營養(yǎng)不良

　　Malnutrition results from imbalance between the body's needs and the intake of nutrients, which can lead to syndromes of deficiency, dependency, toxicity, or obesity. Malnutrition includes undernutrition, in which nutrients are undersupplied, and overnutrition, in which nutrients are oversupplied. Undernutrition can result from inadequate intake; malabsorption; abnormal systemic loss of nutrients due to diarrhea, hemorrhage, renal failure, or excessive sweating; infection; or addiction to drugs. Overnutrition can result from overeating; insufficient exercise; overprescription of therapeutic diets, including parenteral nutrition; excess intake of vitamins, particularly pyridoxine (vitamin B6), niacin, and vitamins A and D; and excess intake of trace minerals.

　　營養(yǎng)不良由機體需要與營養(yǎng)素攝入之間不平衡所致，可引起缺乏、依賴、中毒或肥胖等癥。營養(yǎng)不良包括營養(yǎng)低下，即營養(yǎng)素供給不足，和營養(yǎng)過剩，即營養(yǎng)素供給過度。營養(yǎng)低下可由攝入不足、吸收不良、腹瀉、出血、腎衰或過度出汗而至營養(yǎng)素丟失、感染和吸毒等引起。營養(yǎng)過?？捎蓴z食過度、缺少鍛煉、治療膳食攝入過度（包括胃腸外營養(yǎng)）、過量攝入維生素，尤其是吡哆醇(維生素B6 )、尼克酸和維生素A和D、以及微量元素攝入過多所致。

　　Malnutrition (undernutrition and overnutrition) develops in stages, which usually require considerable time. First, nutrient levels in blood and/or tissues change, followed by intracellular changes in biochemical functions and structure. Ultimately, symptoms and signs appear; morbidity and mortality can result.

　　營養(yǎng)不良(營養(yǎng)低下和營養(yǎng)過剩)的發(fā)展是有階段的，通常需要相當(dāng)長的時間。首先，血液和/或組織中營養(yǎng)素水平改變，然后是生化功能和結(jié)構(gòu)發(fā)生改變，最終出現(xiàn)癥狀和體征，導(dǎo)致發(fā)病和死亡。

　　Early Detection

　　早期發(fā)現(xiàn)

　　The key to early detection is awareness that persons in certain circumstances have a high risk of undernutrition or overnutrition. Undernutrition is associated with poverty and social deprivation, occurring among the poor, including some immigrants arriving from developing countries. The risk of undernutrition is also greater at certain times in a person's life, ie, infancy, early childhood, adolescence, pregnancy and lactation, and old age. Overnutrition is associated with a sedentary lifestyle and the continuous availability of food in more affluent countries.

　　Persons in the following circumstances may be at risk of malnutrition.

　　早期發(fā)現(xiàn)的關(guān)鍵是要認識到，有些人是營養(yǎng)低下或營養(yǎng)過剩的高危人群。營養(yǎng)低下與貧窮和物質(zhì)匱乏有關(guān)，通常發(fā)生于窮人中，如來自發(fā)展中國家的移民。人一生中的某些階段患營養(yǎng)低下的危險性也很高，如嬰兒期、幼兒期、青少年期、妊娠哺乳期、以及老年期。營養(yǎng)過剩則與久坐習(xí)慣及富裕國家中食物豐富有關(guān)。

　　下列情況人群就有發(fā)生營養(yǎng)不良的危險。

　　Infancy and childhood: Because of the high demand for energy and essential nutrients, infants and children are at particular risk of undernutrition. Protein-energy malnutrition in children consuming inadequate amounts of protein, calories, and other nutrients is a particularly severe form of undernutrition that retards growth and development. Hemorrhagic disease of the newborn, a life-threatening disorder, is due to inadequate vitamin K. Deficiencies of iron, folic acid, vitamin C, copper, zinc, and vitamin A may occur in inadequately fed infants and children. In adolescence, nutritional requirements increase because the growth rate increases. Anorexia nervosa, a form of starvation, may affect adolescent girls.

　　嬰兒和兒童 嬰兒和兒童對能量和必需營養(yǎng)素的需要量高，其營養(yǎng)低下的危險性也高。兒童因蛋白質(zhì)、熱量和其他營養(yǎng)素攝入量不足造成的蛋白質(zhì)-能量型營養(yǎng)不良是一種尤為嚴重的營養(yǎng)不良，它會延緩兒童的生長和發(fā)育。新生兒出血性疾病可以危及生命，它是由維生素K攝入不足所致。嬰兒及兒童喂養(yǎng)不當(dāng)也會造成鐵、酸、維生素C、銅、鋅和維生素A等的不足。因生長加快，青少年對營養(yǎng)的需要增高。神經(jīng)性厭食癥是饑餓的一種形式，它對少女有影響。

　　Pregnancy and lactation: Requirements for all nutrients are increased during pregnancy and lactation. Aberrations of diet, including pica (the consumption of nonnutritive substances, such as clay and charcoal), are common in pregnancy. Anemia due to folic acid deficiency is common in pregnant women, especially those who have taken oral contraceptives. Folic acid supplements are now recommended for pregnant women to prevent neural tube defects (spina bifida) in their children. An exclusively breastfed infant can develop vitamin B12 deficiency if the mother is a vegan. An alcoholic mother may have a handicapped and stunted child with fetal alcohol syndrome, which is due to the effects of ethanol and malnutrition on fetal development.

　　妊娠和哺乳 在妊娠期和哺乳期，所有營養(yǎng)素的需要量都增高。飲食失常在孕期常見，如異食癖(食非營養(yǎng)性物質(zhì)如粘土和木炭)。因葉酸缺乏而引起的貧血在孕婦中也很常見同，尤其是口服避孕藥服用者?，F(xiàn)在已建議孕婦補充葉酸以預(yù)防兒童出現(xiàn)神經(jīng)管缺陷癥(脊柱裂)。如果母親是素食者，則完全母乳喂養(yǎng)的嬰兒就可能發(fā)生維生素B12缺乏癥。母親酗酒時，兒童出生后可能因胎兒酒精中毒綜合征造成殘疾或侏儒癥，其原因是酒精和營養(yǎng)不良影響胎兒發(fā)育。

　　Old age: A diminished sense of taste and smell, loneliness, physical and mental handicaps, immobility, and chronic illness can militate against adequate dietary intake in the elderly. Absorption is reduced, possibly contributing to iron deficiency, osteoporosis (also related to calcium deficiency), and osteomalacia due to lack of vitamin D and absence of exposure to sunshine.

　　With aging -- independent of disease or dietary deficiency -- there is progressive loss of lean body mass, amounting to about 10 kg in men and 5 kg in women. It accounts for the decrease in BMR, total body weight, skeletal mass, and height and for the increase in mean body fat (as a percentage of body weight) from about 20 to 30% in men and from 27 to 40% in women. These changes and a reduction in physical activity result in lower energy and protein requirements compared with those of younger adults.

　　老年人 味覺和嗅覺減退、孤獨、身體與精神障礙、不活動以及慢性疾病都會影響上老年人攝入足夠的食物。吸收功能減退，可能引起缺鐵、骨質(zhì)疏松癥(也與鈣不足有關(guān))及缺乏維生素D缺乏和陽光照射所致的骨軟化癥。

　　除了疾病和飲食不足以外，人體肌肉組織也會隨年齡老化而不斷減少，男性可減少約10kg，女性5kg。這也是基礎(chǔ)代謝率、總體重、骨骼體積和身高降低及平均體脂增高(按體重的百分比計)的原因，其中男性由20%增至30%，女性由27%增至40%。與中年相比，這些變化再加上身體活動減少就會引起能量和蛋白質(zhì)需要量的減少。

　　Chronic disease: In patients with chronic disease, malabsorption states (including those resulting from surgery) tend to impair the absorption of fat-soluble vitamins, vitamin B12, calcium, and iron. Liver disease impairs the storage of vitamins A and B12 and interferes with the metabolism of protein and energy sources. Patients with kidney disease, including those on dialysis, are prone to develop deficiencies of protein, iron, and vitamin D. Some patients with cancer and many with AIDS have anorexia, which complicates treatment. In patients receiving long-term home parenteral nutrition--most commonly after total or near-total resection of the gut--vitamin and trace mineral deficiencies must be especially guarded against. A physician should ensure that biotin, vitamin K, selenium, molybdenum, manganese, and zinc are adequately supplied.

　　慢性疾病 慢性疾病患者吸收障礙(包括外科手術(shù)引起的吸收障礙)極易損害脂溶性維生素、維生素B12、鈣和鐵的吸收。肝臟疾病破壞維生素A和維生素B12的貯存，干擾蛋白質(zhì)和能量物質(zhì)的代謝。腎臟疾病患者，包括透析治療者，容易出現(xiàn)蛋白質(zhì)、鐵和維生素D的缺乏。有些癌癥患者和眾多AIDS患者都有神經(jīng)性厭食癥，這使得治療更加困難。在家進行長期胃腸外營養(yǎng)治療的病人，通常為腸全切除或次全切除病人，應(yīng)特別警惕維生素和微量元素缺乏。醫(yī)生應(yīng)確保生物素、維生素K、硒、鉬、鎂和鋅的充足供給。

　　Vegetarian diets: The most common form of vegetarianism is ovo-lacto vegetarianism, in which meat and fish are eschewed but eggs and dairy products are eaten. Iron deficiency is the only risk. Ovo-lacto vegetarians tend to live longer and to develop fewer chronic disabling conditions than their meat-eating peers. However, their lifestyle usually includes regular exercise and abstention from alcohol and tobacco, which may contribute to their better health. Vegans consume no animal products and are susceptible to vitamin B12 deficiency. Yeast extracts and oriental-style fermented foods provide this vitamin. Intake of calcium, iron, and zinc also tends to be low. A fruitarian diet, which consists solely of fruit, is deficient in protein, salt, and many micronutrients and is not recommended.

　　素食 最常見的素食者是乳蛋素食者，即不吃肉和魚而吃雞蛋和乳制品。唯一的危險是缺鐵。與食肉者想比，乳蛋素食者往往壽命更長，得慢性致殘疾病也少。在日常生活中，他們經(jīng)常鍛煉，不沾煙酒，這也有助于他們的健康。素食者不吃任何動物性食物，易患維生素B12缺乏癥。酵母精和東方式的發(fā)酵食物能提供這種維生素。但鈣、鐵和鋅的攝入量往往很低。果蔬飲食是由水果組成的，缺乏蛋白質(zhì)、鹽和多種微量營養(yǎng)素，也不推薦使用。

　　Fad diets: Many commercial diets are claimed to enhance well-being or reduce weight. A physician should be alert to early evidence of nutrient deficiency or toxicity in patients adhering to them. Such diets have resulted in frank vitamin, mineral, and protein deficiency states and cardiac, renal, and metabolic disorders as well as some deaths. Very low calorie diets (= 1 quart of hard liquor per day lose weight and become undernourished. Drug addicts are usually emaciated. Alcoholism is the most common cause of thiamine deficiency in the USA and may lead to deficiencies of magnesium, zinc, and other vitamins.

　　酗酒或毒品依賴 眾所周知，酗酒或吸毒病人的飲食習(xí)慣問答是不可靠的，因此，明智而審慎地向其親友詢問是必要的。成癮導(dǎo)致生活方式紊亂，無視營養(yǎng)是否足夠。營養(yǎng)素的吸收和代謝也受到損害。高度酒有毒，且能導(dǎo)致組織損傷，尤其是損傷胃腸道、肝臟、胰臟、腦和外周神經(jīng)系統(tǒng)。啤酒飲用者由于不斷飲用食物，會導(dǎo)致其體重增加。但每天白酒大于等于1L的嗜酒者體重會減輕，導(dǎo)致營養(yǎng)低下。吸毒上癮的人通常憔悴消瘦。在美國，酒精中毒是導(dǎo)致硫胺素缺乏的最常見因素，現(xiàn)時也可以導(dǎo)致鎂、鋅和某些維生素的缺乏。

　　Diagnosis

　　診斷

　　The diagnosis of malnutrition is based on results of the medical and diet history, physical examination, and selected laboratory tests. Results are compared with norms of weight for height, body mass index (BMI), dietary intake, physical findings, and plasma levels of nutrients and nutrient-dependent substances, such as hemoglobin, thyroid hormones, transferrin, and albumin.

　　應(yīng)根據(jù)病史和飲食史、體檢及專門的實驗室檢查結(jié)果對營養(yǎng)不良作出診斷。并將診斷結(jié)果與身高體重正常值、體質(zhì)指數(shù)(BMI)、攝入量、體檢結(jié)果、血漿中營養(yǎng)素及營養(yǎng)素依賴性物質(zhì)如血紅蛋白、甲狀腺激素、轉(zhuǎn)鐵蛋白和白蛋白的水平等進行比較。

　　History: A history of poor appetite, GI disturbance, and recent sizable weight loss suggests the possibility of malnutrition. A history of bleeding may indicate iron deficiency. Chronic use of alcohol, cocaine, heroin, immunosuppressants, or certain antibiotics and anticonvulsants raises questions about the adequacy of vitamin and mineral nutrition. A diet history may reveal food faddism, lack of variety, or inadequate or excessive intake of energy and essential nutrients.

　　病史 食欲差、胃腸道障礙及近期體重明顯減低等病史均提示有營養(yǎng)不良可能。出血史表明缺鐵。長期使用酒精、可卡因、海洛因、免疫抑制劑及抗驚厥劑會使維生素和礦物質(zhì)是否充足成為問題。通過膳食史可以發(fā)現(xiàn)是否是時尚飲食、食物品種是否單一、能量和必需營養(yǎng)素攝入不足或過多等情況。

　　Physical examination: Significant changes in body composition and organ function may suggest malnutrition as a cause. The skin should be examined for dryness, scaliness, atrophy, petechiae, and ecchymoses, and the mouth for angular stomatitis, glossitis, swollen or bleeding gums, and decayed teeth. Depigmentation of the hair and spooned nails point to malnutrition. The musculature should be examined for size, strength, and tenderness. A neurologic examination may detect disorientation, an abnormal gait, altered reflexes, and sensory or motor neuron abnormalities. Painful bones and joints, osteopenia, and distortions in the shape or size of bones (eg, rachitic rosary) may indicate current or past malnutrition.

　　體格檢查 體格和器官功能方面的顯著改變可以提示營養(yǎng)不良因素。皮膚應(yīng)檢查有無干燥、鱗屑、增生、瘀點及瘀斑；口腔應(yīng)檢查有無口角炎、舌炎、腫脹、齒齦出血和齲齒。頭發(fā)脫色和匙狀甲表明營養(yǎng)不良。肌肉系統(tǒng)應(yīng)檢查其大小、強度及柔韌性。神經(jīng)系統(tǒng)檢查可發(fā)現(xiàn)定位異常、步態(tài)異常、反射改變及感覺或運動神經(jīng)元異常。骨和關(guān)節(jié)痛疼、骨質(zhì)減少及骨的形狀或大小改變(如佝僂病性串珠)均表明目前或過去營養(yǎng)不良。

　　Anthropometric measurements are essential to diagnosis. Nutritional status can be classified on the basis of BMI. The triceps skinfold (TSF) estimates the amount of body fat within 20% and is therefore useful in determining the body's energy stores. Based on the midarm muscle area, an approximate measure of lean body mass, muscle mass may be classified as adequate, marginal, depleted, or wasted. form bhshhw.cn

　　人體測量數(shù)據(jù)對診斷是至關(guān)重要。營養(yǎng)狀態(tài)可以根據(jù)BMI進行分類。三頭肌皮褶厚度(TSF)可以估計20%之內(nèi)的體脂，因此，在確定機體能量貯存方面很有用。根據(jù)上臂肌面積可大致確定瘦體重，如分為合適、臨界、耗竭或消瘦幾類。

　　Laboratory tests: A CBC and measurement of certain plasma proteins that reflect the adequacy of amino acid nutrition (albumin, prealbumin, and transferrin) aid in the diagnosis of malnutrition, as does measurement of plasma lipids and related lipoproteins. Abnormal electrolyte levels may point to a mineral deficiency or a defect in ion homeostasis. Fat- and water-soluble vitamins can be measured in plasma and urine. Skin tests using antigens are used to evaluate cell-mediated immunity. Various imaging techniques (x-ray, CT, and MRI) may be helpful.

　　實驗室檢查 全血細胞計數(shù)及反映氨基酸營養(yǎng)程度的某些蛋白質(zhì) (白蛋白、前白蛋白和轉(zhuǎn)鐵蛋白) 測定數(shù)據(jù)有助于營養(yǎng)不良的診斷。血漿脂類和相關(guān)的脂蛋白測定也有幫助。電解質(zhì)異?？赡鼙砻鞯V物質(zhì)缺乏或離子的內(nèi)穩(wěn)態(tài)受到破壞。脂溶性和水溶性維生素可在血漿和尿中測得。抗原皮試用于評估細胞免疫。各種影像技術(shù)(X線、CT和MRI)也有幫助。

　　Surgical procedures place additional stress on undernourished persons. Indicators of malnutrition have been used to develop a prognostic nutritional index (PNI), a linear predictive model of increased morbidity and mortality after surgical procedures. The formula for PNI uses serum albumin (A) in g/dL, TSF in mm, serum transferrin (TFN) in mg/dL, and delayed hypersensitivity (DH) response (0 to 2), measured by leukocyte migration inhibition, transformation, and cytotoxicity tests.

　　手術(shù)可增加營養(yǎng)低下者應(yīng)激反應(yīng)。營養(yǎng)不良的指標(biāo)已被用于診斷營養(yǎng)預(yù)后指數(shù)(PNI)，這是對外科手術(shù)后發(fā)病率和死亡率增加的一種線性預(yù)后模式。血清白蛋白g/dl(A)、三頭肌皮褶厚度mm(TSF)、血清運鐵蛋白mg/dl(TFN)、以及用白細胞移動抑制、轉(zhuǎn)化、細胞毒性試驗檢測的遲發(fā)性過敏反應(yīng)(0~2)(DH)均用于PNI公式中：PNI%＝158-16.6(A)-0.78(TSF)-0.2(TFN)-5.8(DH)

　　For example, a well-nourished patient with A = 4.8, TSF = 14, TFN = 250, and DH = 2 has a PNI of 158.0 - 152.2, or a 5.8% chance of complications. A malnourished patient with abnormal indexes (A = 2.8, TSF = 9, TFN = 180, and DH = 1) has a PNI of 158 - 95.3, or a 62.7% chance of complications.

　　例如，一個營養(yǎng)良好的病人，A＝4.8，TSF＝14，TFN＝250，DH＝2，其PNI為158.0~152.2，或者說他患并發(fā)癥的機會為5.8%。一個指標(biāo)異常的營養(yǎng)不良病人(A＝2.8，TSF＝9，TFN＝180，DH＝1)，其PNI為158~95.3，或他患并發(fā)癥的機會為62.7%。