"Normal" liver stiffness values differ between men and women: a prospective study for healthy living liver and kidney donors in a native Korean population

Background and Aim: Liver stiffness (LS) measurement can distinguish individuals with potential liver disease (LD) from the general population. However, if LS is sex‐sensitive, prevalence of LD may be incorrectly estimated when the same reference LS value is applied irrespective of sex. Here, we evaluated whether normal ranges of LS differ between healthy men and women. Methods: LS was measured in a cohort of healthy living liver and kidney donors, none of whom suffered from diabetes mellitus, hypertension, hepatitis B or C virus infection, heart or liver dysfunction, or metabolic syndrome. Patients with abnormal laboratory findings related to potential LD (platelet count < 150 × 10³/µL; aspartate aminotransferase > 40 IU/L; alanine aminotransferase ALT] > 40 IU/L; albumin < 3.3 g/dL; total bilirubin > 1.2 mg/dL; gamma‐glutamyl transpeptidase > 54 IU/L; alkaline phosphatase > 115 IU/L) were excluded. Results: Among 242 patients analyzed, the mean age was 34.1 for men (n = 121) and 40.5 years for women (n = 121) (P < 0.001). Men had a higher mean LS value than women (5.2 ± 1.2 vs 4.8 ± 1.1 kPa/P < 0.001). Multivariate‐linear regression analysis identified sex as the only independent factor for LS values (β = 0.361/P = 0.021). Using the 5th–95th percentiles, we determined normal LS ranges of 3.7–7.0 kPa in men and 3.3–6.8 kPa in women. In subgroups with ALT < 30 IU/L (subgroup‐1, n = 216) and ALT < 20 IU/L (subgroup‐2, n = 163), men had significantly higher LS values than women (5.2 ± 1.3 vs 4.7 ± 1.1 kPa/P = 0.003 and 5.1 ± 1.2 vs 4.7 ± 1.1 kPa/P = 0.030, respectively), demonstrating an independent sex effect (β = 0.483/P = 0.003 and β = 0.389/P = 0.030, respectively). Conclusions: An independent sex effect on LS values was confirmed. Thus, sex‐specific references should be used for effective screening based on LS measurements.