Protein-Energy Malnutrition



  • Protein–energy malnutrition (PEM) is present when sufficient energy and/or protein is not available to meet metabolic demands, leading to impairment in normal physiologic processes. In adults, it is highly associated with systemic inflammation.
  • Commonly seen in children in resource-limited countries, where it is estimated to contribute to 45% of all child deaths globally
  • Malnutrition in children is a major underlying factor in ~5 million preventable deaths annually, with two distinct phenotypes.
    • Marasmus (wasting syndrome): a wasting condition due to deficiency of calories and protein
    • Kwashiorkor: generalized edema and ascites, associated with low protein relative to caloric intake
  • System(s) affected: immunologic, gastrointestinal (GI), endocrine/metabolic, hematologic, musculoskeletal, integumentary, neurologic


  • Children
    • Most commonly <5 years of age
    • Prevalent sex: males = females
    • Globally, malnutrition increases morbidity and mortality from other common childhood diseases.
    • In the United States, clinical perspective and description has evolved during the past 3 decades, although older studies suggest up to 25% of all hospitalized children experienced acute PEM, and approximately 27% experience chronic food insecurity.
    • Common causes:
      • Illness—acute or chronic
      • Adverse environmental factors
      • Behavioral conditions
      • Injury
      • Congenital anomalies
  • Older patients
    • Intake reduction is one of the main causes of chronic malnutrition in the elderly.
    • Highest risk group age >75 years, affecting 5–10% of nursing home residents and up to 50% of older patients on hospital discharge
    • Increased mortality and morbidity, including pressure ulcers, infection, and cognitive status changes
    • Common causes:
      • Geriatric anorexia
      • Alterations in taste and smell
      • Hormone changes regulating gastric/intestinal motility
      • Mood alterations (dementia, depression)
  • Malnutrition may be common, but it is difficult to recognize in hospital populations.


  • Worldwide, >70 million children suffer from moderate and severe acute malnutrition.
  • Prevalence in older patients is between 29% and 61%.

Etiology and Pathophysiology

  • Inadequate dietary intake
  • Increased metabolic demands
  • Increased nutrient losses

Risk Factors

  • Conditions that predispose the patient to cachexia also increase the risk of PEM.
  • Starvation-related malnutrition
    • Prolonged and severe reduction of intake
    • Anorexia nervosa
  • Chronic inflammatory states (rheumatoid arthritis, chronic cardiac or lung disease, and cancer)
  • Metabolic disorders (diabetes, hyperthyroidism)
  • Malabsorptive and maldigestive states (celiac disease and pancreatic insufficiency)
  • Protein-losing enteropathy, liver cirrhosis, chronic kidney disease, nephrotic syndrome, enteric fistulas
  • Marked inflammatory conditions: acute disease, fever, infection, trauma, burns, closed head injury
  • Other states in which caloric requirements are increased: pregnancy and lactation, childhood growth and development
  • Functional, financial, and social factors may limit access to an adequate diet.
  • Elders with delirium, dementia, or depression or long periods spent NPO or with prolonged hospitalization are at high risk for malnutrition.
  • Extreme high- or low-BMI individuals are also at increased risk.
  • Malnutrition can occur in healthy weight or overweight individuals. BMI can be a tool in the identification of chronic malnutrition in patients but should not be used as a sole method of screening or diagnosis.
  • Cirrhotic patients: PEM is one of the most common complications in liver cirrhosis and is associated with an increased risk of variceal bleeding, ascites, hepatic encephalopathy, and hepatorenal syndrome.

General Prevention

  • Observation and recording of patients’ nutritional intake and BMI
  • In children, routine record of anthropomorphic measurements and developmental milestones
  • Early recognition of increased nutritional requirements during stress, infection, and other medical illness
  • Emphasis on food security and nutritional education

Commonly Associated Conditions

  • Infection: weakened immune system, predisposing to bacterial, viral, and parasitic infections
  • Electrolyte disturbances: loss of cellular integrity, diminished transmembrane pump activity, renal dysfunction
  • Hypoglycemia: decreased glycogen stores, increased glucose use (as in infection or trauma)
  • Micronutrient deficiencies: vitamins, including B complex, folic acid, iron, magnesium (1)
  • Wounds: pressure ulcers in older patients (increased incidence if reduced mobility)

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