Computed Tomography-Derived Skeletal Muscle Radiodensity Is an Early, Sensitive Marker of Age-Related Musculoskeletal Changes in Healthy Adults

Yeon Woo Jung, Namki Hong, Joon Chae Na, Woong Kyu Han, Yumie Rhee

Research output: Contribution to journalArticlepeer-review


Background: A decrease in computed tomography (CT)-derived skeletal muscle radiodensity (SMD) reflects age-related ectopic fat infiltration of muscle, compromising muscle function and metabolism. We investigated the age-related trajectory of SMD and its association with vertebral trabecular bone density in healthy adults. Methods: In a cohort of healthy adult kidney donors aged 19 to 69 years (n=583), skeletal muscle index (SMI, skeletal muscle area/height2), SMD, and visceral-to-subcutaneous fat (V/S) ratio were analyzed at the level of L3 from preoperative CT scans. Low bone mass was defined as an L1 trabecular Hounsfield unit (HU) <160 HU. Results: L3SMD showed constant decline from the second decade (annual change -0.38% and -0.43% in men and women), whereas the decline of L3SMI became evident only after the fourth decade of life (-0.37% and -0.18% in men and women). One HU decline in L3SMD was associated with elevated odds of low bone mass (adjusted odds ratio, 1.07; 95% confidence interval, 1.02 to 1.13; P=0.003), independent of L3SMI, age, sex, and V/S ratio, with better discriminatory ability compared to L3SMI (area under the receiver-operating characteristics curve 0.68 vs. 0.53, P<0.001). L3SMD improved the identification of low bone mass when added to age, sex, V/S ratio, and L3SMI (category-free net reclassification improvement 0.349, P<0.001; integrated discrimination improvement 0.015, P=0.0165). Conclusion: L3SMD can be an early marker for age-related musculoskeletal changes showing linear decline throughout life from the second decade in healthy adults, with potential diagnostic value for individuals with low bone mass.

Original languageEnglish
Pages (from-to)1201-1210
Number of pages10
JournalEndocrinology and Metabolism
Issue number6
Publication statusPublished - 2021 Dec

Bibliographical note

Funding Information:
We thank the SENTINEL (Severance ENdocrinology daTa scIeNcE pLatform) project developed by Sung-Kil Lim Research Award (4-2018-1215) and the 2020 Research fund of the Department of Internal Medicine, Severance Hospital, Seoul, Korea. This work was supported by the Student Research grant of Yonsei University College of Medicine (Yeon Woo Jung, March 2020), faculty research grant of Yonsei University College of Medicine (6-2019-0102; Namki Hong), and the Korean Endocrine Society for New Faculty Convergence Research Award 2019 (Namki Hong). The abstract of this study was presented as poster at annual meeting of American Society for Bone and Mineral Research 2019.

Publisher Copyright:
© 2021 Korean Endocrine Society This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology


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