Malnutrition is defined by the Council on Food and Nutrition of the American Medical Association as a state of functional, structural, and developmental alteration of the organism resulting from a discrepancy between specific nutritional requirements and the intake and use of nutrients. According to a broader definition proposed by Stratton in 2003, malnutrition is when a deficit or excess of energy, protein, and other nutrients causes effects on body composition and/or on the functionality of organs and/or tissues.

Malnutrition can be due to:

 • Increased food requirements

 • Inadequate use of food

 In malnutrition, the balance between intake and demand for a nutrient can be skewed either too high (overnutrition) or too low (undernutrition). However, in general terms, malnutrition refers to a lack of nutrients. High-risk conditions for malnutrition are:

 • Childhood and adolescence (high demand for energy and essential nutrients)

• Pregnancy and lactation (increased need for all nutrients)

• Advanced age (decreased physical activity, psycho-social problems, etc.)

• Chronic diseases

• Vegetarian diets (iron deficiency)

• Fad diets (deficiency of vitamins, minerals, and proteins)

 • Alcohol or drug addiction (altered lifestyle, high absorption and metabolism of nutrients, etc.)

 Undernutrition may be due to inadequate intake, malabsorption, systemic loss of nutrients due to diarrhea, excessive sweating, hemorrhage, severe burns, kidney failure, infection, and drug use. Risk factors for undernutrition are:

 • Severe underweight: body mass index (BMI) 10% of usual body weight during a 3-month period

• Alcohol intake >170 ml per day

 • No oral intake for >10 days

 • Prolonged loss of nutrients due to malabsorption syndromes, short bowel syndromes, fistulas, diabetes, renal dialysis, secreting abscesses, or wounds

 • Increased metabolic demand due to extensive burns, infection, trauma, prolonged fever, or hyperthyroidism

 • Intake of drugs with antinutritive or catabolic properties (e.g., appetite depressants, corticosteroids, immunosuppressants, and anticancer drugs)

 Overnutrition, on the other hand, may be due to overeating, poor exercise, parenteral nutrition, vitamin overdose (vitamin B6, niacin, A, and D), or mineral trace element overdose. The main risk factors are as follows:

 • Good appetite combined with a lack of exercise and weight gain

 • High-fat, high-salt diet

• High doses of nicotinic acid for hypercholesterolemia

 • High doses of pyridoxine for premenstrual syndrome

• High doses of vitamin A for skin disorders

• High doses of iron and other mineral trace elements without a prescription

 From a clinical point of view, the most important problems are associated with protein-energy malnutrition (PEM), an energy deficit due to a deficiency of all macronutrients, which can manifest itself in an acute or chronic form.

Malnutrition initially causes the breakdown of adipose tissue for energy, followed by protein depletion or imbalance. Since proteins are involved in many physiological processes, PEM directly compromises the organs’ function and negatively impacts several systems and apparatuses, including the immune system. Visceral organs and muscles are also destroyed, resulting in weight loss. Organ weight loss is greatest in the liver and intestines, intermediate in the heart and kidneys, and minimal in the nervous system. The increasing number of individuals of advanced age and patients pre disposed to malnutrition determines the existence of a population with marked chronic PEM.

PEM can be primary, caused by inadequate nutrient intake, or secondary to diseases or medications that interfere with nutrient utilization. Primary PEM generally affects children and the elderly lacking access to nutrients, although depression is a frequent cause in the elderly. Primary PEM can also result from fasting or anorexia nervosa.

Secondary PEM, on the other hand, may be due to the:

 • Changes in gastrointestinal function, such as impaired digestion (pancreatic insufficiency), impaired absorption (enteropathies, inflammatory bowel disease), or impaired lymphatic transport of nutrients (retroperitoneal fibrosis)

 • Pathological conditions that cause wasting, such as neo plasms or hemodialysis

 • Pathological conditions that increase metabolic requirements, such as infections, hyperthyroidism, pheochromocytoma, other endocrine disorders, burns, trauma, surgery, and other critical illnesses

Malnutrition is a rather frequent condition in cancer patients, with a prevalence between 25% and 70% in various European and non-European countries. Cancer patients show alterations in nutritional status even in the extremely early stages of the disease, such as immediately after radical surgery and, therefore, in the absence of metastases. The consequences of malnutrition in these patients include an increased risk of infections, fatigue, and reduced muscle function; about 20–30% of cancer patients die from the direct and indirect consequences of malnutrition. The risk of malnutrition and its severity depends on the type of cancer, its stage, and the therapy employed. In addition, malnutrition has a negative impact on prognosis, response and tolerance to therapy, and quality of life. Indeed, malnutrition is a truly independent predictor of increased morbidity and mortality, and loss of body weight and muscle mass induces an increased risk of chemotherapy toxicity.

Malnutrition is also a common problem in patients with chronic kidney disease, especially those undergoing hemodialysis treatment. It has been estimated that about 40% of hemodialysis patients present with varying degrees of mal nutrition, and about 10% present with severe malnutrition. Many factors are related to malnutrition in dialysis patients, including the dialysis procedures themselves. The uremic state is the most important factor. It is associated with inflammation and endocrine-metabolic alterations that induce catabolic processes by inhibiting anabolic ones and reducing appetite. The survival of adequately dialyzed patients depends mainly on their age and nutritional status.

Obesity is the most common form of overnutrition. According to the World Health Organization (WHO), obesity is one of the main public health problems in the world, representing a truly global epidemic, with a prevalence that is on the rise and growing at a worrying rate, not only in Western countries but also in low-income countries. In addition, obesity is a major risk factor for various chronic diseases, such as type 2 diabetes mellitus, cardiovascular disease, and cancer. It is estimated that 44% of cases of type 2 diabetes, 23% of cases of ischemic heart disease, and up to 41% of some cancers are attributable to obesity. Overall, obesity is the fifth most important risk factor for global mortality, and deaths attributable to obesity are at least 2.8 million per year worldwide. WHO has estimated that the prevalence of obesity globally has doubled from 1980 to 2018, affecting the youngest segments of the population. It is estimated that there were over 40 million overweight children under 5 years of age worldwide in 2011. Table 1 summarizes the main causes of primary and secondary obesity.

Table1. Cause of obesity

According to the WHO, obesity is defined as a BMI ≥30 kg/m2.

BMI is calculated according to the following formula:

 BMI = weight (kg)/ height² (m). =

Based on BMI, various categories are distinguished (Table 2).

Table2. Body weight classification based on BMI

Assessment of nutritional status is important to:

 • Identify patients with nutritional problems (already mal nourished or at risk of caloric-energetic malnutrition or with depletion of specific nutrients) who require specific therapeutic intervention

• Frame and manage a patient

 • Monitor the adequacy of any nutritional support

There is no gold standard for the assessment of nutritional status. It is currently based on the integration of anamnestic data (physiological, pathological, and in-depth nutritional history), clinical evaluations (accurate and objective examination), anthropometric measurements (body weight, BMI, plicometry, cross-sectional area of the arm), and biochemical parameters.

The nutritional status should be assessed in the following cases:

 • High-risk patients

 • Subjects with recent significant weight loss; a significant weight loss is defined as an unintentional weight loss in the last 6 months >10% compared to the usual weight or greater than 5% in 1 month. In the absence of usual weight, body weight 20% below ideal weight may be considered indicative of malnutrition

 • Subjects with loss of appetite for 2–3 weeks

• Subjects on enteral or parenteral nutrition

مواضيع ذات صلة

HIV drug resistance testing (HIV genotype)

herpes simplex (Herpesvirus types 1 and 2, Herpes simplex virus types 1 and 2 [HSV 1, HSV 2], Herpes genitalis)

hepatitis virus studies

Biomarkers of Nutritional Status

hemoglobin (Hb, Hgb)

hematocrit (Hct, Packed red blood cell volume, Packed cell volume [PCV])

Helicobacter pylori testing (Anti–Helicobacter pylori antibody, Campylobacter-like organism [CLO] test, H. pylori stool antigen)

Nonculture Methods For The Identification Of Pathogenic Microorganisms

Heinz body preparation

Haptoglobin

Transthyretin (Prealbumin)

 C-reactive protein