Reference Standards for Lean Mass Measures using GE Dual Energy Xray Absorptiometry

Abstract

Body composition (BC) assessments focus predominantly on fat mass, however lean mass (LM) measurements also provide useful information on clinical and nutritional status. LM measurements have been shown to be predictive of health outcomes, including sarcopenia, which has been associated with frailty and reduced quality of life. Dual energy x-ray absorptiometry (DXA) is an established technique used to assess BC, including total and regional LM. Reference values for LM derived from DXA are necessary for interpretation and detection of LM deficits and its associated health issues. Recently reference values for LM measures specific to Hologic DXA systems were developed, however it is known that BC, including LM measures differ by DXA manufacturer. There currently are no LM reference values available for GE-Healthcare DXA systems. PURPOSE:To develop reference values by age and sex for LM measures using with GE-Healthcare DXA systems. METHODS: A de-identified sample, considered exempt from IRB review, was obtained from Ball State University’s Clinical Exercise Physiology Laboratory and University of Wisconsin-Milwaukee’s Physical Activity & Health Research Laboratory. DXA scans of 2,076 women and 1,251 men were completed using a GE Lunar Prodigy or iDXA. Variables of interest included total LM and appendicular lean mass index (ALMI; leg lean mass + arm lean mass (kg)/height (m2)). Percentiles (%ile) were calculated and a factorial ANOVA was used to assess differences for each variable between age groups and sex, as well as the interaction between age and sex. RESULTS: Men had higher mean total LM and ALMI than women (p<0.01), across all age groups. Total LM and ALMI decreased over the 5 decades in men and women (p<0.01). The 50th %ile for total LM of men and women aged 20-29 years decreased from 63.9 and 42.5 kg to 54.2 and 39.1 kg for ages 70-79 years, respectively. The rate of decline in total LM during a 5 decade period was approximately 3% and 2% for men and women per decade, respectively. CONCLUSIONS: These age and sex-specific LM reference values are the first developed specifically for use with GE-Healthcare DXA systems. These reference values provide for a more accurate interpretation of DXA-derived LM measurements providing an initial resource to aid in the early detection and assessment of LM deficits.