urine sampling, and logistical hurdles in transporting fragile infants for ADP testing. Despite these barriers, researchers demonstrated that the D₃Cr method can be safely applied in neonatal settings and offers valuable insights into the composition of infant growth.

These findings have meaningful clinical implications. Unlike standard growth metrics focused on overall weight or fat-free mass, measuring skeletal muscle mass could help neonatologists better evaluate tissue development and optimize nutrition and care. As neonatal research advances, tools like the D₃Cr dilution technique may redefine how clinicians assess “healthy growth,” shifting the focus from mere weight gain to the quality of muscle and tissue development critical for long-term health.

Reference:

1. Cyrus KE, Jerome ML, Reeves AV, Nguyen K, Shankaran M, Evans WJ, Salas AA. Correlation Between Skeletal Muscle Mass and Fat-Free Mass in Infants Born Very Preterm. The Journal of Pediatrics. 2025 Jan 1;276:114272.

Link: https://www.sciencedirect.com/science/article/abs/pii/S0022347624003755