Association of serum gamma-glutamyl transferase with myosteatosis assessed by muscle quality mapping using abdominal computed tomography

Purpose: Myosteatosis, which is associated with a variety of cardiometabolic illnesses, represents muscle quality, an important aspect of sarcopenia. A new laboratory marker for myosteatosis has been required to more readily identify it. We investigated whether serum gamma-glutamyl transferase (GGT) levels are associated with myosteatosis measured by computed tomography (CT). Methods: The total abdominal muscle area (TAMA) of 13,452 subjects was measured at the L3 level with abdominal CT. TAMA was segmented into intramuscular adipose tissue and skeletal muscle area (SMA), which was further classified into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). The following variables were adopted as indicators of myosteatosis: SMA/body mass index (BMI), NAMA/BMI, LAMA/BMI, and NAMA/TAMA. Logistic regression analysis was used to examine the odds ratio (OR) of each GGT quartile for the highest quartile of myosteatosis indices in each sex. Results: The mean age and serum GGT levels were 53.7 years and 32.8 IU/L (standard deviation [SD], 37.6), respectively, in men, and 53.2 years and 18.4 IU/L (SD, 19.8) in women. In both sexes, the ORs of all myosteatosis indices differed significantly between GGT quartiles. Indices of good- and poor-quality muscle were negatively and positively correlated with GGT levels, respectively. Conclusion: Higher GGT levels were significantly associated with advanced myosteatosis defined by reliable CT indices. This result opens the possibility for using GGT as a cost-effective indicator of myosteatosis. Further prospective research on changes to GGT levels with myosteatosis alleviation will validate GGT as a monitoring marker.