بسمه تعالى

NUTRITIONAL DISEASES

Dr. Teeb M. Jaafar

M.B.Ch.B./ F.I.C.M.S (path)

Malnutrition

Malnutrition, also referred to as protein energy malnutrition or (PEM), is a consequence of inadequate intake of protein and calories, or deficiencies in the digestion and absorption of proteins resulting in loss of fat and muscle tissues, weight loss, lethargy and generalized weakness.

Millions of people in developing nations are malnourished and starving, or living on the cruel edge of starvation.

In the industrial world and, more recently, also in developing countries,obesity has become a major public health problem, associated with the development of diseases such as diabetes and atherosclerosis.

•Dietary Insufficiency:•An appropriate diet should provide:

Sufficient energy, in the form of carbohydrates, fat and protein for the body's daily metabolic needs.

Amino acids and fatty acids to be used as building blocks for synthesis of structural and functional proteins and lipids.

Vitamins and minerals, which function as coenzymes in vital metabolic pathways or, as in case of calcium and phosphate, as important structural components.

In primary malnutrition, one or all of these components

are missing from the diet.

By contrast in secondary malnutrition, the supply of

nutrient is adequate but malnutrition results from insufficient

intake, malabsorption, impaired utilization or storage, excess loss

or increased need for nutrients.

There are several conditions that may lead to dietary insufficiency:

Poverty: homeless persons, aged individuals and children of poor

families often suffer from PEM as well as trace nutrient deficiencies.

Infection: PEM increases the susceptibility to many common

infectious diseases and vice versa.

Acute and chronic illnesses: the basal metabolic rate becomes

accelerated in many illnesses resulting in increased daily

requirements for all nutrients. Failure to recognize these nutritional

needs may delay recovery. PEM is often presents in patients with

wasting diseases such as advanced cancers and AIDS.

Chronic alcoholism: alcoholic persons may sometimes suffer PEM, but morefrequently have deficiency of several vitamins, especially thiamine, pyridoxine,folate and vitamin A.

Ignorance and failure of diet supplement: even the affluent may fail to recognizethat infants, adolescents and pregnant women have increased nutritional needs.Ignorance about the nutritional contents of various food is also a contributingfactor.

Self- imposed dietary restriction: anorexia nervosa, bulimia and less overt eatingdisorders affect many individuals who are concerned about body image and areobsessed with body weight.

Other causes: additional causes of malnutrition includes (gastrointestinal diseasesand malabsorption syndromes, genetic diseases, specific drug therapies whichblock uptake or utilization of particular nutrients and total parenteral nutrition.

Protein- Energy Malnutrition (PEM):

Severe PEM is a serious, often lethal disease affecting children. It is acommon in low-income countries, where up to 25% of children may beaffected, and where it is a major factor in the high death rates amongchildren younger than 5 years.

Malnutrition is determined according to the body mass index (BMI):

BMI=weight in kilograms/ height in meters squared.

A BMI less than 16kg/m2 is considered malnutrition (normal range is 18.5 to 25 kg/m2). In more practical way, a child whose weight falls to less than 80% of normal (provided in standard tables) is considered malnourished.

Marasmus and Kwashiorkor

in malnourished children, PEM presents as a range of clinical syndromes, all characterized by a dietary intake of protein and calories inadequate to meet the body's needs. The two ends of spectrum of PEM syndromes are known as marasmus and kwashiorkor.

From a functional standpoint, there are two differentially regulated protein compartments in the body: the somatic compartment, represented by protein in skeletal muscles and the visceral compartment, represented by protein stores in the visceral organs, primarily the liver.

Child is considered to have marasmus when weight falls to 60% of

normal of sex, height and age. A marasmic child suffers growth

retardation and loss of muscle, the latter resulting from catabolism and

depletion of the somatic protein department. This seems to be an

adaptive response that provides the body with amino acids as a source

of energy. The visceral protein compartment, which is presumably more

precious and critical for survival, is only marginally depleted, and hence

serum albumin level are either normal or slightly reduced. In addition to

muscle protein, subcutaneous fat is also mobilized and used as fuel.

With such loses of muscle and subcutaneous fat, the extremities are

emaciated; by comparison, the head appears too large for the body.

Kwashiorkor occurs when protein deprivation is relatively greater than the reduction in total calories. This is the most common form of PEM seen in African children who have been weaned too early and subsequently fed, almost exclusively, a carbohydrate diet.

In kwashiorkor, marked protein deprivation is associated with severe loss of visceral protein compartment, and the resultant hypoalbuminemia gives rise to generalized or dependent edema.

•The loss of weight in these patients is masked by the increased fluid retention. In further contrast to marasmus, there is relative sparing of subcutaneous fat and muscle mass. Children with kwashiorkor have characteristic skin lesion, with alternating zones of hyperpigmentation, areas of desquamation, and hypopigmentation giving a "flaky paint" appearance. Hair changes include overall loss of color or alternating bands of pale and darker hair.

Other features that differentiate kwashiorkor from marasmus includes:

• an enlarged fatty liver,

• vitamin deficiencies are likely to be present,

• defect in immunity and secondary infections.

As already stated, marasmus and kwashiorkor are two ends of a

spectrum, and considerable overlap exists between these conditions.

Cachexia:PEM is a common complication in patient with AIDS or advanced cancers, and in these settings it is known as cachexia.

Cachexia occurs in about 50% of cancer patients, most commonly in patients with gastrointestinal, pancreatic and lung cancers, and is responsible for about 30% of cancer deaths. It is a highly debilitating condition characterized by extreme weight loss, fatigue, muscle atrophy, anemia, anorexia and edema. Mortality is generally the consequence of atrophy of the diaphragm and other respiratory muscles. The precise cause of cachexia are not known, but it is clear that agents secreted by tumors and host responses contributes to its development.

Anorexia Nervosa and Bulimia:

Anorexia nervosa is self-induced starvation, resulting

in marked weight loss. Bulimia is a condition in which

the patient binges on food and then induces vomiting.

Anorexia nervosa has the highest death rate of any

psychiatric disorder. Bulimia is more common than

anorexia, and generally has a better prognosis.

The clinical findings in anorexia nervosa are

generally similar to those in severe PEM. In addition,

effects on the endocrine system are prominent.

Amenorrhea, resulting from decreased secretion of

gonadotropin-releasing hormone and subsequent

decreased secretion of luteinizing hormone and follicle-

stimulating hormone, is so common that its appearance

is a diagnostic feature for the disorder.

In bulimia, binge eating is the norm. Large amount of food, principally carbohydrates, are ingested, only to be followed by induced vomiting.

The major medical complication relate to continual induced vomiting, and the chronic use of laxatives and diuretics includes:

Electrolyte imbalances (hypokalemia), which predispose the patient to cardiac arrhythmias.

Pulmonary aspiration of gastric contents.

Esophageal and gastric cardiac rupture.

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