Protein Energy Undernutrition

Causes

In nursing home residents, weight loss may occur because of any of several reasons. In some cases, the physician can do little to stop the weight loss (for example, when the cause is cancer or end-stage disease such as that seen with cardiac cachexia). However, because most causes of weight loss in elderly patients can be treated, the physician should concentrate on identifying undernutrition and on reversing the causes and risk factors of malnutrition [10] (Table 2). A recent study of weight loss among community nursing home residents suggested that a potential cause could be found in most cases [11].

One cause of weight loss is a decrease in the resting metabolic rate. One study reported decreases of 20% in elderly men and 13% in elderly women [12]. A decrease in the resting metabolic rate is accompanied by diminished food intake, which may be due to a decrease in the endogenous opioid (dynorphin) feeding drive and an increase in the satiation effect of the gut hormone cholecystokinin [13]. Malnutrition, in turn, increases circulating cholecystokinin levels in older persons, which may further decrease appetite [14].

Adverse drug effects and depression are the most common reversible causes of protein energy undernutrition. Medications can induce weight loss by causing anorexia, nausea, vomiting, diarrhea, constipation, cognitive disturbance, or increased metabolism. Medications that commonly cause these side effects include digitalis, psychotropic agents, fluoxetine, sertraline, and theophylline (anorexia); erythromycin, aspirin, and nonsteroidal antiinflammatory drugs (gastrointestinal irritation); narcotics and calcium channel antagonists (constipation); theophylline suspension (diarrhea due to sorbitol vehicle); all psychotropic agents, clonidine, and metoclopramide (cognitive disturbance); and excess dosage of L-thyroxine or theophylline (increased metabolism). Recently we noted that in some residents (after the OBRA 1987 mandate) who received long-term therapy with psychotropic drugs, severe weight loss developed when the therapy was discontinued [11]. Depression occurs in 8% to 38% of nursing home residents [15]. Depression is more likely to be associated with anorexia and weight loss in older persons than in younger persons [15]. Katz and colleagues [16] reported that, in residents, "failure to thrive" was closely correlated with depression, and an analysis of 6832 minimum data sets from 202 nursing homes in seven states showed that depression was associated with weight loss [17]. Poor oral intake, eating dependency, decubiti, and chewing problems were associated with both low body mass index and weight loss. In one community nursing home study, one third of residents with weight loss had depression [11], and in another study patients regained their weight after depression was appropriately treated [18].

Anorexia nervosa has also been reported in the geriatric population. In some patients, it may be the recurrence of a preexisting condition, but in others anorexia nervosa occurs for the first time in later life, in which case it is termed anorexia tardive. These patients may display certain oral control patterns, such as avoiding eating when hungry [19]. Thus, one needs to consider abnormal eating attitudes when looking for causes of weight loss.

In the case of late-life paranoia, the resident may believe that she or he is being poisoned and refuse to eat. Other residents refuse to eat as a way of manipulating the staff. Older persons who see that a malnourished resident receives special attention during feeding times may stop eating to increase the time that the staff spend socializing with them.

Swallowing disorders are another cause of decreased food intake, and these may result from cerebrovascular accidents, neuromuscular disorders, generalized weakness, dementia, or Parkinson disease. Residents with Parkinson disease and Huntington chorea also lose weight because of the increased metabolism associated with their increased movements.

At least 80% of nursing home residents have some degree of tooth loss [20]. Half of the residents who wear dentures need replacement or relining of their dentures, and approximately one third of residents have mucosal lesions. In another study, untreated dental decay was present in 70% of residents [21]. Oral health factors such as these can result in decreased nutrient intake. Although two community-based studies failed to find a correlation between oral health and weight loss [22, 23], a Veterans Affairs-based study found that oral health problems were a significant predictor of weight loss [24]. In addition, problems with olfaction, taste, and xerostomia may decrease the enjoyment of eating. Nursing home residents often do not receive adequate dental care. Increasing the use of dental technicians may be one solution to this problem.

Nursing homes that are funded primarily through Medicaid are limited in what they can spend on food. Thus, diets may become monotonous, and it may be impossible for the facility to meet individual dietary preferences or to cater to the preferences of separate ethnic groups. The lack of reimbursement for food supplements tends to discourage the early use of supplements to prevent the development of malnutrition. Recently, it has been demonstrated in Veterans Affairs nursing homes that the nutritional status of residents can be related to the cost of care, with better nutritional status seen in residents when more money was spent on care [25].

A large proportion of patients with cognitive impairment have protein or energy undernutrition despite adequate reported intakes [26]. Many cognitively impaired residents cannot feed themselves, and a disproportionate amount of overall nursing home costs are spent on the management of "dependent eaters." In one study, the inability to feed oneself was the reason for institutionalization in 18% of patients [27]. Causes of weight loss in patients with dementia include swallowing difficulties (especially in patients with multi-infarct dementia), insufficient time spent on feeding because adequate staff are not available, and infections caused by the fact that protein needs are not being met. Residents who pace all day may need greater nutritional intake to compensate for their energy expenditure. No evidence of an increased catabolic state that causes weight loss has been found in cognitively impaired persons [28].

Metabolic disorders such as hyperthyroidism and hyperparathyroidism are not uncommon causes of weight loss in older persons, but both may be overlooked because of unusual presentations in this age group. Patients may present with decreases in serum albumin, the carrier protein for calcium, which may obscure the presence of the hypercalcemia of hyperparathyroidism for the hurried physician; however, free calcium levels or simultaneous albumin levels clarify the diagnosis. Persons with hyperthyroidism may have a coexisting euthyroid sick syndrome, resulting in high normal thyroid function levels and making diagnosis extremely complicated. Pheochromocytoma should be considered in residents who are hypertensive despite weight loss.

Older persons who have tremors may spill much of their food simply in transporting it from the plate to the mouth; a heavy-handled spoon is easier for these persons to hold and helps them avoid such "spills." Persons with stroke disability may fail to eat meat because it is too difficult for them to cut. In this case, a rocker bottom knife may enable such persons to feed themselves. Residents of nursing homes may also find it difficult to eat because of inappropriate positioning at the table and because of weakness.

Malabsorption should always be considered as a cause of malnutrition. The differential diagnosis includes late-life onset of gluten enteropathy, particularly in residents with diabetes mellitus.

Low-salt, low-cholesterol diets are unpalatable and are often associated with protein energy malnutrition and postural hypotension in older persons. Two recent studies have shown that weight loss, low albumin levels, and orthostatism are associated with therapeutic diets [29, 30]. In the nursing home, special diets should therefore be avoided whenever possible. Social situations may be another cause of weight loss. Institutionalization itself produces feelings of loss of control and isolation, which can lead to a refusal to eat. Some residents find it impossible to eat when they have to share dining space with residents who have catheters, ulcers, or nasogastric tubes or who are incontinent. Residents may also find it difficult to eat with cognitively impaired residents, who may have unappetizing hygiene and eating habits.

Illnesses, such as chronic infections, are another common cause of weight loss. In persons with chronic infections, weight loss is probably secondary to the release of cytokines such as interferon or interleukins, whereas in the case of local infection (for example, with Candida species), weight loss may result from dysphagia. Tuberculosis may present insidiously with weight loss. Residents with chronic obstructive pulmonary disease often have protein energy undernutrition related both to an increase in energy expenditure (caused by the use of accessory muscles for breathing) and to a decrease in food intake secondary to a decrease in oxygen saturation associated with feeding.

Occasionally, older persons develop early satiation and can eat only a small proportion of their meals. During the last decade, we have successfully treated several of these persons with nitrates, believing that they had ischemic bowel disease. Recently, nitric oxide has been shown to facilitate food intake by allowing adaptive relaxation of the fundus of the stomach [31]. In ongoing studies, one of us (JEM) has found that in older rats, there is a decrease in messenger RNA for nitric oxide synthase and a nitric oxide synthase inhibitor induces an increased inhibition of food intake.

Evaluation

Recognizing the many risk factors for poor nutritional status in nursing home residents is the key to a successful evaluation and treatment plan. An interdisciplinary team can be helpful in this respect. Sometimes the simplest maneuvers are the most effective; for example, the aides or volunteers who assist with feeding can provide invaluable information about total consumption, which is likely to be more useful than calorie counts. They can also provide the dietitian with information about the residents' likes and dislikes of particular foods, and they can identify which patients have swallowing problems. The dietitian can spend time with patients discussing lifelong food habits and, together with the social worker, plan meals in accordance with the cultural diversity that may exist in a particular institution. The nursing staff can help identify persons who are compatible with each other at mealtimes, and the pharmacist can identify various potential drug-nutrient interactions. Nursing home personnel can assist in evaluation, through use of formal screening tests, of mental status (for example, the Folstein Mini-Mental Status Examination), affect (for example, Yesavage depression scale), and nutritional attitudes (for example, the EAT-26 questionnaire) [19]. Without input from the staff, the physician is not likely to be successful in evaluation and treatment.

Although the time that the physician is available in the nursing home remains limited, obtaining a history from the resident (when possible), staff, and family members remains the cornerstone to making the correct diagnosis. In taking the history, it is important to determine if the following are present: weakness, changes in the ability to taste, olfactory changes, abdominal pain, decreased appetite, nausea, vomiting, diarrhea, constipation, dysphagia, problems with dentition, and changes in mental or functional status. Disease states associated with weight loss are numerous and may include anemia, hip fractures, depression, dementia, decubiti, hypothyroidism, and cancer. A detailed medical and medication history is also necessary because of the numerous drug-nutrient interactions (Table 3). On physical examination, one may find obvious signs of protein energy undernutrition, such as alopecia, dependent edema, glossitis, skin desquamation, and dry, depigmented hair.

A serum albumin level less than 35 g/L has been used as the gold standard for identifying patients at risk for malnutrition. The literature provides ample support to suggest that patients with low albumin levels are at increased risk for infection, decubitus ulcers, prolonged nursing home stays, and mortality. However, the albumin level may appear to be normal on admission because of its long half-life or may be artificially high because of dehydration, and therefore, although it is helpful, the albumin level may not adequately reflect the patient's true nutritional state. Also, some data indicate that patients with albumin levels between 35 and 39 g/L have the same mortality rate as those whose levels are less than 35 g/L, suggesting that the practitioner may have to institute nutritional support earlier than previously recognized. Some patients present with marasmus—that is, they are malnourished on the basis of weight loss but maintain normal serum albumin levels. Further, because serum albumin is an acute-phase reactant, low serum albumin levels may represent an inflammatory response to the release of cytokines. Thus, although it is helpful, the serum albumin level is not necessarily the most accurate indicator of nutritional status.

Weight trends, when combined with the serum albumin level, may help better identify which residents are at risk for malnutrition. Patients who have had a weight loss of 10% or more of their total body weight over 6 months, 7.5% or more over 3 months, or 5% or more over 1 month should be studied. Patients who weight less than 90% of age-matched controls likewise need to be evaluated. We strongly recommend that residents be weighed at least biweekly during the first month of their stay in the nursing home, especially those who are either returning from or being transferred from an acute hospital stay. In our experience, many of these residents need intervention to regain weight or improve their protein status. Furthermore, although accurate weights are difficult to obtain in many nursing homes, weight accuracy is essential in quality assurance programs.

Except for Master and colleagues' table [32], weight-for-height tables for the elderly have not been standardized. Estimates of height given during the history are also frequently inadequate, and heights are difficult to measure in some residents (for example, those who are bedridden). Alternatives to height measurement have been developed, such as knee-height and armspan measurements. However, although weight-for-height is valuable in evaluating nutritional status, studying weight trends may be more useful.

Several studies suggest that a low serum cholesterol level (< 4 mmol/L) may be another useful marker of inadequate nutrition. Rudman and colleagues [5] noted a tenfold increase in mortality in patients with low cholesterol levels compared with patients with cholesterol levels of 4 mmol/L or greater. Forette and colleagues [33] likewise found low cholesterol levels to be a predictor of increased mortality in older women. Cholesterol levels should be checked in residents returning to the nursing home after an acute hospital stay, because during an acute hospital stay, elderly persons may develop hypocholesterolemia. Low cholesterol levels are also associated with cognitive impairment [34] and depression [35] in older persons.

Other methods to evaluate altered nutritional status include anthropometrics other than height and weight measurements, such as measurement of skinfold thickness or mid-arm circumference, lymphocyte count, and reactivity to skin testing. Skinfold measurements (that is, triceps and subscapular) are poorly standardized in older persons, however, and are not inter-rater reliable. Also, the lymphocyte count and presence or absence of anergy can be affected by numerous other disease states and, by themselves, add little to the evaluation process. In fact, anergy and lymphocytopenia have been reported in 10% of elderly persons, with no apparent pathology. Nevertheless, anergy in nursing homes is often associated with more severe conditions; anergic residents are more likely to have low body weight and have low serum albumin levels, and a significant association between 1-year mortality rates and anergy and albumin levels less than 35 g/L has been reported [36, 37]. The prognosis is even worse when anergy is combined with other low nutritional variables.

Management

The management of nutritional problems should be interdisciplinary and individualized. Malnourished residents should be encouraged to ingest as many calories orally as possible, but most of the more frail and compromised residents will not be able to keep up with the nutritional intake necessary to reverse their deficits. Commercially available products, either single nutrients or liquid meal replacements, should be tried before invasive techniques are used. Also, undernourished residents should be asked about their favorite foods and allowed ad libitum access to these foods. Flexible mealtimes may also help encourage food intake.

When one is considering the nutritional needs of residents, the major emphasis should be placed on caloric needs. Caloric needs can be calculated from the formula:

(1)

RMR is calculated using the Harris-Benedict equation:

(2)

Recently, Poehlman [28] created new equations for resting metabolic rate for older persons, which in time may prove more useful than the classic Harris-Benedict equation. In these new equations, diet-induced thermogenesis is calculated as 5% of the total energy requirements. Energy estimates for activity are 400 kcal/d for bedridden individuals, 600 kcal/d for residents who are not bedridden but who are relatively inactive, and 1200 to 1800 kcal/d for "wanderers" (residents who roam the nursing home facility freely). A further 10% of the resting metabolic rate is added when a recurrent infection or chronic obstructive pulmonary disease is present. In most cases, residents tolerate the full calculated amount of calories from admission. If osmotic diarrhea develops, caloric intake should be halved and then increased at the rate of approximately 10 kcal/h daily (or 240 kcal/d) until the appropriate caloric amount is reached. One should bear in mind, however, that many residents who are assumed to have osmotic diarrhea may later be found to have diarrhea due to pathologic causes-for example, Clostridium difficile infection or fecal impaction with overflow diarrhea.

Caloric intake in residents can be improved by some apparently simple maneuvers. A semicircular table that allows one aide to feed as many as three to four residents at the same time is particularly recommended. As discussed earlier, use of a heavy-handled spoon may decrease food spillage in persons with tremors, and residents with stroke disability may benefit from the use of a rocker-bottom knife, which allows them to cut their own food. Residents with swallowing problems should be positioned as erectly as possible at the table and kept from leaning forward to the plate. Avoidance of special diets (for example, low-salt, low-cholesterol and diabetic diets), except when absolutely necessary, prevents protein energy undernutrition in residents.

A nasoenteric tube may be considered for alert and functional residents who require a short course ( 2 weeks) of supplementation such as those admitted for rehabilitation after hip or knee surgery, those with decubitus ulcers, and those transferred back from the acute hospital setting. One might attempt these feedings at night (with the head of the bed elevated) to avoid interference with daytime eating.

Duodenal feeding tubes are fraught with difficulty. Radiographic evidence that the tube has passed the pyloric sphincter may be difficult to obtain. Although metoclopramide (Reglan; ACh. Robins Company, Inc., Richmond, Virginia) is often used to facilitate tube placement by increasing stomach motility, studies suggest that it does not improve success with tube intubation and may, in fact, worsen the mental state of the patient.

More patients are now entering the nursing home who have already had percutaneous endoscopically placed gastrostomy or jejunostomy tubes placed. It is possible that both of these feeding tubes are associated with fewer instances of aspiration or self-extubation than nasogastric tubes, but this has not been proven. Jejunostomy tubes should be reserved for the comatose patient who is more likely to aspirate. Feedings placed in jejunostomy tubes must be partially digested.

Although a full discussion of the many formulas currently available for enteral feeding is beyond the scope of this article, some general comments are appropriate. Lactose-free iso-osmolar products to minimize diarrhea are favored by some clinicians. Others prefer supplements with added fiber to improve bowel function. Protein (16% to 20%) should be considered in patients with increased nitrogen needs, such as those with decubiti or infection; however, the overall caloric intake must be adequate to prevent protein metabolism as the source of energy. Finally, the physician should be aware that some polymeric diets may be missing some micronutrients; residents who are to receive tube feeding long term should continue to be weighed after these diets have been instituted, because it is not uncommon for these patients to be chronically underfed.

The complications of enteral nutrition are numerous and include mechanical complications caused by tube placement, electrolyte imbalance, hyperglycemia, and diarrhea. Metabolic derangements are less likely if 18-hour infusions are provided as opposed to 24-hour infusions or bolus feedings. A hyperosmolar state can be avoided by flushing the feeding tube with 100 to 200 mL of free water every 4 to 6 hours.

Finally, it should be recognized that long-term tube feeding is not necessarily appropriate for all residents. The resident or responsible family member has the right to exert his or her autonomy and refuse tube feeding.

Tube Feedings: New Indications

Although physicians have traditionally reserved the use of feeding tubes for the "maintenance" of end-stage residents or for residents who are no longer able to feed themselves, the role of nutritional support may be changing, especially for those residents admitted to the nursing home for rehabilitation. Recent data suggest that the early use of enteral supplementation may decrease morbidity and mortality. For example, rehabilitation time was shortened and mortality decreased in a group of women with femoral neck fractures who received supplementary tube feedings of 1000 calories each night while they were asleep [38]. Median rehabilitation time was significantly decreased from the time of operation to the time of independent mobility but not from the time of operation to the time of weight bearing with support. This suggests a 10- to 14-day lag time from the institution of supplementation to improvement in muscle strength and functional status. In another study, immediate and 6-month mortality rates were lower in orthopedic patients undergoing rehabilitation after hip fracture who received supplementary tube feedings of 250 calories per day [39]. Finally, a group of patients with chronic obstructive pulmonary disease who received enteral supplementation of 1000 calories more than their usual intake had improved lung function, as determined by maximum expiratory pressures and mean sustained inspiratory pressures [40]. Aggressive feeding of high-protein diets can also accelerate healing in persons with decubitus ulcers [41].

Another group of patients that may benefit from early intervention with enteral supplementation are those who are depressed. Identifying and treating depression is frequently delayed, with concomitant loss of weight. One may be reluctant to label a newly admitted resident as depressed, considering the numerous losses new residents tend to experience, including loss of independence. However, if this diagnosis is not considered, valuable intervention time is wasted. Furthermore, in the resident with severe cachexia and depression, it may take some time before therapy is effective. Therefore, the depressed resident is an ideal candidate for aggressive and early nutritional intervention with tube feedings. For depressed residents who do not respond to treatment with antidepressants and psychological support, electroconvulsive therapy is the treatment of choice.

Ethical issues are frequently raised regarding the level of aggressiveness in treating patients with dementia who have had weight loss, including whether or not to use tube feeding. This should be less of a problem as more residents early in the course of the disease are advised on living wills and durable power of attorney. Another concern is that the confused resident will dislodge the tube. However, in one study, 50% of severely demented residents had their tubes in place for more than 1 year [36].

A final group of residents likely to benefit from early aggressive feedings are those transferred back from the acute hospital setting. Many of these patients have had procedures for which they were to receive nothing by mouth or were too sick to feed themselves, with no one attending to their nutritional status during the hospital stay. Others may have found it difficult to eat because they were in an unfamiliar environment or because the diet was too restrictive. Because a catabolic phase generally occurs 3 to 10 days after illness or trauma and patients may be discharged from the hospital early (owing to Diagnosis Related Groups), these patients would benefit greatly from nutritional resuscitation.

Appetite Stimulants

In one study in which malnourished nursing home residents received recombinant growth hormone, muscle mass improved and weight gain was noted [42]. Medroxyprogesterone acetate has been reported to stimulate food intake in persons with cancer-related cachexia [43]; however, in our experience, it often causes severe constipation in older persons. Serotonin antagonists have also been administered to nursing home residents with mixed results. As mentioned previously, nitrates may enhance food intake in persons with early satiation. Also, glyceryl trinitrate (2.6 mg) has been found to reduce abnormal antral filling in patients with functional dyspepsia [44], and antidepressant drugs may increase food intake in depressed residents.

Vitamins

Low blood levels of numerous vitamins have been found in many of nursing home residents [6]. These residents tend to have low caloric intakes, although drug-nutrient interactions may also account for these low blood levels (Table 3). Illness, too, may alter the absorption, metabolism, or secretion of some vitamins. The consequences of these low vitamin levels is uncertain. Skin changes suggestive of vitamin deficiencies that are commonly found in residents include hemorrhage, cheilosis, skin dryness, and a bald tongue. Vitamin C is widely used to promote decubitus ulcer healing [1]. Low levels of vitamins B₁, B₂, and C have been correlated with cognitive dysfunction [45], and thiamine supplementation has been shown to improve cognitive function in community-dwelling older persons who have vitamin deficiencies [46]. Vitamin supplementation resulted in a decrease in infections in older community dwellers [9], and vitamin C may be associated with prolongation of life in men (although not in women) [47]. The few interventional studies that have been done Table 4 do not clearly recommend that nursing home residents receive vitamin supplementation if caloric intake is adequate. However, large controlled trials are needed to resolve this issue.

Vitamin B₁₂ deficiency is a separate case. Vitamin B₁₂ deficiency may be due to an autoimmune disease process resulting in lack of intrinsic factor (that is, pernicious anemia). These persons are at increased risk for having other autoimmune endocrine disorders, such as diabetes mellitus, hypothyroidism, adrenal insufficiency, and celiac disease. Others develop vitamin B₁₂ deficiency because of poor dietary intake, bacterial overgrowth, or malabsorption, which may occur because of an inability to split vitamin B₁₂ from its protein complex in food. The results of the Schilling test can be normal in patients with vitamin B₁₂ deficiency due to this failure to split vitamin B₁₂ from its protein complex [48]. Persons with Alzheimer dementia may be particularly prone to vitamin B₁₂ deficiency [49]. In patients with neuropsychiatric abnormalities, vitamin B₁₂ deficiency can occur without anemia or macrocytosis [50]. Finally, normal vitamin B₁₂ levels do not necessarily rule out vitamin B₁₂ deficiency: More than half of persons with vitamin B₁₂ levels between 200 and 300 pg/mL may have deficiency as shown by elevated methylmalonic acid and homocysteine in the urine [51]. Thus, urinary measurement of these metabolites may be necessary to make or rule out the diagnosis of vitamin B₁₂ deficiency. Vitamin B₁₂ can be replaced orally as well as by injection [52]. A study of more than 150 patients has suggested that vitamin B₁₂ therapy in deficient persons can produce significant improvement in neuropsychiatric abnormalities [48, 53]. However, another study has suggested that well-established B₁₂ deficiency may be associated with structural brain abnormalities and masked brain atrophy [54]. Clinical experience suggests that dramatic improvements after vitamin B₁₂ treatment may be less common than the literature suggests.

Hip Fracture and Nutrition

Hip fracture is a major problem in nursing homes. These fractures usually result from falls, often in conjunction with osteopenia. Older persons develop type II osteopenia, which is due to inadequate calcium intake, protein malnutrition, and vitamin D deficiency; vitamin D deficiency is especially common in nursing home residents. Institutionalized persons often get little sunlight; the skin of older persons is less capable of synthesizing cholecalciferol in the presence of ultraviolet light; the kidneys of older persons have less of the 1 -hydroxylase necessary to make the active form of vitamin D (that is, 1,25[OH]2 vitamin D); and vitamin D receptors in the gut are less functional with advancing age. An inadequate amount or effect of vitamin D can lead to poor calcium absorption and osteomalacia.

Calcium supplementation (an intake of at least 12.4 mmol/d) slows bone loss, although amounts as high as 24.8 to 37.2 mmol/d are classically recommended for older persons. Unfortunately, calcium supplementation often aggravates constipation in institutionalized persons. Chapuy and colleagues [55] showed that supplementation with 29.8 mmol of elemental calcium per day and 800 IU (20 µg) of vitamin D₃ per day in women who were 69 to 106 years old and living in nursing homes or apartment houses decreased the incidence of hip fractures by 43% and the incidence of nonvertebral fractures by 32%. In our experience, nursing home residents with calcium levels less than 2.24 mmol/L and with elevated alkaline phosphatase levels are at high risk for falls and have secondary hyperparathyroidism or vitamin D deficiency. These persons appear to be ideal candidates for calcium and vitamin D supplementation.

Diabetes Mellitus

Diabetes mellitus has many nutritional implications. Nursing home residents with diabetes mellitus tend to have more limitations than other residents [56]. Residents with diabetes mellitus are often below average weight, and therefore, in most cases, calorie-restricted diets are inappropriate. Coulston and colleagues [57] showed no advantage in glycemic control in nursing home residents with diabetes who were given an American Diabetes Association diet compared with those who were given a regular diet.

There is increasing evidence that hyperglycemia causes cognitive dysfunction and that control of glucose improves mental functioning [58]. Hyperglycemia can also result in increased pain perception [59]. Good glycemic control can be obtained in the nursing home without excessive hypoglycemia provided that physicians and staff pay careful attention to weight loss and the eating habits of these residents.

Diabetes mellitus has been associated with multiple vitamin and trace element deficiencies [60]; borderline zinc status due to decreased absorption of zinc and to hyperzincuria is especially common [61]. Zinc deficiency has been linked to poor wound healing and decreased immune function [62]. Residents with diabetes mellitus and decubitus ulcer or peripheral vascular disease ulcers may benefit from zinc replacement.

Fluid Intake and Dehydration

Dehydration is a common problem among nursing home residents that often leads to hospitalization. Even healthy older persons have decreased thirst response to dehydration owing to complex factors such as a lack of the µ-opioid drinking drive [63]. In healthy older persons, this leads to slightly higher osmolality than in younger persons [64]. Diseases, such as stroke, can further decrease the thirst response in older persons. Furthermore, nursing home residents who are confined in bed by bedrails or in a chair by physical restraints may not be able to reach the nearby water on the bedside table. Recently, we found that the application of a Posey restraint, even in healthy young persons, causes a marked decrease in their fluid intake (unpublished observation). Finally, the loss of the circadian rhythm of arginine vasopressin that occurs with aging leads to nocturia and increased fluid loss [65]. Dehydration can result in postural hypotension, constipation, and delirium. In nursing home residents, an increase in the blood urea nitrogen: creatinine ratio of greater than 20:1 is a useful indicator of incipient free water deprivation.

Hyponatremia is also not uncommon in institutionalized persons. Both low-salt diets and inadequate salt in tube-feeding solutions are important causes of hyponatremia, as is the frequent use of diuretics. The syndrome of inappropriate antidiuretic hormone is associated with many of the diseases that result in institutionalization. Several drugs result in decreased free water clearance and hyponatremia; besides thiazides, these include chlorpropamide, carbamazepine, morphine, tricyclic antidepressants, haloperidol, and phenothiazines. Atrionatriuretic factor is elevated in older persons, particularly those with congestive cardiac failure, and may play a role in the pathogenesis of hyponatremia [66]. Water retention can also lead to hyponatremia and may complicate the ability to manage diuretic-induced hyponatremia.

Physical Activity

Physical activity is an important component of nursing home care. Physical conditioning in older persons has numerous positive effects, such as slowing of the age-related changes in muscle strength, balance, aerobic conditioning, flexibility, and bone loss. In addition, Shephard [67] has suggested that many of the benefits of physical activity are nutrition-related, such as enhanced appetite, enhanced protein intake, improved bowel function (decreased constipation), and a decreased likelihood of glucose intolerance. Exercise may also enhance immune function in older persons [68].

Fiatarone and colleagues [69] studied frail nursing home residents who took part in a high-intensity exercise program over a 10-week period. Muscle strength, cross-sectional thigh muscle area, and stair-climbing ability improved in these residents. They also had an increase in total energy intake, although this was not necessarily greater than what was necessary to meet the needs of their increased energy output. Unfortunately, the exercise program had only a minimal effect on injurious falls. A meta-analysis of the FICSIT trials also failed to show that exercise affected the incidence of injurious falls [70]. Exercises specifically aimed at improving balance, on the other hand, appeared to play an important part in reducing the incidence of falls. Other studies by the Roiton group have found that exercise training enhanced insulin action, increased GLUT-4 levels [71], and increased bone mineral density [72].

Sauvage and colleagues [73] found small improvements in strength (5 to 10%) as the result of a high-intensity exercise program in the nursing home. A year-long endurance exercise program in a nursing home resulted in only minimal improvements in upper body strength and in no improvements in leg strength [74]. Two studies have suggested that a simple exercise program [75] and a walking program [76] may be as likely to be clinically beneficial in frail elderly persons as the more expensive, highintensity exercise programs.

Final Considerations

Nutritional deficiencies are commonly present in nursing home residents. In some cases, disease-associated malnutrition is the major reason for institutionalization. Nutritional problems may interfere with residents' quality of life as well as with short-term rehabilitation. They may also result in readmission to the hospital either directly (for example, in the case of dehydration) or indirectly (for example, in the case of infection). Because the consultant dietitian is a key member of the interdisciplinary team, increased funding for dietitians is needed. The key to good nutritional care is early recognition of weight loss. In residents who have weight loss (or whose albumin level is less than 35 g/L), caloric supplements (200 to 600 kcal/d) should be ordered and should be carefully sought (Table 2). If weight loss continues, the option of tube feeding should be discussed with the resident and his or her family. Careful documentation of this discussion and the outcome is essential to protect against future litigation. This approach will result in improvement in many residents.

Dr. Silver: Internal Medicine/Geriatrics, Wright Building, Suite 208, 39000 Bob Hope Drive, Rancho Mirage, CA 92270.