Etiology

The causes of PEM in infants are the following:

Prenatal factors:

• Diseases of pregnant women (kidney, cardiovascular pathology, ARVІ, diabetes mellitus).

• Toxicosis of І and ІІ part of pregnancy

• Regimen and quality of feeding of pregnant women

• Stresses

• Ecological pollution of environment

• Treatment with medicines, use of alcohol, smoking during pregnancy

• Diseases of placenta

Postnatal factors:

1. Alimentary factors: quantitative undernutririon (hypogalactia, administration of insufficient quantity of mixtures) or qualitative undernutrition (insufficiency of proteins, vitamins, trace elements).

2. Infectious factors: intrauterine generalized infections, sepsis, pyelonephritis and urinary tract infections, other foci ofinfection, which lead to hypovitaminoses, disorders of utilizationof nutritional substances in intestine and tissues. Infectious diseases of gastrointestinal tract leading to prolonged diarrhea, morphologic changes of intestine mucous membrane, including atrophy of intestinal villi are the most often cause of hypotrophy.

3. Zinc and other trace elements deficiency, hypovitaminoses, toxic factors (ecological, hypervitaminosis A or D, drugs poisoning etc.).

4. Anorexia because of perinatal or other brain diseases, unfavorable factors of surroundings, neuroses.

5. Malformations of mouth, gastrointestinal tract such asileus, pylorostenosis etc.

6. Syndrome of "short bowel" after extensive intestinal resections.

7. Syndromes of malabsorption (intolerance of lactose, saccharose, glucose, protein of cow or soya milk; celiac disease, cystic fibrosis of pancreas, exudative enteropathy, enteropathicacrodermatitis, atrophy of villi of small intestine.

8. Hereditary anomalies of metabolism (galactosemia, leucinosis, fructosemia, diseases of Niman-Pick, Tey-Saks), immunodeficiencies (predominantly of T-system).

Pathogenesis

Despite of different causes leading to malnutrition, there is disorder of utilization of nutritional substances (proteins first of all) both in intestine and in tissues. All patients proportionally to deficiency of body weight to height have elevated excretion of nitrous substances with urine and disorder of ratio between nitrogen of urea and total nitrogen of urine. This ratio is named "index of protein nutrition" (IPN). IPN in healthy children, not depending on type of feeding, makes up 83-85%; in malnourished infants it usually decreases (70-35%); in excessive protein feeding it is always elevated.

Activity of gastric, intestine, pancreatic enzymes is decreased, as a rule, proportionally to degree of body weight deficit; because of it nutritional load adequate to healthy infant may cause acute disorder of digestion (dyspepsia) in sick one. Intestine in such children is elongated, dilated, so constipations are typical, as well as dysbacteriosis.

Functions of liver (protein-synthetic, antitoxic, carbohydrative, acetylizing, etc.), heart, kidneys, and lungs are disturbed. Anemia isn’t rare, not only because of protein deficiency, but because of deficiency of zinc, copper, iron, folic acid, piridoxin.

Here there are not disorders of humoral immunity, but disorders of phagocytes activity of neutrophiles and macroph-ages, depression of T-system with lymphocytopenia (deficit of T-helpers is obvious, so as activity of T-suppressors is normal or slightly decreased) are typical, that leads to frequent infectious processes, which may have latent course.

Hypoproteinemia, hypoalbuminemia, aminoaciduria, plane sugar curves and susceptibility to hypoglycemia, acidosis, hy-pokalemia, hypokalehystia, hypernatrhystia, retention of sodium, hypocalcemia, hypophosphatemia are typical. Disorders of sodium and potassium metabolism are connected probably with activation of renal glands. In mild degrees of hypotrophia there are signs of activation of sympatho-adrenal system that is considered as chronic stress; on the contrary, in severe hypotrophy functional insufficiency of internal glands activity may occur. Hypovolemia is typical for all patients. They are susceptible to cooling.