Determinants of transthyretin levels and their association with adverse clinical outcomes among UK Biobank participants.

Transthyretin is a transport protein whose misfolding has been implicated in the development of cardiac amyloidosis. Here, we examine the clinical correlates of transthyretin levels, the differences in transthyretin levels according to the pathogenic V142I TTR variant carrier status, and the association of transthyretin levels with outcomes among 35,206 UK Biobank participants who underwent plasma profiling and were free from prevalent cardiovascular disease and chronic renal disease. Transthyretin levels are lower in females, decrease with increasing C-reactive protein levels, and increase with body mass index, systolic blood pressure, diastolic blood pressure, total cholesterol, albumin levels, triglyceride levels, and creatinine levels. V142I non-carriers [n = 35,167, mean: -0.1 (0.3)] have higher adjusted transthyretin levels compared with the carriers [n = 39, mean: -0.5 (0.3)] (p:<0.001). A standard deviation decrease in transthyretin levels increases the risk of heart failure [HRadj: 1.17 (95% Confidence Interval = 1.08-1.26)] and all-cause mortality [HRadj: 1.18 (95% Confidence Interval = 1.14-1.24)]. This study shows that individuals with low transthyretin levels, such as those carrying the V142I variant, are at a higher risk of heart failure and mortality.