透析病人攝取特殊栽植低鉀蔬菜對血鉀之影響

背景：人體中的鉀離子(potassium，K+)約有90%由腎臟調節，由於末期腎臟病者(ESRD)喪失調節鉀離子的能力，需採取血液透析(hemodialysis)等替代療法取代原本部份的腎臟功能。血鉀異常將會增加虛弱、抽筋、心律失調甚至死亡等風險，需採限鉀飲食及食材汆燙等烹調方式。鉀大量存在於蔬果中，使得部份病人選擇減少食用蔬果，故近年世界各地以農業技術栽植含鉀低的蔬菜(low potassium vegetable)提供腎病者，但迄今尚無攝取低鉀蔬菜對腎病病人血鉀影響的臨床試驗。本研究目的為(1)探討規律門診血液透析受試者之飲食狀況(2)分析攝取低鉀蔬菜對血鉀之影響。方法：本研究為隨機分派之開放式、交叉試驗設計之人體試驗，於中山醫學大學附設醫院(CSMUH)透析中心召募同意受試者，並納入30名受試者分配為兩組。本研究以24小時飲食回憶法收集受試者飲食記錄，於調整烹調方式下提供試驗蔬菜(不經汆燙直接烹調的低鉀蔬菜、經汆燙至少1分鐘後再烹調的市售蔬菜)交叉攝取各一週，介入期間收集血液生化數值。資料結果以描述性統計、獨立樣本t檢定、成對樣本t檢定、皮爾森積差及逐步迴歸進行分析，當p<0.05代表具有統計學上之意義。結果：本研究發現受試者所攝取的熱量、蛋白質、膳食纖維皆明顯未達血液透析營養建議攝取量與國人飲食建議量，受試者中僅有2位(6.7%)可達每日5份蔬果的健康人群建議攝取量。受試者攝取低鉀栽植前後的血鉀並無顯著差異(4.59、4.59 mmol/L，P=0.968)；進一步探討相關因子與血鉀變化的相關性後，發現隨著熱量攝取增加可預測影響血鉀變化。結論：本研究結果呈現血液透析病人食用直接烹調之低鉀蔬菜與經汆燙後市售普通蔬菜相較並無造成血鉀不同，但長期食用是否會對人體造成其它影響，仍待後續進一步研究探討。

IntroductionPatients on hemodialysis (HD) are more at risk of hyperkalemia as the renal secretion of K+ is decreased in HD patients. Hyperkalemia is linked to arrhythmia, sudden cardiac death, general weakness, and muscle cramps. A low potassium diet is usually needed to avoid hyperkalemia in HD patients. Many fresh fruits and vegetables are high in potassium. Low potassium vegetables were developed with agricultural techniques to reduce hyperkalemia in HD patients. However, clinical trials on low potassium vegetables in ESRD patients are currently not available.The study investigates the dietary status of chronic HD patients and the effect of low potassium vegetables on serum potassium in HD patients.MethodsThis is a randomize-controlled,cross-over trial in HD patients of Chung Shan Medical University Hospital(CSMUH). Thirty patients were assigned to two groups (low-potassium vegetables without blanching and commercially available vegetables blanching for at least one minute for one week, then cross-over). The 24-hour diet recall method(24 HDR) was used to collect the diet records. Serum potassium, sodium, calcium, phosphorus were measured before and after the study.Data are analyzed by descriptive statistics,independent sample t-test, paired sample t-test, Pearson test,and multivariable stepwise regression. A P<0.05 was considered statistically significant.ResultsCalorie, protein, and dietary fiber intake are lower than the recommended nutritional intake for HD patients and the recommended dietary intake for Taiwanese. Two patients (6.7%) had five portions of vegetables per day: the recommended intake for healthy people of fruits and vegetables.There was no significant difference between the serum potassium before and after the low-potassium vegetables (4.59 and 4.59mmol/L, P=0.968). A higher calorie intake was linked to the changes in serum potassium in multivariable stepwise regression.ConclusionsThe serum potassium was not different in hemodialysis patients with and without low-potassium vegetables. Daily calories intake is associated with serum potassium levels in patients on hemodialysis.