Markers of malnutrition
Last reviewed: 23.04.2024
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Disturbance of nutrition - a condition caused by a change in food intake or a violation of its utilization by the body, which leads to disruption of functions at the subcellular, cellular and organ levels. The malnutrition syndrome can develop with a deficit in the body of any of the essential nutrients (proteins, energy sources, vitamins, macro- and microelements). However, in clinical practice, protein or protein-energy malnutrition is most often observed. As a rule, with pronounced protein-energy deficiency, signs of deficiency of certain vitamins, macro- and microelements are noted. Insufficiency of nutrition with violation of the trophic status in all its varieties (protein, energy, vitamin, etc.) is observed in 20-50% of patients with surgical and therapeutic profile.
Nutrition assessment is now an obligatory component of medical care for hospitalized patients in leading clinics of the most developed countries of the world. The Joint Commission for the Accreditation of Health Organizations (JCAHO) requires compliance of nutritional requirements for patients with certain standards, which include:
- assessment of the patient's nutritional status;
- registration of clinical manifestations of eating disorders;
- Monitoring changes in the status of nutrition and the patient's response to the adjustments made.
The process of nutrition evaluation includes various methods that can be conditionally divided into 4 groups:
- methods for assessing food;
- anthropometric (somatometric);
- clinical;
- laboratory.
These methods can be used to assess nutrition separately, but the most appropriate combination of them.
Anthropometric methods for estimating nutrition are the most accessible and include measurement:
- height (body length);
- body weight;
- circumference of the abdomen, neck, shoulder, etc .;
- thickness of skin-fat folds at standard points;
- Calculation of body mass index [ratio of body weight (kg) to height (m), squared].
Anthropometric methods have great advantages: they are simple, harmless, non-invasive, can be carried out at the patient's bed, do not require expensive equipment. However, they have their shortcomings, which include:
- low sensitivity (do not allow to detect short-term violations of trophic status and do not identify specific deficiencies);
- the inability to distinguish between disturbances caused by a deficiency of any nutrient, from disturbances caused by an imbalance between protein and energy intake;
- Some conditions of the patient (edema, obesity, loss of skin elasticity, turgor disturbance) do not allow accurate measurements.
Clinical methods for assessing nutrition include anamnesis and physical examination to detect signs and symptoms associated with trophic status disorder. In most cases, these signs can be detected only in the progressing stage of exhaustion. Therefore, clinical assessments do not allow the detection of eating disorders in the early clinical or preclinical stages.
Recently, in clinical practice, more and more preference is given to laboratory methods of nutritional assessment. With primary and secondary nutritional deficiencies, tissue depots are gradually depleted, resulting in a decrease in the level of these substances or their metabolites in certain environments of the body, which can be detected by laboratory methods. The use of laboratory methods is also preferable from the economic side, since it allows to detect initial signs of a deficit before the development of the clinical syndrome (hence, fewer funds will be spent for treatment), and also to detect a deficiency of specific nutrients.
All laboratory tests for nutritional assessment can be divided into 2 categories:
- determination of the concentration of substances in the serum of the patient;
- determination of the rate of excretion of substances with urine.
In the serum of blood there are newly absorbed substances, received from food. Therefore, the concentration of the substance in the blood serum reflects the present (in time) intake of the substance with food, that is, assesses the status of nutrition at a time, rather than for a long period, which is very important in the treatment of emergency conditions. If the kidney function in the patient is not disturbed, the urine test allows you to assess the metabolism of minerals, vitamins and proteins. Excretion of these substances with urine also reflects a one-moment nutritional status, rather than status over a long period of time.
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