Marasmus

Background

Marasmus is one of the 3 forms of serious protein-energy malnutrition (PEM). The other 2 forms are kwashiorkor (KW) and marasmic KW. These forms of serious PEM represent a group of pathologic conditions associated with a nutritional and energy deficit occurring mainly in young children from developing countries at the time of weaning. Marasmus is a condition primarily caused by a deficiency in calories and energy, whereas kwashiorkor indicates an associated protein deficiency, resulting in an edematous appearance. Marasmic kwashiorkor indicates that, in practice, separating these entities conclusively is difficult; this term indicates a condition that has features of both.

These conditions are frequently associated with infections, mainly GI. The reasons for a progression of nutritional deficit into marasmus rather than kwashiorkor are unclear and cannot be solely explained by the composition of the deficient diet (ie, a diet deficient in energy for marasmus and a diet deficient in protein for kwashiorkor). The study of these phenomena is considerably limited by the lack of an appropriate animal model. Unfortunately, many authors combine these entities into one, thus precluding a better understanding of the differences between these clinical conditions.

Marasmus is a serious worldwide problem that involves more than 50 million children younger than 5 years. According to the World Health Organization (WHO), 49% of the 10.4 million deaths occurring in children younger than 5 years in developing countries are associated with PEM.

Pathophysiology

Various extensive reviews of the pathophysiological processes resulting in marasmus are available. Unlike kwashiorkor, the clinical sequelae of marasmus can be considered as an evolving adaptation in a child facing an insufficient energy intake. Marasmus always results from a negative energy balance. The imbalance can result from a decreased energy intake, an increased loss of ingested calories (eg, emesis, diarrhea, burns), an increased energy expenditure, or combinations of these factors, such as is observed in acute or chronic diseases. Children adapt to an energy deficiency with a decrease in physical activity, lethargy, a decrease in basal energy metabolism, slowing of growth, and, finally, weight loss.

Pathophysiological changes associated with nutritional and energy deficits can be described as (1) body composition changes, (2) metabolic changes, and (3) anatomic changes.

Anatomic Changes

The entire digestive tract from mouth to rectum is affected. The mucosal surface becomes smooth and thin, and secretory functions are impaired. A decrease in gastric hydrochloric acid (HCl) excretion and a slowing of peristalsis is observed, yielding bacterial overgrowth in the duodenum. Proportionally, the digestive tract is the organ system that loses the largest mass during marasmus. However, these important alterations of the digestive tract interfere only moderately with normal nutrient absorption. Therefore, early enteral renutrition is not contraindicated but is encouraged because some of the nutrients necessary for the recovery of the intestinal mucosa are used directly from the lumen.

In addition to the anatomic changes associated with PEM, the frequent intestinal infections by viruses and bacteria and the toxins they produce also contribute to the changes in the digestive tract. Liver volume usually decreases, as do other organ volumes. An enlarged liver suggests the possibility of other diagnoses, such as kwashiorkor or hepatitis. Liver synthetic function is usually preserved, although protein synthesis is decreased, as reflected by the decreased albumin and prealbumin levels. Glycogen synthesis is decreased, further increasing the risk for hypoglycemia. The detoxifying function of the liver is impaired with structural changes in the liver cells. Therefore, drugs that are metabolized by the liver should be administered with caution, and liver function should be monitored.

Body Composition

• Body mass: Body mass is significantly decreased in a heterogeneous way.
• Fat mass: Fat stores can decrease to as low as 5% of the total body weight and can be macroscopically undetectable. The remaining fat is usually stored in the liver, giving a paradoxical appearance of a fatty liver. Although this is often observed in kwashiorkor, it also occurs to a lesser extent in marasmus. A study from Nigeria examined serum lipids in malnourished children.^[6] These authors found that total cholesterol, low density lipoprotein cholesterol, and high density lipoprotein cholesterol levels were significantly higher in children with kwashiorkor than in those with marasmus.
• Total body water: The proportion of water content in the body increases with the increased seriousness of PEM (marasmus or kwashiorkor) and is associated with the loss of fat mass, which is poor in water. The proportion of extracellular water also increases, often resulting in edema. Edema is significant in kwashiorkor but can also be present in marasmus or in the frequently encountered mixed forms of PEM. The increase in extracellular water is proportional to the increase in the total body water. During the first days of therapy, part of the extracellular water shifts to the intracellular compartment and part of it is lost in the urine, resulting in the observed initial weight loss with treatment.
• Protein mass: Mainly represented by muscle and some organs (eg, heart), protein mass can decrease as much as 30% in the most serious forms. The muscle fibers are thin with loss of striation. Muscle cells are atrophic, and muscle tissue is infiltrated with fat and fibrous tissue. Total recovery is long but appears to be possible.
• Other organ mass: The brain, skeleton, and kidney are preserved, whereas the liver, heart, pancreas, and digestive tract are first affected.
• Pediatric and adult physiologic change: Finally, physiologic changes are different in infants and children when compared with adults. For example, infants with marasmus have an increased tendency to hypothermia and hypoglycemia, requiring the frequent administration of small meals. This can be explained by the body composition imbalance of children with marasmus in favor of high-energy–consuming organs, such as the brain and kidney, compared with energy-storage organs, such as muscle and fat.
• Assessment of fat and muscle mass: As described below, assessment of the fat and muscle mass loss can be clinically performed by measuring arm circumference (see image below) or skinfold thickness, such as triceps skinfold. The diagram illustrates the validity of this assessment method. Because arm circumference is relatively constant in healthy children aged 1-5 years, it roughly represents a general assessment of nutritional status.