Protein energy malnutrition overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Omodamola Aje B.Sc, M.D. [2]
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 in either marasmus or kwashiokor. 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 oedema. 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 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 came from the Ga language of Accra, Ghana meaning the disease of 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 Water low classification based on stunting and wasting or the Welcome classification based on the presence or absence of edema.
Pathophysiology
Different pathophysiologic mechanisms are involved in the development of protein energy malnutrition as it comprises of two main diseases, kwashiorkor and marasmus. 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 understand. Several theories have been put forward to explain this finding. Marasmus on the other hand is due to the total caloric deficiency leading to wasting in 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 very little 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 edema, wasting, failure to thrive, recurrent infections, skin and hair changes. It is important to also differentiate kwashiorkor from marasmus as the two diseases belong to the protein energy malnutrition.
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 diseases of the developing countries. There is no racial or sexual predisposition.
Risk Factors
Screening
Natural History, Complications and Progonosis
Diagnosis
History and Symptoms
Symptoms of kwashiorkor
Symptoms of kwashiorkor include a swollen abdomen known as a pot belly, as well as reddish discoloration of the hair and depigmented skin. The swollen abdomen is generally attributed to two causes: First, the observation of ascites due to increased capillary permeability from the increased production of cysteinyl leukotrienes (LTC4 and LTE4) as a result of generalized intracellular deficiency of glutathione. It is also thought to be attributed to the effect of malnutrition on reducing plasma proteins (discussed below), resulting in a reduced oncotic pressure and therefore increased osmotic flux through the capillary wall. A second cause may be due to a grossly enlarged liver due to fatty liver. This fatty change occurs because of the lack of apolipoproteins which transport lipids from the liver to tissues throughout the body. Victims of kwashiorkor fail to produce antibodies following vaccination against diseases including diphtheria and typhoid.[3] Generally, the disease can be treated by adding food energy and protein to the diet; however, mortality can be as high as 60% and it can have a long-term impact on a child's physical growth and, in severe cases, affect mental development.