313 - Is measuring Skeletal Muscle Mass with the D3-Creatine Dilution Method feasible in Premature Infants?

Poster Number: 313
Publication Number: 313.129

Kathryn Cyrus, Louisiana State University School of Medicine in New Orleans, Metairie, LA, United States; Maggie Jerome, Oregon Health and Science University, Portland, OR, United States; Audrey Reeves, University of Alabama at Birmingham, Birmingham, AL, United States; Kelly Nguyen, UAB, Mobile, AL, United States; Mahalakshmi Shankaran, University of California, Berkeley, Berkeley, CA, United States; William J. Evans, University of California Berkeley, Berkeley, NC, United States; Ariel A.. Salas, University of Alabama School of Medicine, Birmingham, AL, United States

Background: Body composition is emerging as an early indicator of neurodevelopmental and cardiometabolic outcomes in preterm infants. The standard measurement of fat free mass (FFM) via air displacement plethysmography (ADP) includes skeletal muscle mass and other non-skeletal muscle mass (bone, water, and organ tissue), but can only be completed in stable infants not requiring respiratory support. Skeletal muscle mass measured via novel D3-creatine dilution method could be a more specific measure than FFM to define lean body mass and can be measured in unstable preterm infants.

Objective: This study aimed to determine the feasibility of measuring skeletal muscle mass and assess the relationship between skeletal muscle mass and FFM in premature infants.

Design/Methods: We recruited and consented eligible infants born at 28-32 weeks of gestation. Written parental consent was obtained to administer a D-3 creatine supplement enterally and collect a urine sample. At approximately 36 weeks of postmenstrual age (PMA), the urine sample was collected following a one- time administration of D3-creatine. A body composition assessment using air-displacement plethysmography (Peapod®) was also performed around this time.

Results: Of the 94 eligible premature infants that consented for assessment of body composition with the Peapod® , 84 (89%) opted in for additional D3-creatine administration and urine analysis to determine specific skeletal muscle mass. Eleven infants did not receive the supplement as scheduled (13%). Of 73 infants who received the supplement, 67 (92%) had urine samples obtained within an average 21.7 hours after D3-creatine administration. Of 67 infants who received the D3 creatine supplement, 65 completed both the Peapod® assessment and urine collection. FFM percentage with the Peapod® assessments ranged from 69 to 95%. The correlation between FFM and skeletal muscle in kilograms was moderate (r=0.44; p=0.0003).

Conclusion(s): The D3-creatine method of measuring skeletal muscle mass was feasible in preterm infants born at 28-32 weeks of gestation. Barriers to the feasibility of this methodology include parental hesitancy, reliability of relevant medical personnel to correctly administer and collect samples, and timing of the study with relevant clinical scenarios. A modest correlation between skeletal muscle mass and FFM measured using air-displacement plethysmography was observed. The long term associations between skeletal muscle mass, FFM, and long term outcomes warrants further investigation.