DXA-Based Detection of Low Muscle Mass Using the Total Body Muscularity Assessment Index (TB-MAXI): A New Index with Cutoff Values from the NHANES 1999-2004.

Marco Alessandro Minetto,Maria Giulia Ballatore,Anita Tabacco,Alberto Botter,Chiara Busso,Angelo Pietrobelli

doi:10.3390/jcm11030603

Abstract

The aims of this study were to investigate age-related changes in total body skeletal muscle mass (TBSMM) and the between-limb asymmetry in lean mass in a large sample of adults. Demographic, anthropometric, and DXA-derived data of National Health and Nutrition Examination Survey participants were considered. The sample included 10,014 participants of two ethnic groups (Caucasians and African Americans). The age-related decline of TBSMM absolute values was between 5% and 6% per decade in males and between 4.5% and 5.0% per decade in females. The adjustment of TBSMM for body surface area (TB-MAXI) showed that muscle mass peaked in the second decade and decreased progressively during the subsequent decades. The following thresholds were identified to distinguish between low and normal TB-MAXI: (i) 10.0 kg/m2 and 11.0 kg/m2 in Caucasian and African American females; and (ii) 12.5 kg/m2 and 14.5 kg/m2 in Caucasian and African American males. The lean asymmetry indices were higher for the lower limbs compared with the upper limbs and were higher for males compared with females. In conclusion, the present study proposes the TB-MAXI and lean asymmetry index, which can be used (and included in DXA reports) as clinically relevant markers for muscle amount and lean distribution.

Highlights

Introduction iationsThe assessment of lean mass is crucial for the diagnosis of sarcopenia, which consists of the loss of skeletal muscle mass and function that occurs during the aging process or due to the presence of an underlying disease or medication [1,2,3].Dual-energy X-ray absorptiometry (DXA) is widely adopted in research and clinical settings for the three-compartment model-based assessment of total body lean mass and appendicular lean mass (ALM) [3,4,5,6,7]
The DXA-derived lean indices most commonly included in DXA reports and adopted for the diagnosis of sarcopenia are the absolute values of ALM
This cross-sectional study used the data obtained from the National Health and Nutrition Examination Survey (NHANES) collected from 1999 to 2004

Summary

Introduction

Dual-energy X-ray absorptiometry (DXA) is widely adopted in research and clinical settings for the three-compartment model-based assessment of total body lean mass and appendicular lean mass (ALM) [3,4,5,6,7]. The DXA-derived lean indices most commonly included in DXA reports and adopted for the diagnosis of sarcopenia are the absolute values of ALM and the values of ALM normalized to height squared (to account for allometric differences in body size) to obtain the appendicular lean mass index that enables the comparisons among different subjects independently of their body size [4,5,6,7]. High levels of between-limb asymmetry in lower-extremity lean mass were associated with reduced lower-extremity power [9]

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