Protein–Energy Malnutrition

Essentials of Diagnosis

• Decreased intake of energy or protein, increased nutrient losses, or increased nutrient requirements

• Kwashiorkor: caused by protein deficiency

• Marasmus: caused by combined protein and energy deficiency

• Protein loss correlates with weight loss: 35–40% total body weight loss is usually fatal

General Considerations

• Results from a relative or absolute deficiency of energy and protein

• May be primary, due to inadequate food intake, or secondary, as a result of other illness

• For most developing nations, primary protein–energy malnutrition remains among the most significant health problems

• It occurs in two distinct syndromes

  • Kwashiorkor

    • Caused by a deficiency of protein in the presence of adequate energy

    • Typically seen in weaning infants at the birth of a sibling in areas where foods containing protein are insufficient

  • Marasmus

    • Caused by combined protein and energy deficiency

    • Seen where adequate quantities of food are simply not available

• In industrialized societies, protein–energy malnutrition is most often secondary to other diseases

  • Kwashiorkor-like secondary protein–energy malnutrition occurs primarily in association with hypermetabolic acute illnesses such as

    • Trauma

    • Burns

    • Sepsis

  • Marasmus-like secondary protein–energy malnutrition typically results from chronic diseases such as

    • Chronic obstructive pulmonary disease (COPD)

    • Heart failure

    • Cancer

    • AIDS

  • In both syndromes, protein–energy malnutrition is caused either by decreased intake of energy and protein or by increased nutrient losses related to the underlying illness

• Every organ system affected

• Loss of body weight, adipose stores, and skeletal muscle mass

• Loss of protein from skeletal muscle and internal organs is usually proportionate to weight loss

• Hepatic synthesis of serum proteins decreases, and depressed levels of circulating proteins are observed

• Cardiac output and contractility are decreased

• Respiratory function

  • Affected primarily by weakness and atrophy of the muscles of respiration

  • Vital capacity and tidal volume are depressed

  • Mucociliary clearance is abnormal

• Gastrointestinal tract

  • Affected by mucosal atrophy and loss of villi of the small intestine, resulting in malabsorption

  • Intestinal disaccharidase deficiency and mild pancreatic insufficiency also occur

• Changes in immunologic function are among the most important changes

  • T lymphocyte number and function are depressed

  • Changes in B cell function are more variable

  • Impaired complement activity, granulocyte function, and anatomic barriers to infection are noted

  • Wound healing is poor

• Dependent edema, ascites, or anasarca may develop

• Serum albumin may be normal or slightly decreased, rarely decreasing to < 2.8 g/dL (28 g/L)

• The serum protein level, however, typically declines and the serum albumin is often < 2.8 g/dL (28 g/L)

• ECG may show decreased voltage and a rightward axis shift

• Severe protein–energy undernutrition

  • Initial efforts

    • Should be directed at correcting fluid and electrolyte abnormalities and infections

    • Of particular concern are depletion of potassium, magnesium, and calcium and acid-base abnormalities

  • Second phase of treatment

    • Directed at repletion of protein, energy, and micronutrients

    • Started with modest quantities of protein and calories calculated based on the patient's actual body weight

    • Adult patients are given 1 g/kg of protein and 30 kcal/kg of calories

    • Concomitant administration of vitamins and minerals is obligatory

    • Either the enteral or parenteral route can be used, although the former is preferable

    • Enteral fat and lactose are withheld initially

• Patients with less severe protein–calorie undernutrition

  • Can be given calories and protein simultaneously with the correction of fluid and electrolyte abnormalities

  • Similar quantities of protein and calories are recommended for initial treatment

  • In adults, both calories and protein are advanced as tolerated, adults to 1.5 g/kg/day of protein and 40 kcal/kg/day of calories

Follow-Up

• Patients require close monitoring

Complications

• Refeeding edema

  • A benign condition to be differentiated from heart failure

  • Changes in renal sodium reabsorption and poor skin and blood vessel integrity result in the development of dependent edema without other signs of heart disease

• During refeeding, circulating potassium, magnesium, phosphorus, and glucose move intracellularly and can result in low serum levels of each

• The administration of water and sodium with carbohydrate refeeding can result in heart failure in persons with depressed cardiac function

• Enteral refeeding can lead to malabsorption and diarrhea due to abnormalities in the gastrointestinal tract

Prevention

• The prevention and early detection of protein–energy malnutrition in hospitalized patients require awareness of its risk factors and early symptoms and signs

• Patients at risk require formal assessment of nutritional status and close observation of dietary intake, body weight, and nutritional requirements during the hospital stay

Prognosis

• Weight losses of 5–10% are usually tolerated without loss of physiologic function

• Weight losses of 35–40% of body weight usually result in death