Protein energy malnutrition overview

# Overview
Protein energy malnutrition is defined by measurements that fall below 2 standard deviations under the normal weight for age (underweight), height for age (stunting) and weight for height (wasting). Protein energy malnutrition is a nutritional deficiency resulting from either inadequate energy (caloric) or protein intake and manifesting as either marasmus or kwashiorkor. Marasmus is characterized by wasting of body tissues, particularly muscles and subcutaneous fat, and is usually a result of severe restrictions in energy intake. Kwashiorkor affects mainly children, is characterized by edema (particularly ascites), and is usually the result of severe restrictions in protein intake. However, both types can be present simultaneously (marasmic-kwashiokor) and mask malnutrition due to the presence of edema. Treatment involves prompt resuscitation, identification of co-morbidities like dehydration and infections. The presence of severe of hypoproteinemia, hypoalbuminemia, electrolyte imbalance or an underlying HIV infection is associated with poorer prognosis among patients with protein energy malnutrition.

# Historical Perspective
The first clinical description of protein-energy malnutrition was made in 1865 in Spanish language which led to little dissemination of the information. In 1932, kwashiorkor was first described by Dr. Cicely Williams, working with African children on the Gold Coast. The word kwashiorkor comes from the Ga language of Accra, Ghana meaning the 'diseaseof the deposed baby when the next one is born'. The term marasmus is derived from the Greek word 'marasmos', which means withering or wasting.

# Classification
Protein energy malnutrition may be classified according to the 'Gomez classification' based on weight for age, or the 'Waterlow classification' based on stunting and wasting, or the 'Welcome classification' based on the presence or absence of edema.

# Pathophysiology
Protein-energy malnutrition represents a shift of the body from fed to fasting/starvation state. Starvation leads to a decreased basal plasma insulin concentration and in decrease of glucose-stimulated insulin secretion. Prolonged fasting results in a deficiency in amino acids used for gluconeogenesis. It is thought that kwashiorkor is produced by a deficiency in the adequate consumption of protein-rich foods during the weaning process. However, the associated edema is not fully understood. Several theories have been put forward to explain this finding. Marasmus on the other hand is thought to be due to the total caloric deficiency leading to wastingin a child. Marasmus always results from a negative energy balance.

# Causes
Protein energy malnutrition may be caused by reduced breast feeding, poor weaning practices, limited availability of food and inadequate child care in cases of extreme poverty. This classically affects several poor people in regions of poor social and economic background. Other environmental causes such as infections, drought and earthquakes leading to decreased availability of food have also been identified.

# Differentiating Kwashiorkor from other Diseases
Protein-energy malnutrition must be differentiated from other diseases that cause failure to thrive, edema, wasting recurrent infections, skin and hair changes. It is important to also differentiate kwashiorkor from marasmus as the two diseases are casued by protein- energy malnutrition and share similar features such as, weight loss, muscle wasting, low blood glucose levels and growth retardation.

# Epidemiology and Demographics
The prevalence of protein-energy malnutrition in children under 5 is estimated to be 150 million cases annually. In Nigeria, the prevalence is as high as 41,600 per 100,000 children. Protein-energy malnutrition is majorly a disease of the developing countries. There is no racial or sexual predisposition.

# Risk Factors
Common risk factors in the development of protein-energy malnutrition may be classified as maternal and environmental.

# Screening
There is insufficient evidence to recommend routine screening for protein-energy malnutrition.

# Natural History, Complications and Prognosis
If left untreated, all children with protein energy malnutrition will progress to develop permanent stunting (height for age), poorly developed immune system which causes overwhelming bacteremia and sepsis which is the cause of death in most malnourished individuals.

# Diagnosis

## History and Symptoms
The history of protein-energy malnutrition includes a failure to thrive in children under 1 year of age especially after they have just been weaned of breast milk. Some common signs and symptoms include failure to thrive, fatigue, irritability, changes in skin and hair pigment, decreased muscle mass, diarrhea, increased occurrence of severe infectionsdue to damaged immune system, edema and hepatomegaly.

## Physical Examination
Physical examination of patients with kwashiorkor is usually remarkable for rounded prominence of the cheeks known as the moon face, and distended abdomen due to an enlarged liver, hyperkeratosis and hyperpigmentation of the skin, generalized edema especially on the dependent areas of the body like the feet. On the other hand, patients with marasmus usually look listless, emaciated with monkey-like faces due to absence of subcutaneous fat pad in the cheeks. The skin looks atrophic and dry.

## Laboratory Findings
There are no specific laboratory tests, group of tests, or indices that are satisfactory for the assessment of protein-energy malnutrition. However, laboratory findings that may aid in the diagnosis of protein-energy malnutrition include abnormally low blood glucose, hypoalbuminemia (10-25 g/L), hypoproteinemia (transferrin, essential amino acids, lipoprotein) and hypoglycemia.

## X ray
There are no chest X ray findings associated with protein energy malnutrition.

## CT
There are no CT scan findings associated with protein energy malnutrition.

## MRI
There are no MRI findings associated with protein energy malnutrition. However, a MRI may be helpful in the diagnosis of complications of protein-energy malnutrition which include cerebral atrophy and ventricular dilation.

## Echocardiography or Ultrasound
Echocardiography findings may be helpful in the diagnosis of protein-energy malnutrition. Findings on an echocardiography suggestive of protein-energy malnutrition include decrease of R wave and QTc interval, decreased cardiac index which improved significantly after rehabilitation.

## Other Imaging Findings
There are no other imaging findings associated with protein-energy malnutrition.

## Other Diagnostic Studies
There are several parameters that can be used in the assessment of a child with protein-energy malnutrition. Malnutrition can be assessed according to the WHO based on mid upper arm circumference into moderate and severe malnutrition. Other parameters include the Z-score which assesses linear growth and weight for length.

# Treatment

## Medical Therapy
In some cases, protein-energy malnutrition may be complicated by dehydration and specific infections, such as pneumonia and septicemia. In such cases, protein-energy malnutrition is a is a medical emergency and requires prompt treatment with antibiotics.

## Surgery
Surgical intervention is not recommended for the management of protein-energy malnutrition.

## Primary Prevention
To prevent kwashiorkor, make sure the diet has enough carbohydrates, fat (at least 10% of total calories), and protein (12% of total calories).

## Secondary Prevention
The secondary prevention of protein-energy malnutrition is the same as primary prevention.