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作者：Norra MacReady  
出處：WebMD醫學新聞

　　【24drs.com】November 6, 2009 (聖地牙哥) — 根據發表於美國腎臟協會(American Society of Nephrology，ASN)2009年會：2009腎臟週的研究發現，透析病患胖一點，可以有較長的生命。
　　
　　在一篇包括8個透析診所、超過600名病患的研究中，體脂肪不到10%者的5年死亡率，是體脂肪20%-29%者的2.5-3倍。根據位於加州Torrance、全美皆有的DaVita連鎖透析診所營養服務全國主任Debbie Benner表示，這些發現認為，體脂肪對於這類病患可能有某種正面效果。
　　
　　體脂肪最高的一組、身體脂肪達40%以上者，存活率最高。
　　
　　Benner小姐解釋，這可以說是一種肥胖的矛盾，越多體脂肪，甚至是肥胖，與透析病患的較佳存活有關。
　　
　　其他研究者在其他重症如癌症和心臟病患者，提出過類似的發現。此一矛盾現象的理由依舊未知，可能的解釋之一是瘦體素(leptin)，一種由脂肪組織分泌的荷爾蒙，有助於增強對於造成心肌梗塞之缺血的免疫反應。越瘦的人，反應越弱。
　　
　　該研究中，研究者在2001至2006年間使用近紅外線分析儀、對8處DaVita診所的671名透析病患測量體脂肪，之後追蹤5年存活率。病患的平均年紀為54歲、52%是男性、54%有糖尿病、30%為非裔美國人。病患根據體脂肪分成5組，從不到10%(n= 34人)到超過40%(n= 89人)；平均體脂肪量為27%。
　　
　　體脂肪最低那一組的5年存活為85%，作為參考組；體脂肪最高的一組，5年存活比參考組延長29%。
　　
　　Benner小姐指出，對於透析病患來說，體重是一個複雜的議題。他們須限制飲食以免增加腎臟負擔，透析治療期間也不可以喝太多液體，這都是為了避免腎臟的過度負擔。不過，本研究的發現認為，太瘦的話也會有風險。
　　
　　田納西州Vanderbilt大學醫學副教授、該大學的透析小組醫療主任、未參與本研究的Talat Ikizler醫師表示，關鍵在於我們必須注意病患吃什麼，聚焦在適當的熱量與蛋白質，並且限制鈉攝取。我認為，需納入考量的是，對這些病患來說，一般人可以嘗試的減重可能並不適當，透析病患的需求和攝食相當不同。
　　
　　Benner小姐和Ikizler醫師皆宣告沒有相關財務關係。
　　
　　美國腎臟協會(ASN)2009年會：2009腎臟週：摘要SA-PO2567。發表於2009年10月31日。

Adiposity Aids Survival in Dialysis Patients

By Norra MacReady
Medscape Medical News

November 6, 2009 (San Diego, California) - Extra body weight could mean a longer life for dialysis patients, according to findings presented here at Renal Week 2009: American Society of Nephrology (ASN) 2009 Annual Meeting.

In a study of more than 600 patients at 8 dialysis clinics, 5-year mortality was 2.5 to 3 times higher among people with less than 10% body fat than among people with 20% to 29% body fat. These findings suggest that adiposity might somehow have a protective effect in this population, said Debbie Benner, MA, RD, national director of nutrition services for the DaVita chain of dialysis clinics across the United States and based in Torrance, California.

The fattest group, with 40% body fat or more, had the highest survival rates.

This is an illustration of the "obesity paradox," in which more body fat, even obesity, is associated with better survival among dialysis patients, Ms. Benner explained.

Other investigators have noted similar findings in patients with other serious illnesses, including cancer and heart disease. The reasons for the paradox remain unknown, although one possible explanation is that leptin, a hormone secreted by fat tissue, contributes to a robust immune response to insults such as ischemia, which lead to myocardial infarction. Skinnier people might have a weaker response.

In this study, the investigators measured the body fat, using near-infrared interactance, of 671 patients undergoing dialysis at 8 DaVita clinics from 2001 to 2006, and then measured 5-year survival. The patients had a mean age of 54 years, 52% were male, 54% were diabetic, and 30% were African American. The patients were divided into quintiles, on the basis of body fat, which ranged from less than 10% (n = 34) to more than 40% (n = 89); average body fat content was 27%.

Five-year survival among people in the lowest quintile was 85% of that of the reference group. Among people in the highest quintile, 5-year survival was 29% longer than that of the reference group.

Weight is a complex issue for dialysis patients, Ms. Benner noted. They require a restricted diet that does not tax their kidneys and are warned not to drink too much fluid between dialysis treatments, also in an effort to prevent an undue burden on their kidneys. However, the findings from this study suggest that being too thin also has its risks.

"The key point is that we need to pay attention to what our patients eat, with a focus on appropriate calories and protein and restricted sodium," said Talat Ikizler, MD, associate professor of medicine at Vanderbilt University in Nashville, Tennessee, and medical director of the university's dialysis unit. Dr. Ikizler, who was not involved in this study, added: "I think people must take into account that we can't do with these patients what we do with the general population, which is to try to get them to lose weight. The needs and intake of dialysis patients are very different."

Ms. Benner and Dr. Ikizler have disclosed no relevant financial relationships.

Renal Week 2009: American Society of Nephrology (ASN) 2009 Annual Meeting: Abstract SA-PO2567. Presented October 31, 2009.