【导语】第95届美国内分泌学会年会（ENDO2013）于2013年6月15-18日在美国旧金山隆重举行。大会旨在为内分泌领域研究人员提供最前沿的科学知识与技术，包括基础和临床研究。本次大会参会人数达9300位，创ENDO年会历史新高，共收到摘要约2600份，ENDO2013希望与会者能从中获得有价值的教育内容和发现新的有启发性的想法以促进临床实践。医脉通精选部分会议亮点研究以飨读者！
ENDO2013年会上发表的一项研究显示，青少年的维生素D水平与脉搏波传播速度(PWV)呈负相关，维生素D对青少年的周围血管具有保护作用，低维生素D水平可加速动脉硬化。
用脉搏波传播速度(PWV)测定动脉硬化，是用于成人和儿童的公认的测量血管疾病的标志。动物模型证实维生素D 在血管内皮和平滑肌细胞上有抗炎、抗增殖的作用，进而认为维生素D有保护心脏的作用。在成人中的研究证实血清中25-OH 维生素D 的水平与健康人、肥胖、2型糖尿病患者的脉搏波传播速度(PWV)呈反比关系。这说明低维生素D 水平可作为动脉硬化的一个独立危险因素。到目前为止，尚没有研究探讨青少年的维生素D水平与PWV的关系。
本研究试图在具有高心血管疾病患病风险的肥胖和2型糖尿病青少年患者中，证实低维生素D水平和早期动脉疾病标志物之间的关系。我们假设血清25(OH)D的浓度与动脉硬化呈反向关联，那么，在那些周围血管疾病风险更大的患者中，这种关系更密切存在(2型糖尿病>肥胖>体瘦健康青少年)。
所用研究病例均来自2004年-2010年间在辛辛那提儿童医院开展的一项2型糖尿病青少年患者的心血管疾病研究，对这些患者进行25-OH维生素D水平、甲状旁腺素和肾功能水平检测。研究对象共包括570名青少年(其中，190名糖尿病患者，190名肥胖但无糖尿病者，190名体瘦且无糖尿病、无肥胖者作为对照组)。在研究过程中测定所有研究对象的脉搏波传播速度(PWV)。用方差分析或Kruskal-Wallis 分析来评估整体组平均差的差异。以Spearman相关分析法分析25-OH维生素D水平与PMV的相关性。
结果显示， 研究对象平均年龄为17.9+3.43岁，55%是非洲裔美国人，男性占34%。体瘦、肥胖及2型糖尿病青少年的平均维生素D水平为21.27ng/dl、14.29ng/dl和14.13(p<0.001)。体瘦、肥胖及2型糖尿病青少年的平均脉搏波速度分别为：5.3 m/s、6.29 m/s和6.64m/s。Spearman相关分析证实三组中血清25-OH维生素D水平与动脉硬化呈负相关。相关程度以相关系数r表示，体瘦、肥胖及2型糖尿病青少年的相关系数r分别-0.2616(p<0.001、-0.2706(p<0.001和-0.3607(p< 0.001)。
与成年人相似，青少年的维生素D水平与动脉硬化呈负相关。这种相关性在糖尿病患者中更明显。维生素D对健康、肥胖或2型糖尿病青少年人群的周围血管均具有保护作用。
【研究摘要】
Low Serum Vitamin D Levels Are Associated With Increased Arterial Stiffness in Youth
Pranati Jha*1, Amy Shah2, Phillip Khoury3, Elaine Urbina4, Thomas Kimball5 and Lawrence M Dolan6
1Cincinnati Children's Hosp. Med. Ctr., Cincinnati, OH, 2Cincinnati Childrens Hospital, Cincinnati, OH, 3CCHMC, Cincinnati, OH, 4Cincinnati Children’s Hosp. Med. Ctr., Cincinnati,, OH, 5Cincinnati Children’s Hosp. Med. Ctr., Cincinnati, OH, 6Children's Hosp Med Ctr, Cincinnati, OH
Background:Arterial stiffness, measured as pulse wave velocity (PWV), is an established marker of vascular disease in both adult and pediatric populations (1). Animal models demonstrate that vitamin D has anti-inflammatory and anti-proliferative effects on vascular endothelial and smooth muscle cells. As a result, vitamin D is considered cardioprotective. Studies in adults demonstrate an inverse association between serum levels of 25-OH vitamin D and PWV in healthy (2, 3), obese (4) and type 2 diabetic adults (T2DM) (5) establishing low vitamin D levels as an independent risk factor for arterial stiffness. To date, no studies have explored the association between vitamin D levels and PWV in adolescents and young adults.
Objective:We sought to elicit the association between low vitamin D levels and markers of early arterial disease in a pediatric population that included a high cardiovascular risk group of obese and T2DM youth. We hypothesized that serum 25(OH)D concentrations will be inversely correlated with arterial stiffness and that a stronger relationship will exist in those at greatest risk for peripheral vascular disease (T2DM> obese> lean healthy youth).
Methods:25-OH vitamin D, intact parathyroid hormone and renal profiles were measured in stored samples obtained from The Cardiovascular Disease in Youth with Type 2 Diabetes Study conducted at Cincinnati Children’s Hospital from 2004-2010. The cohort consisted of 570 youth (190 with T2DM, 190 non-diabetic obese controls, and 190 lean, non-diabetic, non-obese controls) who had PWV measured at the time of their study visit. ANOVA or Kruskal–Wallis analyses were used to assess overall group mean differences. Spearman correlations were used to examine the association between 25-OH vitamin D level and PWV.
Results:The mean age of the cohort was 17.9±3.43 years; 55% were African American and 34% were male. The mean vitamin D levels were 21.27 ng/dl in lean youth, 14.29 ng/dl in obese youth and 14.13 ng/dl (p < 0.001) in T2DM youth. The average pulse wave velocity for the groups was: lean, obese and T2DM, 5.30, 6.29 and 6.64 m/s, respectively (p<0.001). Spearman correlations demonstrated that serum 25-OH vitamin D levels were inversely correlated with arterial stiffness for all three groups. The strength of association, measured as the correlation coefficient (r), was -0.2616 (p<0.001) in lean youth, -0.2706 (p<0.001) in obese youth and -0.3607 (p <0.001) in youth with T2DM.
Conclusion: Similar to adult studies, vitamin D levels are inversely associated with arterial stiffness in youth. Additionally, this association appears stronger in the diabetic population. We conclude that vitamin D may play a role in peripheral vascular health in lean, non-diabetic obese and diabetic obese youth.
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