What is Protein-energy Deficiency?
With insufficient intake of protein and energy, lean body mass and the amount of adipose tissue are reduced, and one of these changes may be more pronounced.
Protein deficiency is a pathological condition that develops as a result of a reduction or cessation of protein intake in the body. It may also be due to increased protein breakdown in the body, for example, in case of a burn disease, severe trauma, purulent-septic disease.
In developing countries, protein-energy deficiency is common; during periods of hunger, its prevalence can reach 25%.
Primary protein-energy deficiency occurs in cases where socio-economic factors do not allow for ensuring an adequate amount and quality of food – in particular, if mainly vegetable proteins with low biological value are used for food. Plays a role and the high prevalence of infections.
Protein deficiency is exacerbated with insufficient energy, because in this case the amino acids of food are not used for protein synthesis, but are oxidized for energy.
In developing countries, children have 2 forms of protein-energy deficiency – marasmus and kwashiorkor.
Marasmus is characterized by growth retardation, muscle atrophy (due to protein utilization) and subcutaneous tissue; no swelling. The disease is caused by insufficient intake of both protein and energy.
With kwashiorkor (isolated protein deficiency) growth retardation, edema, hypoalbuminemia, and fatty degeneration of the liver are observed. Subcutaneous tissue preserved.
Both adults and children can have mixed forms; differences between protein-energy and isolated protein deficiency are not of great clinical significance.
In developed countries, secondary protein-energy deficiency, which develops on the background of acute or chronic diseases, is most often observed. The reasons are a decrease in appetite, increased basal metabolism, malabsorption, alcoholism and drug addiction; in the elderly – depression, loneliness, poverty. Half of the hospitalized elderly are already exhausted at the time of admission to the hospital or developing during the period of hospitalization.
Primary and secondary protein-energy deficiency can be combined. Thus, with insufficient nutrition, an increase in the basal metabolic rate and a decrease in appetite, characteristic of infections, lead to the appearance of clinical signs of exhaustion more quickly than in a normal nutritional status.
Isolated protein-energy deficiency is rare. Usually it is accompanied by a deficiency of other food components – folic acid, vitamin B1, vitamin B2 and vitamin B6, nicotinic acid, vitamin A. Aviation deficiency is especially dangerous in children with protein-energy deficiency. phosphorus and magnesium, and this loss is proportional to the excretion of nitrogen. Therefore, against the background of the restoration of nutritional status, symptoms of deficiency of these substances may appear.
Pathogenesis during Protein-energy Deficiency
Adaptation of the body to energy deficiency, in which the intake of calories does not provide the minimum energy requirement, includes hormonal changes. These changes contribute to the mobilization of free fatty acids from adipose tissue and amino acids from muscles. Gluconeogenesis and oxidation of amino acids provide the formation of energy needed for other organs, especially the brain. As a result, protein synthesis is reduced, metabolism slows down, lean body mass decreases and the amount of adipose tissue decreases. In the first week of fasting, weight loss is 4-5 kg (25% is accounted for by fatty tissue, 35% by extracellular fluid, 40% by proteins). In the future, weight loss slows down. The various components of the body are utilized at different speeds: skeletal muscle – faster than the heart muscle, gastrointestinal organs and liver – faster than the kidneys. Skeletal muscle proteins are used to synthesize albumin, so hypoalbuminemia develops later.
By eating mainly vegetable proteins with low biological value, as well as in cases where only glucose solution is used for parenteral nutrition, protein deficiency may develop. This increases the secretion of insulin, which inhibits lipolysis and the mobilization of proteins of skeletal muscles. The level of amino acids in the blood decreases, the synthesis of albumin and other proteins decreases. As a result, hypoalbuminemia, edema, and fatty degeneration of the liver, characteristic of kwashiorkor, develop.
Mineral deficiencies are partly due to weight loss and loss of extracellular fluid. Losses of potassium and magnesium can be disproportionately high due to the mobilization of intracellular stocks of these substances. The deficit is exacerbated by insufficient intake of minerals (for example, parenteral nutrition using only glucose as an energy source) and an increase in their losses (increased diuresis, diarrhea, fistula).
Fasting usually does not lead to rapid death. Adaptation of the body to energy deficiency includes the satisfaction of the energy needs of the central nervous system due to the oxidation of fatty acids and ketone bodies, slowing down the metabolism, contributing to the preservation of protein reserves. More dangerous fasting for acute or chronic diseases. They contribute to an increase in basal metabolism, accelerate weight loss, as well as the loss of nitrogen and essential components of food. Whether this effect is due to the direct metabolic effects of inflammation, infection, fever, and wound healing or mediated by the action of inflammatory mediators such as AF alpha, IL-2 and IL-6 is not entirely clear.
Thus, severe protein-energy deficiency develops with inadequate nutrition against the background of acute or chronic diseases. So, it is often observed with AIDS e (probably due to decreased appetite, fever and diarrhea).
Symptoms of Protein-energy Deficiency
Light and moderate protein-energy deficiency. Children do not gain weight and height. In adults, there is a decrease in weight, although with edema or obesity it may not be as noticeable. The thickness of the skin fold above the triceps muscle of the shoulder and the muscle mass in the shoulder area are reduced.
In the absence of kidney disease, the ratio of daily creatinine excretion to growth (measured weekly) is a sensitive indicator of protein deficiency. The levels of albumin, transferrin and transthyretin (prealbumin) in the blood are reduced. The level of T3 decreases, while the reverse T3 increases. Metabolism slows down. Possible lymphopenia and impaired glucose tolerance. The size of the heart is reduced.
Severe protein-energy failure. Severe protein-energy deficiency is accompanied by more pronounced changes in clinical and laboratory parameters. Physical examination reveals a retraction of the intercostal spaces, atrophy of the temporal muscles and atrophy of the muscles of the extremities. Subcutaneous tissue is atrophied or absent. Typical apathy, fatigue, feeling cold, depigmentation of the skin and depigmentation of hair, sharpened facial features; skin is dry, cracked. In advanced cases, bedsores are formed, the skin ulcerates. Blood pressure is reduced, as well as body temperature, the pulse is weakened. The functions of all organs and systems are impaired.
Cardiovascular system, respiratory system and kidneys. Fan reaction to hypoxia weakened. The mass of the heart and kidneys decreases in accordance with a decrease in lean body mass and a slower metabolism, and therefore cardiac output and GFR, although decreasing, still correspond to the needs of the body. However, heart failure is possible with infection, stress, as well as with the rapid restoration of BCC and nutritional status.
Blood. BCC, hematocrit, albumin and transferrin levels, as well as the number of lymphocytes in the blood are reduced. Normocytic normochromic anemia develops, usually due to a decrease in erythropoiesis due to a decrease in protein synthesis. Anemia is exacerbated by a deficiency of iron, folic acid and vitamin B6.
Metabolism. The basal metabolic rate and body temperature are lowered, apparently due to a drop in the T3 level and a loss of the heat insulating function of the subcutaneous tissue. In the terminal stage hypoglycemia develops.
Gastrointestinal tract and pancreas. Atrophy of intestinal villi, enhanced microflora growth in the small intestine; exocrine and endocrine functions of the pancreas are violated. There are impaired absorption and lactose intolerance. These symptoms may be due not to starvation itself, but to atrophy of the gastrointestinal tract from inaction, since similar changes are noted with full parenteral nutrition.
The immune system. Humoral immunity is usually preserved; laboratory tests reveal a violation of cellular immunity. Often develop pneumonia and other infections, including opportunistic.
Healing wounds. Wound healing (including operating) is slow. The edges of the wound often diverge.
Reproductive system. Egg implantation, growth and development of the fetus are impaired. Childbirth proceeds with complications, lactation decreases. A newborn is stunted; in surviving children, cognitive impairment is further possible.
Treatment of Protein-energy Deficiency
With mild and moderate protein-energy deficiency should eliminate the possible causes of this condition. The daily intake of proteins and energy increase (in accordance with the ideal weight) to eliminate their deficiency. All patients prescribed multivitamins. They also treat and prevent the deficiency of mineral substances (including trace elements) to prevent life-threatening hypokalemia, hypomagnesemia, hypophosphatemia, etc. If the patient is able to eat and swallow, self-sufficient power is enough. With a decrease in appetite or in the absence of teeth, an additional liquid nutrient mixture is prescribed for independent or probe nutrition.
With severe protein-energy deficiency, more urgent intervention is required. The treatment of such patients is difficult for several reasons:
- The diseases that caused protein-energy deficiency are difficult, they are more difficult to treat. Sometimes the nitrogenous balance can be restored only after the infection is cured and the fever is eliminated.
- Protein-energy deficiency itself can impede the cure of the serious illness that caused it. In such cases, it is necessary to begin as early as possible probe or parenteral nutrition.
- Food intake through the gastrointestinal tract contributes to diarrhea due to atrophy of the mucous membranes and deficiency of enzymes of the intestine and pancreas. In this case, complete parenteral nutrition may be indicated.
- The accompanying deficiency of other food components (vitamins, essential minerals, trace elements) should be eliminated.
In adults, the restoration of nutritional status occurs slowly and not always completely; in children recovery occurs within 3-4 months. In all cases, educational and rehabilitation programs are needed, as well as psychological and social support measures.