Normative data for age-specific skeletal muscle area based on computed tomography in Korean population.

Background: Sarcopenia, a progressive loss of muscle mass and function, increases health risks in older adults, especially in rapidly ageing populations like Korea. Computed tomography (CT) imaging at the third lumbar vertebra (L3) level is a gold standard for assessing skeletal muscle area (SMA) and indices (SMIs), yet age- and sex-specific reference values are limited. This multicentre study aimed to establish these values for improved sarcopenia diagnosis.

Methods: We conducted a retrospective study with 2637 healthy Korean adults (1366 men, 1271 women) aged 20 and older, using abdominal CT scans from routine health check-ups at four centres. SMA and SMIs were measured at L3, and T-scores were calculated by comparing participants' values with a healthy young reference group (ages 20-39). Sarcopenia was classified into Classes I and II using standardised cutoffs.

Results: An age-related SMA decline was observed in both sexes, with a more significant reduction in men. Sarcopenia prevalence was higher in men based on the SMA index, while SMA/body mass index (BMI) was more sensitive in women. Class I sarcopenia ranged from 10.1% to 21.3% in men and 10.6% to 23.6% in women, with Class II prevalence between 1.0% and 5.5% in men and 1.3% and 8.3% in women.

Conclusion: This study establishes CT-based reference values for SMA and SMIs, supporting early sarcopenia detection, with the SMA/BMI index proving valuable for both men and women.