Diseases of the digestive system are a well-known and widely recognized factor of the secondary osteoporosis development. A significant contribution to the pathogenesis of bone mineral density (BMD) decrease is made by liver diseases. At the same time, the relationship of non-alcoholic fatty liver disease (NAFLD) with the mechanisms of bone loss and osteoporosis is studied to a far lesser degree.
OBJECTIVE
To assess the quantitative and qualitative characteristics of the bone tissue condition in patients with non-alcoholic fatty liver disease depending on the degree of hepatic parenchyma damage.
MATERIALS AND METHODS
A cross-sectional study included 98 people (54 women and 44 men) with NAFLD diagnosis and liver steatosis confirmed by ultrasonography (US). The mean age of the subjects was 55.2±9.2 years. All patients underwent US of the liver with ultrasonic transient elastography for assessment of the median of the Young’s modulus, dual energy X-ray absorptiometry of the lumbar spine and proximal femur with calculation of trabecular bone score (TBS) was performed. The indices used to determine the degree of hepatic parenchyma damage were calculated: De Ritis ratio and FIB-4. Statistical data processing was performed using the IBM SPSS Statistics software, v. 23.0.
RESULTS
The mean age of examined women was 58.5±8.1 years, men — 51.2±9.1 years (p<0.001 between groups). The diagnostic criteria of liver fibrosis according to the FIB-4 index were met by 20 patients (11 men and 9 women). There were no differences between the FIB-4 index and the median of the Young’s modulus between men and women. The frequency of osteopenia in the examined group amounted to 36.7%, and none of the patients had values corresponding to osteoporosis. Significant intersex differences have been identified only for BMD in the femoral neck. A decrease in TBS has been found in 11.22% of the total number of examined and 30.56% of subjects with reduced BMD. Differences between groups with normal and reduced BMD have been obtained: in men — by age, FIB-4 and albumin-adjusted calcium level, in women — by duration of menopause, FIB-4 and De Ritis ratio. Linear regression analysis in men has shown an independent association of TBS with FIB-4 (β= –0.130; p=0.046) and 25(OH)D level (β= –0.004; p=0.019), in women — BMD in L1—L4 with FIB-4 (β= –0.164; p=0.040). Thus, FIB-4 has been shown to be an independent risk factor of low bone mass in the spine but not in other areas of the skeleton.
CONCLUSION
Reduction of bone mass has been revealed in more than 30% of patients with non-alcoholic fatty liver disease at the stage of liver steatosis. Osteopenia has been found in women more than twice as often compared to men, the most significant differences have been observed in the femoral neck. Despite the lack of statistically significant relationships between liver fibrosis indices and bone tissue condition indicators, FIB-4 was inversely associated with BMD in LI—LIV in women (predominantly in postmenopause) and with TBS in men. Prospective studies should be performed to assess the impact of liver fibrosis progression, disease severity as well as treatment of non-alcoholic fatty liver disease on bone mineral density.
