What is the correct term for protein malnutrition? Clarifying PEM and Its Forms

October 25, 2025 •

3 min read

According to the World Health Organization, nearly half of all deaths in children under five are linked to undernutrition. Given the severity of this issue, understanding exactly what is the correct term for protein malnutrition is crucial for proper diagnosis and treatment. The most precise medical term is not a simple protein deficiency but rather Protein-Energy Malnutrition (PEM) or Protein-Energy Undernutrition (PEU).

Quick Summary

The medically accurate term for protein malnutrition is Protein-Energy Malnutrition (PEM) or undernutrition (PEU). It encompasses severe deficiency conditions like kwashiorkor, which is marked by edema, and marasmus, characterized by severe wasting.

Key Points

Correct Term: The precise medical term for protein malnutrition is Protein-Energy Malnutrition (PEM) or undernutrition (PEU), as it almost always involves a deficiency of both protein and calories.
Kwashiorkor: A form of severe PEM caused primarily by protein deficiency, leading to edema (swelling) and a distended belly, even if calorie intake is adequate.
Marasmus: A severe PEM resulting from a general deficiency of both protein and calories, causing extreme muscle and fat wasting without edema.
Underlying Causes: PEM is driven by factors including poverty, food insecurity, chronic infections, poor weaning practices, and other medical conditions.
Treatment: Management involves a staged approach: stabilizing life-threatening issues, gradual nutritional rehabilitation, and long-term recovery support.
Long-term Effects: Untreated PEM can lead to stunted growth, weakened immunity, and permanent cognitive impairment.

Clarifying the Correct Term for Protein Malnutrition

While "protein malnutrition" is commonly used, the more accurate medical term is Protein-Energy Malnutrition (PEM), also called Protein-Energy Undernutrition (PEU). This is because a lack of protein is usually accompanied by a deficiency in calories and other nutrients. PEM covers a range of conditions with varying severity and features.

The Two Main Forms of Severe Protein-Energy Malnutrition

Severe PEM primarily manifests in two distinct forms, particularly in children:

Kwashiorkor (Wet Protein-Energy Malnutrition): Caused by severe protein deficiency, often with sufficient calories, leading to edema (swelling) in areas like the feet, face, and belly. Other signs include an enlarged liver and skin/hair changes. It's commonly seen in children transitioning from breastfeeding to a high-carbohydrate, low-protein diet.
Marasmus (Dry Protein-Energy Malnutrition): Results from severe deficiencies in both protein and calories. It causes extreme wasting of muscle and fat, making the individual severely underweight with loose, wrinkled skin. Unlike kwashiorkor, edema is typically absent.

The Overlap: Marasmic Kwashiorkor

In some cases, individuals show symptoms of both kwashiorkor and marasmus, which is known as Marasmic Kwashiorkor. This is the most severe type of PEM, combining extreme wasting and edema.

Causes of Protein-Energy Malnutrition

PEM stems from multiple factors, including socioeconomic conditions, environment, and health status. It can be primary, due to insufficient food intake, or secondary, caused by diseases affecting nutrient absorption or increasing needs.

Major causes include:

Poverty and Food Insecurity: A leading global cause, especially in children in developing regions.
Chronic Illnesses and Infections: Conditions like HIV/AIDS and cancer can increase nutrient demands and hinder appetite or absorption.
Inadequate Weaning Practices: Weaning onto low-protein, high-carbohydrate diets can lead to kwashiorkor.
Eating Disorders: Anorexia nervosa is one example.
Aging: Elderly individuals are at higher risk due to decreased appetite and health issues.

Recognizing the Symptoms

Symptoms of PEM vary with type and severity. Key signs include wasting and edema, along with:

Behavioral Changes: Common symptoms include apathy and irritability, particularly in children.
Impaired Growth: Stunted growth and failure to gain weight indicate chronic PEM.
Hair and Skin Changes: Hair may become thin and discolored; skin can be dry and prone to sores.
Weakened Immune System: PEM compromises the immune system, increasing infection risk.
Gastrointestinal Issues: Diarrhea and poor appetite are frequent.

Kwashiorkor vs. Marasmus: A Comparative Look

The table below highlights the main differences between severe kwashiorkor and marasmus.


Feature	Kwashiorkor	Marasmus
Primary Deficiency	Protein (often with adequate calories)	Both Protein and Calories
Edema (Swelling)	Present (ankles, feet, face, belly)	Absent
Muscle Wasting	Can be present, but may be masked by fluid retention	Severe, prominent wasting of muscle and fat
Weight Loss	Variable, can be masked by edema	Severe weight loss, very low weight-for-height
Appearance	Bloated or distended belly, "moon face"	Emaciated, skeletal appearance with loose skin
Skin & Hair	Flaky, peeling skin, hair changes (discoloration, thinness)	Dry, thin, and inelastic skin; dry hair
Associated Condition	Weaning onto starchy, low-protein diet	Prolonged starvation or severe poverty

Diagnosis and Treatment

Diagnosing PEM involves physical examination, dietary history, and measurements. Blood tests can assess protein levels and other markers to determine severity.

Treatment follows a multi-stage approach to prevent complications.

Stabilization: Addressing immediate threats like low blood sugar, low body temperature, dehydration, and infections is the first step.
Nutritional Rehabilitation: Gradual refeeding with small, frequent meals helps restore nutrients slowly.
Long-term Recovery: The diet is adjusted to provide adequate nutrients. Support is provided to prevent recurrence.

Prevention is Key

Preventing PEM requires addressing its root causes through various strategies:

Nutritional Education: Teaching about healthy diets, breastfeeding, and weaning is crucial.
Food Security: Ensuring access to nutritious food is vital, especially in vulnerable areas.
Public Health Measures: Access to clean water, sanitation, and immunizations helps reduce infections that worsen malnutrition.
Dietary Variety: Promoting varied diets with sufficient protein sources ensures essential nutrient intake.

For more in-depth information, the World Health Organization (WHO) provides global guidelines on addressing malnutrition and related health issues. WHO: Malnutrition

Conclusion

The correct medical term for protein malnutrition is Protein-Energy Malnutrition (PEM), a broader condition encompassing severe forms like kwashiorkor and marasmus. Understanding this terminology and the underlying causes is essential for effective prevention and treatment. Addressing PEM requires a comprehensive approach considering energy intake, micronutrients, and socioeconomic factors to promote long-term health.

Frequently Asked Questions

The main difference is the type of deficiency and resulting symptoms. Kwashiorkor results from severe protein deficiency with edema (swelling), while marasmus is a deficiency of both protein and calories, resulting in extreme wasting without edema.

Yes, while PEM is often associated with children in developing nations, it can also affect adults, particularly the elderly, those with chronic illnesses, or individuals with eating disorders.

Initial signs of kwashiorkor include fatigue, irritability, and growth failure, followed by the characteristic development of edema (swelling), a distended abdomen, and changes to the skin and hair.

Diagnosis of PEM is based on a physical examination, assessment of dietary history, and measurements of height and weight. Blood tests to check for low albumin and other deficiencies are also used to determine the severity.

Treatment is a delicate process to avoid refeeding syndrome. It begins with stabilization of fluid and electrolyte imbalances, followed by a slow, gradual reintroduction of nutrients. Infections are also treated with antibiotics.

Long-term consequences of PEM in children can include impaired physical and mental development, stunted growth, a weakened immune system, and increased susceptibility to chronic diseases later in life.

Prevention of PEM involves improving food security, promoting nutritional education, encouraging proper breastfeeding and weaning practices, and addressing underlying medical conditions or poverty that contribute to malnutrition.