Search

The burden of liver disease continues to increase in the UK, with liver cirrhosis reported to be the third most common cause of premature death. Iron overload, a condition that impacts liver health, was traditionally associated with genetic disorders such as hereditary haemochromatosis, however, it is now increasingly associated with obesity, type-2 diabetes and non-alcoholic fatty liver disease. The aim of this study was to assess the prevalence of elevated levels of liver iron within the UK Biobank imaging study in a cohort of 9108 individuals. Magnetic resonance imaging (MRI) was undertaken at the UK Biobank imaging centre, acquiring a multi-echo spoiled gradient-echo single-breath-hold MRI sequence from the liver. All images were analysed for liver iron and fat (expressed as proton density fat fraction or PDFF) content using LiverMultiScan. Liver iron was measured in 97.3% of the cohort. The mean liver iron content was 1.32 ± 0.32 mg/g while the median was 1.25 mg/g (min: 0.85 max: 6.44 mg/g). Overall 4.82% of the population were defined as having elevated liver iron, above commonly accepted 1.8 mg/g threshold based on biochemical iron measurements in liver specimens obtained by biopsy. Further analysis using univariate models showed elevated liver iron to be related to male sex (p<10(-16), r2 = 0.008), increasing age (p<10(-16), r2 = 0.013), and red meat intake (p<10(-16), r2 = 0.008). Elevated liver fat (>5.6% PDFF) was associated with a slight increase in prevalence of elevated liver iron (4.4% vs 6.3%, p = 0.0007). This study shows that population studies including measurement of liver iron concentration are feasible, which may in future be used to better inform patient stratification and treatment., Competing Interests: The authors of this manuscript have the following competing interests: Andy McKay, Andrea Dennis, Matt Kelly, Michael Gyngell and Rajarshi Banerjee are employees of a commercial funder: Perspectum Diagnostics. Andy McKay, Andrea Dennis, Matt Kelly, Michael Gyngell, Stefan Neubauer, Rajarshi Banerjee, Henry Wilman are also stockholders of Perspectum Diagnostics. Stefan Neubauer has a paid consultancy with Perspectum Diagnostics, and also holds the position of non-executive director for the company. Jimmy Bell and E. Louise Thomas hold a Knowledge Transfer Partnership award from Innovate UK in collaboration with Perspectum Diagnostics, which funds Henry Wilman’s employment at the University of Westminster. Jimmy Bell and E. Louise Thomas have also received funds for a contract research project from Perspectum Diagnostics to deliver image analysis for a project undertaken by Perspectum Diagnostics. Employment and consultancy of these authors does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: Sex hormones and sex hormone-binding globulin (SHBG) may play a role in fatty liver development. We sought to examine the association of various endogenous sex hormones, including testosterone (T), and SHBG with liver fat using complementary observational and Mendelian randomization (MR) analyses. Methods: The observational analysis included a total of 2,239 participants (mean age 60 years; 35% postmenopausal women) from the population-based KORA study (average follow-up time: 6.5 years). We conducted linear regression analysis to investigate the sex-specific associations of sex hormones and SHBG with liver fat, estimated by fatty liver index (FLI). For MR analyses, we selected genetic variants associated with sex hormones and SHBG and extracted their associations with magnetic resonance imaging measured liver fat from the largest up to date European genome-wide associations studies. Results: In the observational analysis, T, dihydrotestosterone (DHT), progesterone and 17a-hydroxyprogesterone (17-OHP) were inversely associated with FLI in men, with beta estimates ranging from -4.23 to -2.30 [p-value <0.001 to 0.003]. Whereas in women, a positive association of free T with FLI (b = 4.17, 95%CI: 1.35, 6.98) was observed. SHBG was inversely associated with FLI across sexes [men: -3.45 (-5.13, -1.78); women: -9.23 (-12.19, -6.28)]. No causal association was found between genetically determined sex hormones and liver fat, but higher genetically determined SHBG was associated with lower liver fat in women (b = -0.36, 95% CI: -0.61, -0.12). Conclusion: Our results provide suggestive evidence for a causal association between SHBG and liver fat in women, implicating the protective role of SHBG against liver fat accumulation. [ABSTRACT FROM AUTHOR]