Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Centre Mannheim, University of Heidelberg, Germany; Department of Nephrology, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany; Nanfang Hospital, Southern Medical University, Guangzhou, China.
Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology), University Medical Centre Mannheim, University of Heidelberg, Germany; Department of Nephrology, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany.
J Steroid Biochem Mol Biol. 2021 Jun;210:105877. doi: 10.1016/j.jsbmb.2021.105877. Epub 2021 Mar 16.
Measurements of total 25-hydroxyvitamin D (t25(OH)D) are currently primarily used to assess the vitamin D status. The lipophilic cell membrane can only be passed by the un-bound form of 25-hydroxyvitamin D: free 25-hydroxyvitamin D (f25(OH)D). It is thought that f25(OH)D does reflect its biological actions better than t25(OH)D. However, as of today, there are no established guidelines for the clinical use of f25(OH)D. We analysed 5060 patients with simultaneous measurements of free and total 25(OH). Linear regression was used to study the relationship between free 25(OH)D and total 25(OH)D. We reviewed and used the established t25(OH)D reference values and determined the slope of the relationship between them to calculate reference values for f25(OH)D. F25(OH)D and t25(OH)D showed a strong positive linear (r = 0.8395, p < 0.0001) correlation. The slope of the relationship was 0.2833 ± 0.00257. The recommended threshold level of f25(OH)D is 8.499 pg/mL, corresponding to a target concentration for t25(OH)D of at least 30 ng/mL considered as sufficient in most of the international vitamin D guidelines. The upper limit for vitamin D is less clear in the guidelines. Most experts favour an upper limit for t25(OH)D of 100 ng/mL. This is equivalent to 28.330 pg/mL f25OHD. We established based on international guidelines for t25(OH)D reference values for f25(OH)D that are urgently needed for clinical use of f25(OH)D. However, clinical studies with f25(OH)D to confirm our suggestions are needed but will take time.
目前，总 25-羟维生素 D（t25（OH）D）的测量主要用于评估维生素 D 状况。亲脂细胞膜只能通过无结合形式的 25-羟维生素 D 穿过：游离 25-羟维生素 D（f25（OH）D）。人们认为 f25（OH）D 比 t25（OH）D 更能反映其生物学作用。然而，到目前为止，还没有关于 f25（OH）D 临床应用的既定指南。我们分析了 5060 例同时测量游离和总 25（OH）的患者。线性回归用于研究游离 25（OH）D 与总 25（OH）D 之间的关系。我们回顾并使用了既定的 t25（OH）D 参考值，并确定了它们之间关系的斜率，以计算 f25（OH）D 的参考值。f25（OH）D 和 t25（OH）D 显示出强烈的正线性（r = 0.8395，p < 0.0001）相关性。关系的斜率为 0.2833 ± 0.00257。f25（OH）D 的推荐阈值水平为 8.499 pg/mL，相当于大多数国际维生素 D 指南中认为足够的 t25（OH）D 目标浓度至少为 30 ng/mL。维生素 D 的上限在指南中不太明确。大多数专家赞成 t25（OH）D 的上限为 100 ng/mL。这相当于 28.330 pg/mL f25OHD。我们根据国际 t25（OH）D 参考值指南为 f25（OH）D 建立了参考值，这是临床使用 f25（OH）D 急需的。然而，需要进行 f25（OH）D 的临床研究来证实我们的建议，但这需要时间。
