Protein deficiency is a common worldwide problem, which involves a number of serious complications. Proteins belong among essential nutrients and they represent important building material for body tissues. Proteins enable enzyme functions and participate in immune response. Therefore, the lack of proteins leads the disruption of the whole organism.
Worldwide, the most common cause of protein deficiency is the low dietary intake. This is especially the case of so-called developing African countries. In developed civilized countries, protein deficiency is usually related to another illness such as chronic alcoholism, anorexia nervosa and malabsorption syndrome. Low protein level is often observed in patients with liver diseases (e.g. liver cirrhosis) because liver is the main producer of the proteins used in the organism. We must not forget diseases that cause excessive protein loss into the urine (see relevant text). Too high protein loss into urine is referred to as the nephrotic syndrome. Significant protein loss is also present when there is disrupted skin cover in extensive burns and diseases associated with severe skin damage (e.g. Lyell's syndrome). Very rare disease associated with protein loss is the Ménétrier’s disease, which is accompanied by abnormally large mucosal folds in the stomach.
In hospitalized patients, the most threatened by protein deficiency are patients in critical condition in intensive care units. They suffer from reduced food intake and protein catabolism in strenuous situation.
Protein deficiency typically manifests with swelling. Protein molecules in blood help to keep the blood fluid within the vessels. In protein deficiency, blood fluid escapes the blood vessels into neighboring tissue causing their edema. The patients usually suffer from swelling of the lower extremities, but the first sign may be swelling of eyelids. The total muscle mass decreases, the immune system is weakened, wound healing is delayed and patient's nails break easily. When the protein deficiency is present from childhood, we talk about the so-called kwashiorkor. Children with the kwashiorkor suffer from severe from serious tissue swelling including ascites, fatty liver, loss of teeth, brittle hair, chronic skin inflammation and impaired mental development.
Protein levels can be evaluated from a sample of venous blood. We are interested not only in total protein level but also in concentration of albumin and prealbumin. It is important to rule out excessive protein losses, especially by gastrointestinal tract or in urine.
If possible, it is important to ensure protein-rich diet to increase the protein intake. Patients in severe conditions, who are unable to eat enough food by mouth must be fed parenterally (by special infusions with nutrients). Enteral nutrition by nasogastric tube or by PEG is also possible and it has many advantages against the parenteral nutrition. If protein deficiency is caused by malabsorption, or by excessive protein losses, it is necessary to treat the underlying condition as well.