多种微量元素联合使用不应一刀切！
2010-03-12 20:17:58   来源：丁香园   作者：  评论：0 点击：

60%长期家庭营养患者微量元素水平异常提示治疗需个体化
　　目的：最近几年为TPN患者提供适量的微量营养素，特别是微量元素（TE）越来越受到关注。使用足量的多种微量元素（MTE）联合制剂已受到质疑，长期PN患者最常见的是锰及其潜在的神经毒性。由于血浆或血清水平不能真实地反映体内实际储备量，很难正确评估TE水平。这些试验标本采集需要经过特殊处理以确保结果的准确性。这些方案在医院以外很难实施。TE水平也可由于感染或急性期反应出现偏差。所有这些变量使每日依靠TE输注的HPN患者受到重要关注。

　　方法：2008年至2009年期间入选69例HPN患者总计120次血样进行微量元素检验。10个不同地区的患者接受HPN时间从5个月至24年不等。根据不同实验室需求测定血清锌、硒、铜、铬及血锰水平。收集异常结果，包括不同实验室的正常值范围。同时记录了检验后个体TE需求量。

　　结果：使用6个月PN后，和/或随后6个月或每年例行的常规血液检测发现61%的患者微量元素水平异常，他们需要个体化微量元素。120份标本中，35%的标本锰升高，28%的标本铬升高。14%的标本铜升高，18%的标本锌降低。10%的标本硒水平低于正常水平。

　　结论：该HPN人群TE水平快速检测结果支持改变当前可用MTE制剂的论点。异常水平微量元素检出比率很高，尤其是锰和铬，提示我们的实践标准应该更改，推荐使用PN后每3个月而非6个月检测一次微量元素水平。由于许多机构不熟悉正确的流程，现在已制成了一种新的微量元素测试盒，包括特殊的采血试管，无菌手套等。PN患者如何正确评估微量元素情况以及确保补充足够的微量元素仍具有挑战。个体化剂量和早期监测是解决当前存在的影响结果的众多因素的唯一方法。更加精确的测量方法以及改良的MTE产品线，或者清除锰元素，也许能够帮助临床医生更加简单地满足HPN患者需求，同时避免神经毒性风险。

Clinical Nutrition Week 2010 Nutrition Practice Abstracts

Abstracts of Distinction

Nutr Clin Pract. 2010 Feb;25(1):98.

P10 - Multi-Trace Element Combinations: One Size Does Not Fit All! Abnormal Levels Drive Need for Individualization in 60% of Longer Term HPN Patients

Penny L. Allen, RD, LD, CNSC; Barbara Corey, RD, LDN, CNSC; Jana Wayne, RD, CD, CNSC; Roberta Hurley, Ph.D, RD, LD; Karen Ackerman, RD, MS, LDN, CNSD; Kara Helzer, RD, LD, CNSD; Cindi Rafoth, RD, LD; Susan Mandel, MS, RD; Nancy L. Sceery, RD, LDN, CNSD

Nutrition Support, Critical Care Systems, Nashua, NH.

Introduction: The challenge of providing appropriate doses of micro-nutrients, particularly trace elements (TE) for TPN patients has received more attention in the last few years. The adequacy of multi-trace element (MTE) combinations has been called into question, most frequently with manganese and the potential for neurotoxicity in longer term PN patients. It is difficult to accurately assess TE status since plasma or serum levels often do not reflect actual body stores. Often the specimen collection for these tests require special handling in order to insure integrity of the results. These protocols can prove especially challenging outside of the hospital or clinic setting. TE levels can also be skewed by infection and acute phase responses. All of these variables raise significant concerns for the HPN patient reliant on daily TE infusions. Methods: Trace element assays were reviewed for 69 HPN patients with a total of 120 blood draws between 2008-2009. Length of stay on HPN ranged from 5 months to 24 years with patients residing in 10 different geographic markets. Serum zinc, selenium, copper, chromium and whole blood manganese levels were drawn according to individual lab requirements. Abnormal results were collected retrospectively by branch via medical records including lab reports specifying normal ranges for individual laboratories. Need for individualized TE dosing after the draw was also documented. Results: Sixty one (61) percent of patients required individualization of trace elements after abnormal levels were detected in a routine blood draw after 6 months on PN, and/or subsequent 6 month or yearly intervals. Of the 120 individual draws, manganese was elevated in 35% of the assays, followed by chromium elevated at 28%. Zinc was below normal 18% of the time followed by copper elevated 14% of the draws. Selenium followed with lower than normal levels in 10% of the panels. Conclusions: This retrospective snapshot of TE levels in a HPN population supports the argument for reformulation of the MTE preparations currently available. The high percentage of abnormal levels observed, particularly of manganese and chromium, has prompted a change in our standard of practice, recommending a panel at 3 months rather than 6 months after initiation of PN. A new Trace Element Lab Order Request form was developed with very specific instructions for the blood draw--types of tubes, powder-free gloves, spin down time-frames, etc. since many agencies in the alternate site setting are unfamiliar with correct procedures. It remains a challenge to accurately assess trace element status and assure adequacy of supplementation in the PN patient. Individualization of doses and monitoring earlier appears to be the only solution currently available considering the number of factors possibly affecting results. Better, more accurate assessment methods, as well as a reformulated MTE product line--perhaps eliminating manganese, would allow clinicians to more readily meet the HPN patient's needs without exposing them to risk of neurotoxicity.