Between the extremes of starvation and adequate nutrition, there are various degrees of inadequate nutrition, such as protein-energy malnutrition, the leading cause of death in children of developing countries.
Protein-energy malnutrition is caused by an inadequate consumption of calories, resulting in a deficiency of proteins and micronutrients (nutrients required in small quantities, such as vitamins and trace minerals). Rapid growth, an infection, an injury, or a chronic debilitating disease can increase the need for nutrients, particularly in infants and young children who are already malnourished.
There are three types of protein-energy malnutrition: dry (a person is thin and dehydrated), wet (a person is puffy because of fluid retention), and an intermediate type between the two extremes.
The dry type, called marasmus, results from almost total starvation. A child who has marasmus consumes very little food often because the mother is unable to breastfeed, and is very thin from the loss of both muscle and body fat.
Almost invariably, an infection develops. If the child is injured or if the infection becomes widespread, the prognosis is worse and the child’s life is jeopardized.
The wet type is called kwashiorkor, an African word meaning “first child-second child.” It comes from the observation that the first child develops kwashiorkor when the second child is born and replaces the first child at the mother’s breast. The weaned first child is fed a thin gruel that’s low in nutritional quality compared with mother’s milk, so the child does not thrive. The protein deficiency in kwashiorkor is usually more significant than the calorie (energy) deficiency, resulting in fluid retention (edema), skin disease, and discoloration of the hair. Because children develop kwashiorkor after they are weaned, they are usually older than those who have marasmus.
The intermediate type of protein-energy malnutrition is called marasmic kwashiorkor. Children with this type retain some fluid and have more body fat than those who have marasmus.
Kwashiorkor is less common than marasmus and usually occurs as marasmic kwashiorkor. It tends to be confined to parts of the world (rural Africa, the Caribbean, the Pacific islands, and Southeast Asia) where staples and foods used to wean babies-such as yams, cassava, rice, sweet potatoes, and green bananas-are protein-deficient and excessively starchy.
In marasmus, as in starvation, the body breaks down its own tissues to use as calories. Carbohydrates stored in the liver are depleted, proteins in muscle are broken down to synthesize new proteins, and stored fat is broken down to produce calories. As a result, the entire body shrinks.
In kwashiorkor, the body is less able to synthesize new proteins. Consequently, blood levels of proteins decrease, causing fluids to accumulate in the arms and legs as edema. Cholesterol levels also decrease and an enlarged fatty liver (excessive of accumulation of fat inside the liver cells) develops. The protein deficiency impairs body growth, immunity, the ability to repair damaged tissues, and the production of enzymes and hormones. In marasmus and kwashiorkor, diarrhea is common.
Behavioral development may be markedly slow in the severely malnourished child, and mental retardation may occur. Usually, an infant who has marasmus is affected more severely than an older child who has kwashiorkor.
An infant who has protein-energy malnutrition is usually given intravenous feedings during the first 24 to 48 hours after hospitalization. Because such infants invariably have serious infections, an antibiotic is usually included in the intravenous fluids. A milk-based formula is given by mouth as soon as it can be tolerated. The amount of calories given is gradually increased, so that an infant who weighed 13 to 17 pounds when admitted to the hospital gains about 7 pounds over 12 weeks.
Up to 40 percent of the children who have protein-energy malnutrition die. Death during the first days of treatment is usually caused by an electrolyte imbalance, an infection, an abnormally low body temperature (hypothermia), or heart failure. Stupor (semi consciousness), jaundice, tiny skin hemorrhages, a low sodium level in the blood, and persistent diarrhea are ominous signs. The disappearance of apathy, edema, and lack of appetite is a favorable sign. Recovery is more rapid from kwashiorkor than from marasmus.
The long-term effects of malnutrition in childhood are unknown. When children are adequately treated, the liver and immune system recover completely. However, in some children, the absorption of nutrients in the intestine remains impaired. The degree of mental impairment is related to how long a child was malnourished, how severe the malnutrition was, and at what age it began. A mild degree of mental retardation may persist into school age and possibly beyond.