Enteropathy

Etiological and functional classification

According to their origin, enteropathies are divided into two large groups. Infectious enteropathy is the most common in clinical practice. Its development is triggered by pathogens such as Shigella, Salmonella, Yersinia, as well as various viruses and parasites.

Non-infectious lesions occur less frequently and are associated with:

• Alimentary causes (systematic unbalanced nutrition).
• Toxic effects (chronic alcohol abuse, smoking).

Depending on morphological changes in the small intestine wall, the disease may occur with or without enterocyte dystrophy, be accompanied by partial villous atrophy, and localize predominantly in the ileum (ileitis).

From a functional standpoint, the pathology is characterized by:

1. Impairment of membrane digestion (a characteristic example is disaccharidase deficiency).
2. Disorders of absorption processes (malabsorption of water, electrolytes, vitamins, proteins, fats, carbohydrates, and iron).
3. Impairment of intestinal motility (hyperkinetic or hypokinetic type of motility disorders develops).

Pathogenesis

The initial link of pathogenesis is always the impairment of the barrier function of the previously damaged intestinal wall. Following this, the main pathogenetic mechanisms unfold:

• There is a sharp decrease in the activity of both free enzymes and those bound to the enterocyte membrane. This inevitably leads to a severe disorder of membrane digestion.
• The proper functioning of transport channels is disrupted. As a result, the absorption of ions, water, and final products of nutrient hydrolysis is blocked.

The disease often takes a chronic course due to the formation of vicious circles. This is facilitated by so-called aggravating factors: a decrease in the enzymatic activity of all digestive glands in the body, pronounced dysbiosis, systemic metabolic disorders, and a drop in the effectiveness of immune defense.

Intestinal manifestations

Local symptoms directly depend on the localization of the inflammatory or dystrophic process.

• If the initial section of the jejunum is affected, the pathology is latent, with minimal intestinal manifestations.
• If the process involves the ileum, bile acid absorption suffers critically. Accumulating in the intestinal lumen, bile acids actively stimulate the secretion of water, sodium, and chloride ions, and sharply activate motility. The result of this mechanism is profuse diarrhea.
• With a prolonged course of reflux ileitis, vitamin $B_{12}$ absorption is impaired, which naturally leads to the development of $B_{12}$-deficient anemia.

Typical intestinal symptoms in enteropathies also include flatulence and steatorrhea (presence of excess fat in the stool).

Extraintestinal manifestations (malabsorption syndrome)

Systemic signs of the disease are caused by the development of malabsorption syndrome—a total impairment of nutrient absorption. The condition is accompanied by profound metabolic shifts.

Patients exhibit a marked weight loss, often exceeding 20 kg. Trophic changes develop: the skin becomes dry, thinned, and flaky, hair loss begins intensively, and nail plates thicken and become brittle. Due to protein deficiency, hypoproteinemia occurs, leading to peripheral edema.

Impaired electrolyte absorption impacts the cardiovascular and nervous systems:

• Hypokalemia provokes cardiac arrhythmias and a tendency toward hypotensive reactions.
• Hypocalcemia causes paresthesias and specific spasms of small muscles. Striking markers are Chvostek sign (local contraction of facial muscles upon light tapping just below the zygomatic arch) and Trousseau sign (wrist flexion into an "obstetrician's hand" position when a pressure cuff is applied to the arm).

The clinical picture is complemented by diverse symptoms of total vitamin deficiency.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanisms of steatorrhea development in impaired enzymatic function
• The role of dysbiosis in the formation of vicious circles in enteritis
• Types of disaccharidase deficiency and membrane digestion disorders
• Differences in the pathogenesis of enteropathies from irritable bowel syndrome (IBS) and ulcerative colitis (UC)

Other topics in "Chapter 24. Typical Forms of Digestive System Pathology"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.