Protein-Energy Malnutrition

Updated: Mar 11, 2019
  • Author: Hadi Atassi, DO; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
  • Print


The World Health Organization (WHO) defines malnutrition as "the cellular imbalance between the supply of nutrients and energy and the body's demand for them to ensure growth, maintenance, and specific functions." [1]  The term protein-energy malnutrition (PEM) applies to a group of related disorders that include marasmus, kwashiorkor (see the images below), and intermediate states of marasmus-kwashiorkor.

Children with kwashiorkor have nutritional edema and metabolic disturbances, including hypoalbuminemia and hepatic steatosis, whereas marasmus is characterized by severe wasting. [2]  Studies suggest that marasmus represents an adaptive response to starvation, whereas kwashiorkor represents a maladaptive response to starvation. Children may also present with a mixed picture of marasmus and kwashiorkor or with milder forms of malnutrition. 

This photograph shows children and a nurse attenda This photograph shows children and a nurse attendant at a Nigerian orphanage in the late 1960s. Note that four of the children have gray-blond hair, a symptom of the protein-deficiency disease kwashiorkor. Image courtesy of Dr Lyle Conrad and the Centers for Disease Control and Prevention Public Health Image Library.
This late 1960s photograph shows a seated, listles This late 1960s photograph shows a seated, listless child who was among many individuals found with kwashiorkor in Nigerian relief camps during the Nigerian-Biafran war. Kwashiorkor is a disease that develops due to a severe dietary protein deficiency. This child, whose diet fit such a deficiency profile, presented with symptoms including edema of the legs and feet; light-colored, thinning hair; anemia; a pot-belly; and shiny skin. Image courtesy of Dr Lyle Conrad and the Centers for Disease Control and Prevention Public Health Image Library.

Protein-energry malnutition is a global issue, seen primarily in resource-limited countries. Overall, malnutrition has decreased worldwide, but the rates vary by region. For example, Asia has seen declines in this condition, whereas there has been a continued increase in African nations. [3]

Malnutrition can be classified as acute versus chronic. Features of chronic malnutrition include stunted growth, mental apathy, developmental delay, and poor weight gain. [4, 5]  Acute malnutition manifests itself in two major forms: marasums (the most common form) and kwashiorkor, although some patients' condition may manifest as a combination of both forms (marasmic kwashiorkor).

Children with marasmus are often low weight-for-height and have a reduced mid-upper arm circumference, as well as a head that appears large relative to the rest of their body. Other findings include dry skin, thin hair, and irritability. Kwashiorkor is characterized by peripheral pitting edema, as well as "moon facies," hepatomegaly, and a pursed mouth.



In general, marasmus occurs when there is an insufficient energy intake to match the body's requirements. As a result, the body draws on its own stores, resulting in emaciation. In kwashiorkor, adequate carbohydrate consumption and decreased protein intake lead to decreased synthesis of visceral proteins. The resulting hypoalbuminemia contributes to extravascular fluid accumulation. Impaired synthesis of B-lipoprotein produces a fatty liver.

Protein-energy malnutrition also involves an inadequate intake of many essential nutrients. Low serum levels of zinc have been implicated as the cause of skin ulceration in many patients. In a 1979 study of 42 children with marasmus, Golden and Golden found that only those with low serum levels of zinc developed skin ulceration. [6] Serum zinc levels correlated closely with the presence of edema, stunted growth, and severe wasting. The classic "mosaic skin" and "flaky paint" dermatosis of kwashiorkor bears considerable resemblance to the skin changes of acrodermatitis enteropathica, the dermatosis of zinc deficiency.

In 2007, Lin et al stated that "a prospective assessment of food and nutrient intake in a population of Malawian children at risk for kwashiorkor" found "no association between the development of kwashiorkor and the consumption of any food or nutrient." [7]

Marasmus and kwashiorkor can both be associated with impaired glucose clearance that relates to dysfunction of pancreatic beta-cells. [8] In utero, plastic mechanisms appear to operate, adjusting metabolic physiology and adapting postnatal undernutrition and malnutrition to define whether marasmus and kwashiorkor will develop. [9]

A 2013 report from Texas noted an 18-month-old infant with type 1 glutaric acidemia who had extensive desquamative plaques, generalized nonpitting edema, and red-tinged sparse hair, with low levels of zinc, alkaline phosphatase, albumin, and iron. [10] This patient had a variation of kwashiorkor, and the authors suggested that it be termed acrodermatitis dysmetabolica. [10]

For complex reasons, sickle cell anemia can predispose sufferers to protein malnutrition. [11]

Protein-energy malnutrition ramps up arginase activity in macrophages and monocytes. [12]

Derangements to the gut microbiome in undernourished hosts also appear to play a role in the pathophysiology that results in persistent growth impairment in children. [13]



Worldwide, the most common cause of malnutrition is inadequate food intake. Preschool-aged children in developing countries are often at risk for malnutrition because of their dependence on others for food, increased protein and energy requirements, immature immune systems causing a greater susceptibility to infection, and exposure to nonhygienic conditions.

Another significant factor is ineffective weaning secondary to ignorance, poor hygiene, economic factors, and cultural factors. The prognosis is worse when protein-energy malnutrition occurs with human immunodeficiency virus (HIV) infection. Gastrointestinal infections can and often do precipitate clinical protein-energy malnutrition because of associated diarrhea, anorexia, vomiting, increased metabolic needs, and decreased intestinal absorption. In addition, parasitic infections play a major role in many parts of the world.

In developed nations, inadequate food intake is a less common cause of malnutrition than that caused by decreased absorption or abnormal metabolism. Thus, diseases, such as cystic fibrosis, chronic renal failure, childhood malignancies, congenital heart disease, and neuromuscular diseases contribute to malnutrition in developed countries. Fad diets, inappropriate management of food allergies, and psychiatric diseases (eg, anorexia nervosa) can also lead to severe protein-energy malnutrition.

Populations in both acute- and long-term facilities are at risk for clinically significant involuntary weight loss (IWL) that can result in protein-energy malnutrition. IWL is defined as a loss of 4.5 kg or greater than 5% of the usual body weight over a period of 6-12 months. Protein-energy malnutrition occurs when weight loss of greater than 10% of normal body weight occurs.

Elderly patients are often at risk for protein-energy malnutrition because of inadequate nutrition, which has been determined to be a common comorbid factor for increased morbidity and mortality in elderly burn victims. [14]

Anorexia of aging, defined as the loss of appetite and/or decreased food intake in late life, is used to describe multifaceted clinical conditions that are common among frail older persons but not easily grouped into specific diseases or syndrome categories. Common causes of resulting malnutrition include decreased appetite, dependency on help for eating, impaired cognition and/or communication, poor positioning, frequent acute illnesses with gastrointestinal losses, medications that decrease appetite or increase nutrient losses, polypharmacy, decreased thirst response, decreased ability to concentrate urine, intentional fluid restriction due to fear of incontinence or choking if dysphagic, psychosocial factors such as isolation and depression, monotony of diet, higher nutrient density requirements, and other demands of age, illness, and disease on the body. [15]

Protein-energy malnutrition is one of the most common complications in liver cirrhosis patients, with reported rates of 25.1% to 65.5%.

Patients on long-term hemodialysis also may develop protein-energy malnutrition; this is associated with increased morbidity and mortality.

Patients with squamous cell carcinoma of the esophagus are at risk for protein-energy malnutrition.

Bariatric surgery can be associated with iatrogenic kwashiorkor. [16, 17]



United States data

Protein-energy malnutrition is the most common form of nutritional deficiency among patients who are hospitalized in the United States. Up to half of all patients admitted to the hospital have malnutrition to some degree. In a survey of a large children's hospital, the prevalence of acute and chronic protein-energy malnutrition was more than 50%.

Protein-energy malnutrition is very much a disease that occurs in 21st century, even in the United States and other developed nations. [18, 19]  The case of an 8-month-old child with kwashiorkor in suburban Detroit, Michigan, was reported in 2010, [20]  and additional US cases of kwashiorkor have been noted, such as that of a baby in 2013 with a clinical picture imitating Stevens-Johnson syndrome but who in fact had kwashiorkor. [21] Babies solely fed on rice milk can also develop kwashiorkor.

In a survey focusing on low-income areas of the United States, 22-35% of children aged 2-6 years were below the 15th percentile for weight. Another survey showed that 11% of children in low-income areas had height-for-age measurements below the 5th percentile. Poor growth is seen in 10% of children in rural populations.

In hospitalized elderly persons, up to 55% are undernourished. Up to 85% of institutionalized elderly persons are undernourished. Studies have shown that as many as 50% have vitamin and mineral intake that is less than the recommended dietary allowance, and up to 30% of elderly persons have below-normal levels of vitamins and minerals.

International data

In 2000, the World Health Organization (WHO) estimated that malnourished children numbered 181.9 million (32%) in developing countries. [22]  In addition, approximately 149.6 million children younger than 5 years were malnourished when measured in terms of weight for age. In south central Asia and eastern Africa, about half the children had growth retardation due to protein-energy malnutrition. This figure was five times the prevalence in the western world.

More recent data (2016) indicate that severe acute malnutrition including kwashiorkor and marasmus affects more than 18 million children each year, most living in low-income settings. [2]  According to 2018 WHO data, 52 million children younger than 5 years are wasted (low weight-for-height), 17 million are severely wasted, and 155 million are stunted (low height-for-age). [23]

A 2018 systematic review and meta-analysis of 1989-2017 data regarding the prevalence of underweight and wasting in Iranian children younger than 5 years found regional differences, which the investigators believed could be attributed to the varying level of development in these areas. [24] The prevalence of underweight among children at the national level was 6%, with the lowest at 5% in western Iran and the highest in central Iran. The prevalence of pediatric wasting was 4% at the national level, with the lowest at 4% in western Iran and the highest in southen Iran. [24]

A cross-sectional study of Palestinian adolescents found inadequate energy intake in 55.66% of boys and 64.81% of girls, and inadequate protein intake in 15.07% of boys and 43.08% of girls. [25]  The recommended daily allowance for micronutrients was met by less than 80% of the study subjects.

Dermatologic findings appear more significant and occur more frequently among darker-skinned peoples. This finding is likely explained by the greater prevalence and the increased severity of protein-energy malnutrition in developing countries and not to a difference in racial susceptibility.

Marasmus most commonly occurs in children younger than 5 years. This period is characterized by increased energy requirements and increased susceptibility to viral and bacterial infections. Weaning (the deprivation of breast milk and the commencement of nourishment with other food) occurs during this high-risk period. Weaning is often complicated by geography, economy, hygiene, public health, culture, and dietetics. It can be ineffective when the foods introduced provide inadequate nutrients, when the food and water are contaminated, when the access to health care is inadequate, and/or when the patient cannot access or purchase proper nourishment.

In some studies, the protein-energy malnutrition prevalence among elderly persons is estimated to be as high as 4% for those living in the community, 50% for those hospitalized in acute care units or geriatric rehabilitation units, and 30-40% for those in long-term care facilities. A 2019 systematic review, meta-analysis, and meta-regression of the prevalence of protein-energy malnutrition among the elderly found that rural communities were affected twice as much as urban communities and women were affected more than males. [26] Other recent studies of geriatric patients hospitalized for orthopedic conditions [27] or heart failure [28] also note protein-energy malnutrition is prevalent in this population.



The extent of growth failure and the severity of hypoproteinemia, hypoalbuminemia, and electrolyte imbalances are predictors of a poorer prognosis. Additionally, underlying human immunodeficiency virus (HIV) infection is associated with a poor prognosis. 

Approximately 45% deaths each year in developing countries occur because of malnutrition in children younger than 5 years. [2, 13, 23] In kwashiorkor, mortality tends to decrease as the age of onset increases.

Protein-energy malnutrition has also been found to be a primary factor of poor prognosis in elderly persons. In a study designed to assess the quality of care in nursing home residents, there was a direct association between mortality and anorexia in elderly residents of both genders with an almost two-fold higher risk of death for all causes in patients with anorexia. [29] In a separate propensity-matched study of 32,771 elderly patients hospitalized for heart failure, protein-match malnutrition was associated with higher mortality, cardiogenic shock, cardiac arrest, acute kidney failure, acute respiratory failure, and mechanical ventilation. [28]

Patients with liver cirrhosis are also at risk for protein-energy malnutrition, [30] which portends a poor prognosis for survival. [31] Protein-energy malnutrition is associated with an increased risk of liver cirrhosis complications, including ascites, variceal bleeding, hepatic encephalopathy, and hepatorenal syndrome. [30, 32]


Complications of protein-energy malnutrition can be many, including the following [33] :

  • Hypothermia
  • Hypoglycemia
  • Encephalopathy
  • Diarrhea
  • Heart failure
  • Infection

Another important complication of malnutrition is micronutrient defiencies. Vitamin deficiencies can be seen, with deficiencies in the fat-soluble vitamins (A, D, E, and K) being more common. Vitamin A deficiency can have ocular effects, causing night blindness among other problems; vitamin D deficiency can have bony effects; vitamin E deficiency can cause neuropathy and ataxia; and vitamin K deficiency can cause bleeding.

Deficiencies in the water-soluble vitamins has a multitude of effects. Folic acid (vitamin B9) and cobalamin (vitamin B12) deficiency can both cause megaloblastic anemia. Deficiency in thiamine (vitamin B1) can cause beriberi and high-output heart failure, whereas deficiency riboflavin (vitamin B2) can cause glossitis and seborrheic dermatitis. Niacin (vitamin B3) deficiency can result in pellagra, leading to dermatitis, dementia, diarrhea, and weakness. Pyridoxine (vitamin B6) deficiency can lead to neuropathy, irritability, and weight loss. 

Minerals or trace elements such as phosphorus, iron, and zinc can also be deficient in protein-energy malnutrition. Phosphate deficiency, if severe, can cause rhabdomyolysis, bone pain, or osteomalacia. Iron deficiency can lead to microcytic anemia and, if severe, can result in cardiomegaly, lethargy, and impaired psychomotor and mental development. Zinc deficiency can lead to growth failure, increased infections, and cognitive dysfunction.


Patient Education

Education regarding adequate nutrition starts with the mother, often prior to childbirth. It is important to educate the mother to be healthy during pregnancy to meet the nutritional demands not only of her child, but also herself. Educating these women regarding the importance of breastfeeding and how to adequately nourish a child is also essential.