Normal liver stiffness and its determinants in healthy blood donors

Several studies in healthy populations have investigated normal liver stiffness on transient elastography, but none has excluded subjects with fatty liver.

To define normal liver stiffness and its determinants in 923 healthy voluntary blood donors with and without fatty liver.

Seven hundred and forty six subjects were analyzed with transient elastography according to the absence (602) or presence of fatty liver (144) at ultrasonography. The cut-off for significant fibrosis was a liver stiffness of 7.9kPa.

Normal subjects had significantly lower liver stiffness (median 4.4kPa) than fatty liver subjects (median 5.3, p<0.001). In normal livers male gender was significantly associated with increased liver stiffness at multiple linear regression analysis. Nine (1.4%) blood donors with normal liver and 9 with fatty liver (6.2%) had >7.9kPa. Subjects with verified liver stiffness >7.9kPa, were further investigated with liver biopsy or non-invasive fibrosis markers: only 1 patient with fatty liver had >F1 fibrosis.

Liver stiffness in normal liver is lower than in fatty liver, and gender is the only influencing variable. Transient elastography has a very low false positive rate for significant fibrosis and may have a role in screening populations at risk for liver disease.