Estimated skeletal muscle mass and density values measured on computed tomography examinations in over 1000 living kidney donors.

Background/objectives: Currently, there are no widely accepted cut-off points to categorize patients as sarcopenic (low skeletal muscle mass) or myosteatotic based on computed tomography (CT) measurements. Moreover, little is known about skeletal muscle mass in healthy subjects, particularly in a Western-European population.
Subjects/methods: Skeletal muscle mass (skeletal muscle index, cm ² /m ² ) and density (Hounsfield units, HU) at the level of the third lumbar vertebra were measured on contrast-enhanced CT images in live kidney donors with an age range of 18-86 years, who may be considered as healthy subjects, from 2010 to 2015. Differences between sex, body mass index (BMI), age groups, and American Society of Anesthesiologists (ASA) classification were assessed. Mann-Whitney U and Kruskal-Wallis tests were used to compare groups.
Results: Of the 1073 included patients, 499 (46.5%) were male and the median age and BMI were 51 years and 25.4 kg/m ² , respectively. Male gender, increased age, and increased BMI were significantly associated with both skeletal muscle mass and density. Nomograms including these parameters were developed to calculate the estimated skeletal muscle mass and density of a healthy subject and the lower bound of the 90% prediction interval (p5) values were provided.
Conclusions: Skeletal muscle density and mass were significantly associated with sex, age, and BMI in a large cohort of healthy Western-European subjects. The newly developed nomograms may be used to calculate the estimated healthy skeletal muscle mass for individuals in patient populations.