OVERVIEW

What is protein-energy malnutrition?

Protein-energy malnutrition (PEM) is a condition caused by the body's inability to obtain sufficient protein and energy. It is commonly seen in children and the elderly. The inability to access adequate healthy food is a frequent cause.

However, with improvements in living conditions, it is now more often associated with poor nutrient absorption due to physical illnesses, such as digestive system abnormalities (anatomical or functional), malabsorption disorders, prolonged fever, various acute or chronic infectious diseases, and chronic wasting diseases (e.g., cancer). These conditions can lead to increased catabolism, reduced food intake, and metabolic disorders. Congenital factors like premature birth, multiple births, or intrauterine malnutrition may also contribute to postnatal malnutrition.

Can protein-energy malnutrition be cured?

Yes, it can be cured by gradually replenishing the nutrients the body needs. However, if there are underlying malignant or uncontrolled diseases, protein-energy malnutrition may be difficult to improve.

Does protein-energy malnutrition have sequelae?

For children, long-term malnutrition may lead to developmental delays that may not fully recover even after treatment.

Protein-energy malnutrition during infancy and early childhood can affect not only physical growth but also brain development, often resulting in cognitive impairments.

Is protein-energy malnutrition common?

It is common in economically disadvantaged areas, primarily due to limited access to healthy food or diets with insufficient protein content.

SYMPTOMS

What are the manifestations of protein-energy malnutrition?

Globally, severe protein-energy malnutrition (PEM) is a leading cause of death in children under 5 years of age. Severe PEM can cause one of two classic syndromes: marasmus (wasting syndrome) or kwashiorkor, or a combination of both.

PEM can be classified into different clinical subtypes based on the presence or absence of edema. Traditionally, PEM without edema is called marasmus, while PEM with edema is called kwashiorkor:

• Marasmus: Marasmus (i.e., PEM without edema) is characterized by muscle wasting and depletion of body fat stores. This is the most common form of PEM, caused by insufficient intake of all nutrients, particularly dietary energy sources (total calories). Typically, children with marasmus may experience severe constipation and exhibit extreme hunger once refeeding begins. Physical examination findings include:

  • Weight and height for age below the normal range;
  • Prominent head and dull eyes;
  • Emaciated and weak appearance, with emotional irritability and restlessness;
  • Bradycardia, hypotension, and hypothermia;
  • Thin and dry skin;
  • Atrophied arms, thighs, and buttocks, with loose skin folds due to loss of subcutaneous fat;
  • Fine, sparse hair that is easily plucked.

• Kwashiorkor: Kwashiorkor (i.e., PEM with edema) is characterized by significant muscle wasting with normal or increased body fat and the presence of peripheral edema (generalized edema). Edema is the defining feature for diagnosis. Insufficient protein and energy intake may contribute to the clinical features of kwashiorkor, but its pathogenesis is not fully understood. Anorexia is almost universal. Physical examination findings include:

  • Normal or near-normal weight for age;
  • Generalized edema (severe widespread edema);
  • Pitting edema in the lower limbs, presacral area, genitals, and periorbital region;
  • Apathy and lethargy;
  • Round, protruding cheeks ("moon face");
  • Pouting mouth;
  • Dry, atrophic, and easily peeling skin, with areas of hyperkeratosis and hyperpigmentation;
  • Dry, dull, hypopigmented hair that is easily plucked or falls out;
  • Hepatomegaly (due to fatty liver infiltration);
  • Abdominal distension with dilated intestinal loops but no ascites;
  • Hypothermia.

• Marasmic-kwashiorkor: Marasmic-kwashiorkor (edematous malnutrition) may occur in children with insufficient intake of various nutrients and can be triggered by common childhood infectious diseases. Children with marasmic-kwashiorkor often exhibit anorexia, dermatitis, and sometimes neurological abnormalities (depression and emotional flatness) and hepatic steatosis.

Among these, when a patient transitions from marasmus to marasmic-kwashiorkor, the morbidity and mortality rates of complications are relatively high.

CAUSES

What are the causes of protein-energy malnutrition? Which populations are most commonly affected?

Insufficient protein or inadequate energy intake from food. In simple terms, it means not eating enough or consuming enough calories. Alternatively, it may involve eating enough in quantity but lacking high-quality protein sources such as meat, eggs, or dairy.

With improvements in living conditions, it is now more commonly caused by medical conditions that impair nutrient absorption, such as digestive system abnormalities (anatomical or functional), malabsorption disorders, prolonged fever, various acute or chronic infectious diseases, and chronic wasting diseases (e.g., cancer). These conditions can lead to increased catabolism, reduced food intake, and metabolic disorders. Congenital factors like premature birth, multiple births, or intrauterine malnutrition can also contribute to postnatal malnutrition.

Therefore, protein-energy malnutrition is not only prevalent among individuals with the aforementioned conditions but also occurs in children, elderly individuals, pregnant women, those with anorexia, and picky or selective eaters from economically disadvantaged families.

What other diseases can protein-energy malnutrition lead to?

Patients with protein-energy malnutrition may develop complications such as micronutrient deficiencies, vitamin A deficiency, vitamin D deficiency, iron-deficiency anemia, hypoproteinemia, and hypoglycemia, which can be life-threatening in severe cases. Additionally, malnutrition increases susceptibility to infections in various organs. Such individuals often have compromised immune function, making them more prone to infections, which in turn exacerbate malnutrition. Specific manifestations include:

• Vitamin A deficiency may present as reduced vision, difficulty seeing in dim light, and dry eyes.

• Vitamin D deficiency can lead to abnormal bone growth and development, resulting in short stature, a square-shaped head, and prominent rib beading.

• Anemia may manifest as pale skin, lips, and nail beds, along with fatigue.

• Hypoproteinemia can cause skin edema, ascites, and hardened skin with reduced elasticity.

DIAGNOSIS

What tests are needed to diagnose protein-energy malnutrition?

Review the patient's dietary intake (preferably have the patient keep a detailed food diary), and arrange blood tests, biochemistry, abdominal ultrasound, thyroid function tests, stool analysis, etc., as appropriate.

What is the purpose of the tests for patients with protein-energy malnutrition?

• Reviewing the patient's diet: Assess whether the food provides sufficient energy and protein for the body's needs.

• Blood tests and biochemistry panel: Evaluate liver and kidney function, assess for anemia, hypoproteinemia, electrolyte imbalances, metabolic acidosis/alkalosis, and determine the type of anemia, electrolyte status, and dehydration.

• Abdominal ultrasound: Check for ascites, tumors, or other abnormalities in abdominal organs.

• Thyroid function and growth hormone tests: Determine if there are abnormalities in the endocrine system.

• Stool analysis: Check for parasites, chronic gastrointestinal bleeding, or other conditions.

TREATMENT

Which department should I visit for protein-energy malnutrition?

Adults are advised to go to the Nutrition Department or Gastroenterology Department. For children, in addition to the Nutrition Department, they can also visit the Pediatrics Department or Child Health Department.

How is protein-energy malnutrition treated?

First, assess the condition. The WHO has established classification criteria for moderate or severe malnutrition in children. These criteria consider factors such as the degree of wasting and stunting, as well as the presence of edema. A child's height/weight and age/height are expressed using Z-scores. The definitions of wasting and stunting are as follows (these diagnoses may coexist):

• Wasting (indicating acute malnutrition):

  • Moderate wasting: Weight/height Z-score less than -2 to -3;

  • Severe wasting: Weight/height Z-score less than -3;

• Stunting (indicating chronic malnutrition):

  • Moderate stunting: Height or length Z-score less than -2 to -3;

  • Severe stunting: Height or length Z-score less than -3.

• Malnutrition:

  • Moderate malnutrition: Moderate wasting or stunting;

  • Severe malnutrition: Severe wasting, severe stunting, or edematous malnutrition.

The WHO recommends using these definitions for severe wasting or bilateral edema as criteria for hospitalization in cases of severe acute malnutrition.

Next, gradually replenish nutrients. When the body has been in a state of long-term malnutrition, nutrients should not be fully supplied all at once. Instead, nutritional intake should be increased step by step, and food combinations should be improved.

If there is impaired digestion or absorption, enteral nutrition or parenteral intravenous nutrition may be considered, along with supplementation of trace elements and vitamins.

What should protein-energy malnutrition patients pay attention to during hospitalization?

Follow the doctor's advice and maintain regular eating habits. Ensure proper food variety and balanced nutrient intake.

Is follow-up necessary after discharge for protein-energy malnutrition treatment?

Yes, follow-up is required. For children, regular check-ups and developmental assessments are necessary. If there are delays in motor function or cognition, specialized training and rehabilitation therapy should be conducted under medical guidance.

Can protein-energy malnutrition recur after treatment?

If malnutrition is caused by a disease that impairs nutrient absorption, recurrence is possible if the underlying cause is not addressed or poor dietary habits are not corrected. (For example, a vegetarian without any disease but with a picky eating habit may experience recurrent malnutrition if the habit persists.)

DIET & LIFESTYLE

What should patients with protein-energy malnutrition pay attention to in their diet?

Pay attention to the quantity and combination of food, supplement high-quality protein (including meat, eggs, milk, fish, and soy products) and fats. At the same time, consume sufficient vegetables and fruits. Food variety should be diverse. If outdoor activities are limited, supplement with vitamin D.

If it is part of a treatment plan, meals should be prepared under the guidance of a nutritionist. The adjustment speed of calories, protein, and fat intake varies from person to person and should not be too fast to avoid indigestion.

What should patients with protein-energy malnutrition pay attention to in daily life?

• Infants and young children should undergo regular physical examinations to assess height, weight, head circumference, and developmental status. If growth retardation or developmental delays are detected, the cause should be identified promptly.

• For the elderly or patients with chronic diseases, regular physical examinations to assess nutritional status are also necessary. Early detection of malnutrition signals allows for timely correction.

PREVENTION

Can Protein-Energy Malnutrition Be Prevented?

Yes, it can.

• During infancy, prioritize breastfeeding when possible. Nursing mothers should supplement with protein and calcium. Breastfeeding should continue for at least one year, and up to two years if conditions allow.

• If breast milk is insufficient, supplement with infant formula instead of rice porridge or cow's milk. Children under one year old should not consume cow's milk. For infants under six months, their diet should consist entirely of milk—no additional water, sugar water, or broth is needed. During the complementary feeding stage, focus on iron-rich foods such as lean meat, liver, and iron-fortified rice cereal, which is better than plain rice porridge.

• Introduce complementary foods scientifically and appropriately, ensuring a diverse variety of foods.

• Children under two years old require a daily intake of 400 IU (10 µg) of vitamin D. If outdoor activity is limited, older children may also need vitamin D supplementation.

• Schedule regular pediatric physical examinations, including weight, height, and developmental assessments.

• Adults with eating disorders, wasting diseases, or conditions like cancer should seek guidance from a nutritionist promptly. Evaluating their condition and implementing appropriate nutritional measures can prevent malnutrition.