Novel Algorithm to Estimate Fat-Free Muscle Volumes in Women Using the Urinary Deuterated-Creatine Dilution Method

Area of Science:

• Gerontology
• Biomedical Engineering
• Nutritional Science

Background:

• Muscle mass loss after menopause is linked to frailty and poor physical function in aging women.
• The deuterated creatine (D3Cr) dilution method assesses muscle mass but requires validation in Asian populations.
• Magnetic resonance imaging (MRI) serves as the reference standard for muscle mass measurement.

Purpose of the Study:

• To develop and validate a novel D3Cr algorithm (D3CrHt-Wt) for estimating fat-free muscle mass in Asian women.
• To incorporate anthropometric variables into the D3Cr method to improve accuracy.
• To compare the performance of the new algorithm against existing D3Cr methods and MRI.

Main Methods:

• Recruited 451 women (aged 45-69) from the Integrated Women's Health Programme (IWHP).
• Administered 30 mg of D3Cr and collected urine samples for analysis of creatine and D3-creatinine levels.
• Developed the D3CrHt-Wt algorithm using stepwise multivariable regression, incorporating D3Cr-determined creatine pool size, body weight, and height.
• Validated the D3CrHt-Wt algorithm against MRI measurements of fat-free thigh and erector spinae volumes.

Main Results:

• The D3CrHt-Wt algorithm demonstrated a high correlation (R=0.813) with MRI-measured fat-free muscle volumes in the validation cohort.
• The new algorithm outperformed existing methods (D3Cr_original R=0.672, D3Cr_modified R=0.692).
• Bland-Altman analysis showed low bias (-0.112 L) and acceptable limits of agreement (-0.969 L to +1.190 L) between D3CrHt-Wt and MRI.

Conclusions:

• The D3CrHt-Wt algorithm provides a highly correlated and agreeable estimation of fat-free muscle volumes compared to MRI.
• The D3Cr method's convenience makes it a promising tool for assessing fat-free muscle mass in sarcopenia studies.
• This validated algorithm can aid in monitoring muscle health and interventions in aging Asian women.