Marasmus

Marasmus is a state of extreme emaciation; the name is derived from the Greek |iapao|ioo for wasting. It is the predictable outcome of prolonged negative energy balance with severe depletion of all energy reserves in the body.

Table 8.2 Classification of protein-energy malnutrition in children

No oedema Oedema

60-80% of expected weight for age Underweight Kwashiorkor

< 60% of expected weight for age Marasmus Marasmic kwashiorkor

Not only have the body's fat reserves been exhausted, but there is wastage of muscle as well, and as the condition progresses there is loss of protein from the heart, liver and kidneys, although as far as possible essential tissue proteins are protected. As discussed in section 9.2.3.3, protein synthesis is energy expensive, and in marasmus there is a considerable reduction in the rate of protein synthesis, although catabolism continues at the normal rate (section 9.1.1). The amino acids released by the catalysis of tissue proteins are used as a source of metabolic fuel and as substrates for gluconeogenesis to maintain a supply of glucose for the brain and red blood cells (section 5.7).

As a result of the reduced synthesis of proteins, there is a considerable impairment of the immune response, so that undernourished people are more at risk from infections that those who are adequately nourished. Diseases that are minor childhood illnesses in developed countries can often prove fatal to undernourished children in developing countries. Measles is commonly cited as the cause of death among children in developing countries, although it would invariably be more correct to give the true cause of death as malnutrition — infection is simply the last straw.

One of the proteins secreted by the liver that is most severely affected by protein-energy malnutrition is the plasma retinol-binding protein, which transports vitamin A from liver stores to tissues where it is required (section 11.2.2.2). As the synthesis of retinol-binding protein is reduced, so there are increasing signs of vitamin A deficiency, although there may be adequate reserves of the vitamin in the liver. Without the binding protein, liver reserves cannot be transported to the tissues where they are required. It is quite common for signs of vitamin A deficiency to be associated with protein-energy malnutrition, but supplements of vitamin A have no effect, as the problem is in the transport and utilization of the vitamin. Nevertheless, as discussed in section 11.2.4, dietary deficiency of vitamin A is also a serious problem in many developing countries and further impairs immune responses.

A more serious effect of protein-energy malnutrition is impairment of cell proliferation in the intestinal mucosa (section 4.1). The villi are shorter than usual, and in severe cases the intestinal mucosa is almost flat. This results in a considerable reduction in the surface area of the intestinal mucosa, and hence a reduction in the absorption of such nutrients as are available from the diet. As a result, diarrhoea is a common feature of protein-energy malnutrition. Thus, not only does the undernourished person have an inadequate intake of food, but the absorption of what is available is impaired, so making the problem worse.

8.3.1 Causes of marasmus and vulnerable groups of the population

In developing countries, the causes of marasmus are either a chronic shortage of food or the more acute problem of famine, where there will be very little food available at all. All too frequently, famine comes on top of a long-term shortage of food, so its effects are all the more rapid and serious.

A lack of food is unlikely to be a problem in developed countries, although the most socially and economically disadvantaged in the community are at risk of hunger and perhaps even protein—energy undernutrition in extreme cases. Two factors may cause marasmus in developed countries: disorders of appetite and impairment of the absorption of nutrients.

8.3.1.1 Disorders of appetite: anorexia nervosa and bulimia

As discussed in section 6.2.1, there is considerable pressure on people in Western countries to be slim. We are bombarded with more or less well- or ill-informed articles about obesity in magazines and newspapers and on radio and TV; many of the fashion models and media stars who provide role models for young people are extremely thin.

While obesity is indeed a serious health problem (see section 6.2.2), one effect of the propaganda is to put considerable pressure on people to reduce their body weight, even if they are within the acceptable and healthy weight range. In some cases this pressure may be a factor in the development of anorexia nervosa — a major psychological disturbance of appetite and eating behaviour. The group most at risk are adolescent girls, although similar disturbances of eating behaviour can occur in older women and (more rarely) in adolescent boys and men.

The main feature of anorexia nervosa is a refusal to eat — with the obvious result of very considerable weight loss. Despite all evidence and arguments to the contrary, the anorectic subject is convinced that she is overweight and restricts her eating very severely. Dieting becomes the primary focus of her life. She has a preoccupation with, and often a considerable knowledge of, food, and frequently has a variety of stylized compulsive behaviour patterns associated with food. As a part of her pathological obsession with thinness, the anorectic subject frequently takes a great deal of strenuous exercise, often exercising to exhaustion in solitude. She will go to extreme lengths to avoid eating, and frequently when forced to eat will induce vomiting soon afterwards. Many anorectics also make excessive use of laxatives.

Surprisingly, many anorectic people are adept at hiding their condition, and it is not unknown for the problem to remain unnoticed, even in a family setting. Food is played with, but little or none is actually eaten; excuses are frequently made to leave the table in the middle of the meal, perhaps on the pretext of going into the kitchen to prepare the next course.

Some anorectic subjects also exhibit a further disturbance of eating behaviour — bulimia or binge eating. After a period of eating little or nothing, they suddenly eat an extremely large amount of food (40 MJ or more in a single meal, compared with an average daily requirement of 8—12 MJ), frequently followed by deliberate induction of vomiting and heavy doses of laxatives. This is followed by a further prolonged period of anorexia.

Bulimia also occurs in the absence of anorexia nervosa — a person of normal weight will consume a very large amount of food (commonly 40—80 MJ over a period of a few hours), again followed by induction of vomiting and excessive use of laxatives. In severe cases such binges may occur five or six times a week.

Anorexia nervosa and bulimia are psychological problems, and require sensitive specialist treatment. It is not simply a matter of persuading the patient to eat. One theory is that the root cause of the problem, at least in adolescent girls, is a reaction to the physical changes of puberty. By refusing food, the girl believes that she can delay or prevent these changes. To a considerable extent this is so. Breast development slows down or ceases as the energy balance becomes more negative and, as body weight falls below about 45 kg, menstruation ceases.

It is estimated that about 2% of adolescent girls go through at least a short phase of anorexia. In most cases it is self-limiting and normal eating patterns are re-established as the emotional crises of adolescence resolve. Other people may require specialist counselling and treatment, and in an unfortunate few problems of eating behaviour persist into adult life.

8.3.1.2 Malabsorption

Any clinical condition that impairs the absorption of nutrients from the intestinal tract will lead to undernutrition, although the intake is apparently adequate. The problem is one of digestion and/or absorption of the food.

Obviously, major intestinal surgery will result in a reduction in the amount of intestine available for the digestion and absorption of nutrients. In this case, the problem is known in advance, and precautionary measures can be taken: a period of intravenous feeding, to supplement normal food intake, and careful counselling by a dietitian, so as to ensure adequate nutrient intake despite the problems.

A variety of infectious diseases can cause malabsorption and diarrhoea. In many cases, this lasts only a few days and so has no long-term consequences. However, a number of intestinal parasites can cause long-lasting diarrhoea and damage to the intestinal mucosa, leading to malnutrition if the infection remains untreated for too long.

8.3.1.3 Food intolerance and allergy

It was noted in section 4.4.3.2 that relatively large peptides derived from dietary proteins can be absorbed intact, and these can stimulate the production of antibodies — this is the basis of food allergy. Allergic reactions to foods may include dermatitis, eczema and urticaria, asthma, allergic rhinitis, muscle pain, rheumatoid arthritis and migraine, as well as effects on the gastrointestinal tract. All of these are likely to impair the sufferer's appetite, and hence may contribute to undernutrition. There can be serious damage to the intestinal mucosa, leading to severe malabsorption, and hence malnutrition despite an apparently adequate intake of food. One of the best understood such conditions is coeliac disease.

Coeliac disease is an allergy to one specific protein in wheat — the gliadin fraction of wheat gluten. The result is a considerable loss of intestinal mucosa and flattening of the intestinal villi, so that the appearance of the intestine is similar to that seen in marasmus. This reduction in the absorptive surface of the intestine leads to persistent fatty diarrhoea (steattorhoea) and a failure to absorb nutrients. The result is undernutrition; although the intake of food is apparently adequate, there is inadequate digestion and absorption of nutrients. Severe emaciation can occur in patients with untreated coeliac disease.

Once the diagnosis is established, and the immediate problems of undernutrition have been dealt with, treatment is relatively simple — avoidance of all wheat and rye-based products. In practice, this is less easy than it sounds - apart from the obvious foods, such as bread and pasta, wheat flour is used in a great many food products. There is therefore a need for counselling from a dietitian, and careful reading of labels for lists of ingredients. A number of products have the symbol of the Coeliac Society on the label, to show that they are known to be free from gluten and therefore safe for patients to eat.

A number of other intolerances or allergic reactions to foods can also lead to similar persistent diarrhoea, loss of intestinal mucosa and hence malnutrition. The problem of disaccharide intolerance was discussed in section 4.2.2.2. In general, once the offending food has been identified, the patient's condition has stabilized and body weight has been restored, continuing treatment is relatively easy, although avoidance of some common foods may provide significant problems.

It is the identification of the offending food that poses the greatest problem and frequently calls for lengthy investigations, maintaining the patient on a very limited range of foods then gradually introducing additional foods until the offending item is identified.

Patients with food intolerances or allergies are generally extremely ill after they have eaten the offending food, and this may persist for several days. Even after the offending foods have been identified, and the patient's condition has been stabilized, there may be continuing problems of appetite and eating behaviour.

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