INVOLUNTARY WEIGHT LOSS

ESSENTIAL INQUIRIES

Age.
Caloric intake.
Fever.
Change in bowel habits.
Secondary confirmation (eg, changes in clothingsize).
Substance use.
Age-appropriate cancer screening history.

General Considerations

Body weight is determined by a person’s caloric intake, absorptive capacity, metabolic rate, and energy losses. The metabolic rate can be affected by a multitude of medical conditions through the release of various cytokines such as cachectin and interleukins. Body weight normally peaks by the fifth or sixth decade and then gradually declines at a rate of 1–2 kg per decade. In NHANES II, a national survey of community-dwelling elders (age 50–80 years), recent involuntary weight loss (> 5% usual body weight) was reported by 7% of respondents, and this was associated with a 24% higher mortality.

Etiology

Involuntary weight loss is regarded as clinically significant when it exceeds 5% or more of usual body weight over a 6- to 12-month period and often indicates serious physical or psychological illness. Physical causes are usually evident during the initial evaluation. Cancer (about 30%), gastrointestinal disorders (about 15%), and dementia or depression (about 15%) are the most common causes. When an adequately nourished-appearing patient complains of weight loss, inquiry should be made about exact weight changes (with approximate dates) and about changes in clothing size. Family members can provide confirmation of weight loss, as can old documents such as driver’s licenses. A mild, gradual weight loss occurs in some older individuals. It is due to changes in body composition, including loss of height and lean body mass and lower basal metabolic rate, leading to decreased energy requirements. However, rapid involuntary weight loss is predictive of morbidity and mortality in any population. In addition to various disease states, causes in older individuals include loss of teeth and consequent difficulty with chewing, alcoholism, and social isolation.

Clinical Findings

Once the weight loss is established, the history, medication profile, physical examination, and conventional laboratory and radiologic investigations (such as complete blood count, serologic tests including HIV, thyroid-stimulating hormone [TSH] level, urinalysis, fecal occult blood test, chest radiography, and upper gastrointestinal series) usually reveal the cause. When these tests are normal, the second phase of evaluation should focus on more definitive gastrointestinal investigation (eg, tests for malabsorption; endoscopy) and cancer screening (eg, Papanicolaou smear, mammography, prostate specific antigen [PSA]). 

If the initial evaluation is unrevealing, follow-up is preferable to further diagnostic testing. Death at 2-year followup was not nearly as high in patients with unexplained involuntary weight loss (8%) as in those with weight loss due to malignant (79%) and established nonmalignant diseases (19%). Psychiatric consultation should be considered when there is evidence of depression, dementia, anorexia nervosa, or other emotional problems. Ultimately, in approximately 15–25% of cases, no cause for the weight loss can be found.

Differential Diagnosis

Malignancy, gastrointestinal disorders (eg, malabsorption, pancreatic insufficiency), dementia, depression, anorexia nervosa, hyperthyroidism, alcoholism, and social isolation are all established causes. “Meals on Wheels” is a useful mnemonic for remembering the common treatable causes of involuntary weight loss in the elderly (see box below).

Meals on Wheels: A Mnemonic
for Common Treatable
Causes of Unintentional
Weight Loss in the Elderly.

Medication effects
Emotional problems, especially depression
Anorexia tardive (nervosa), alcoholism
Late-life paranoia
Swallowing disorders
Oral factors (eg, poorly fitting dentures, cavities)
No money
Wandering and other dementia-related behaviors
Hyperthyroidism, hypothyroidism, hyperparathyroidism, hypoadrenalism
Enteric problems (eg, malabsorption)
Eating problems (eg, inability to feed self)
Low-salt, low-cholesterol diets
Social problems (eg, isolation, inability to obtain preferred foods), gallstones

Treatment

Weight stabilization occurs in most surviving patients with both established and unknown causes of weight loss through treatment of the underlying disorder and caloric supplementation. Nutrient intake goals are established in relation to the severity of weight loss, in general ranging from 30 to 40 kcal/kg/d. In order of preference, route of administration options include oral, temporary nasojejunal tube, or percutaneous gastric or jejunal tube. Parenteral nutrition is reserved for patients with serious associated problems. A variety of pharmacologic agents have been proposed for the treatment of weight loss. These can be categorized into appetite stimulants (corticosteroids, progestational agents, dronabinol, and serotonin antagonists); anabolic agents (growth hormone and testosterone derivatives); and anticatabolic agents (omega-3 fatty acids, pentoxifylline, hydrazine sulfate,
and thalidomide).

When to Refer

• Weight loss caused by malabsorption.
• Persistent nutritional deficiencies despite adequate supplementation.
• Weight loss as a result of anorexia or bulimia.

When to Admit

• Severe protein-energy malnutrition, including the syndromes of kwashiorkor and marasmus.
• Vitamin deficiency syndromes.
• Cachexia with anticipated progressive weight loss secondary to unmanageable psychiatric disease.
• To carefully manage electrolyte and fluid replacement in protein-energy malnutrition and avoid “re-feeding syndrome.”