Abstract

Background: Hepatic de novo lipogenesis (DNL) is ideally measured in very low-density lipoprotein (VLDL)-triacylglycerol (TAG). In the fasting state, the majority of plasma TAG typically represents VLDL-TAG; however, the merits of measuring DNL in total plasma TAG have not been assessed. This study aimed to assess the performance of DNL measured in VLDL-TAG (DNL_VLDL-TAG) compared to that measured in total plasma TAG (DNL_Plasma-TAG).

Methods: Using deuterated water, newly synthesised palmitate was determined in fasting plasma VLDL-TAG and total TAG in 63 subjects taking part in multiple studies resulting in n = 123 assessments of DNL (%new palmitate of total palmitate). Subjects were split into tertiles to investigate if DNL_Plasma-TAG could correctly classify subjects having ‘high’ (top tertile) and ‘low’ (bottom tertile) DNL. Repeatability was assessed in a subgroup (n = 16) with repeat visits.

Results: DNL_VLDL-TAG was 6.8% (IQR 3.6–10.7%) and DNL_Plasma-TAG was 7.5% (IQR 4.0%−11.0%), and the correlation between the methods was r_s = 0.62 (p < 0.0001). Bland–Altman plots demonstrated similar performance (mean difference 0.81%, p = 0.09); however, the agreement interval was wide (−9.6% to 11.2%). Compared to DNL_VLDL-TAG, 54% of subjects with low DNL were correctly classified, whilst 66% of subjects with high DNL were correctly classified using DNL_Plasma-TAG. Repeatability was acceptable (i.e. not different) at the group level, but the majority of subjects had an intra-individual variability over 25%.

Conclusion: DNL in total plasma TAG performed similarly to DNL in VLDL-TAG at the group level, but there was large variability at the individual level. We suggest that plasma TAG could be useful for comparing DNL between groups.

摘要

背景：肝脏从头脂肪生成 (DNL) 理想地在极低密度脂蛋白 (VLDL)-三酰甘油 (TAG) 中测量。在空腹状态下，大部分血浆TAG通常代表VLDL-TAG；然而，测量总血浆 TAG 中 DNL 的优点尚未得到评估。本研究旨在评估 VLDL-TAG (DNL _VLDL-TAG ) 测量的 DNL 性能与总血浆 TAG (DNL _Plasma-TAG ) 测量的 DNL 性能。

方法：使用氘水测定参与多项研究的 63 名受试者的空腹血浆 VLDL-TAG 和总 TAG 中新合成的棕榈酸酯，得出n  = 123 次 DNL 评估（新棕榈酸酯占总棕榈酸酯的百分比）。将受试者分成三分位数，以调查 DNL _Plasma-TAG是否可以正确对具有“高”（顶部三分位数）和“低”（底部三分位数）DNL 的受试者进行分类。重复性在亚组（n  = 16）中通过重复访视进行评估。

结果： DNL _VLDL-TAG为 6.8% (IQR 3.6–10.7%)，DNL _Plasma-TAG为 7.5% (IQR 4.0%−11.0%)，两种方法之间的相关性为r _s = 0.62 ( p  < 0.0001)。Bland-Altman 图表现出相似的性能（平均差 0.81%，p  = 0.09）；然而，一致区间很宽（-9.6% 至 11.2%）。与 DNL _{VLDL-TAG相比，使用 DNL Plasma-TAG}正确分类了 54% 的低 DNL 受试者，而 66% 的高 DNL 受试者被正确分类。在群体水平上，重复性是可以接受的（即没有差异），但大多数受试者的个体内变异性超过 25%。

结论：在群体水平上，总血浆 TAG 中的 DNL 与 VLDL-TAG 中的 DNL 表现相似，但个体水平上存在较大差异。我们建议血浆 TAG 可用于比较各组之间的 DNL。