Secretory diarrhea

Introduction Secretory diarrhea refers to diarrhea caused by excessive secretion of water and electrolytes from the gastrointestinal tract. The mechanism of secretory diarrhea involves a variety of factors, among which cAMP plays an important role. cAMP in intestinal mucosal cells induces secretion of electrolytes and water, and cAMP requires intracellular adenylate cyclization. Enzyme catalysis can work. Enterotoxin (an exotoxin) secreted by Vibrio cholerae can rapidly bind to jejunal epithelial cells, stimulate adenylate cyclase, increase intracellular cAMP content, and accelerate the process of water and electrolyte secretion into the intestinal lumen. When the intestinal secretion exceeds its absorption capacity, diarrhea occurs.

Cause

Secretory diarrhea is caused by the salt and water secreted by the small intestine and colon beyond its absorption capacity. Substances that stimulate the secretion of the intestine include bacterial toxins (such as cholera), viruses that cause bowel disease, bile acids (such as after ileal resection), unabsorbed food fats (such as steatorrhea), and certain drugs (such as diarrhea). Agents, castor oil, prostaglandins) and peptide hormones (such as intestinal vasoactive peptides from pancreatic tumors). Microscopic colitis (collagen or lymphocytic colitis) accounts for 5% of secretory diarrhea.

Intestinal secretion is mainly the function of mucosal crypt cells, and absorption depends on the role of epithelial cells in the intestinal villus. The mechanism of secretory diarrhea involves a variety of factors, among which cAMP plays an important role. cAMP in intestinal mucosal cells induces secretion of electrolytes and water, and cAMP requires intracellular adenylate cyclization. Enzyme catalysis can work. Enterotoxin (an exotoxin) secreted by Vibrio cholerae can rapidly bind to jejunal epithelial cells, stimulate adenylate cyclase, increase intracellular cAMP content, and accelerate the process of water and electrolyte secretion into the intestinal lumen. When the intestinal secretion exceeds its absorption capacity, diarrhea occurs.

an examination

Related inspection

Rectal examination of urinary citrulline and feces

The clinical features of secretory diarrhea are:

(1) Discharge a large amount of watery stools, which can reach several liters per day.

(2) The feces contain a large amount of electrolyte, and its osmotic pressure is substantially the same as the plasma osmotic pressure.

(3) There is no pus in the feces.

(4) Diarrhea does not stop after fasting.

(5) Generally no abdominal pain.

(6) The histological examination of the intestinal mucosa is basically normal.

Laboratory inspection:

1. Fecal examination: the most basic examination for diarrhea, including appearance, microscopic examination and culture. Microscopic examination of red blood cells, white blood cells, eggs, protozoa and so on. Different staining of smears can achieve different testing purposes. For example, Gram staining can be used for bacteriological examination, pay attention to the proportion of clubs, Sudan III staining can check for fat droplets, and iodine staining can check for starch granules. Fungal profiling of feces contributes to the etiological diagnosis of diarrhea.

2, blood routine.

Differential diagnosis

Viral diarrhea: As the name implies, it is caused by a virus. In particular, rotavirus (named after the appearance of the virus particles like a wheel) is more common, and most of them occur in autumn and winter (also in other seasons), also known as autumn diarrhea. Main features: first vomiting and diarrhea, accompanied by fever, stool is watery or egg-flower soup, the course of disease is self-limiting, that is, the use of drugs can not significantly change the course of the disease.

Habitual diarrhea: In the autumn, the gas turns cold, and the number of patients with diarrhea increases. According to the statistics of the intestine clinics of major hospitals, diarrhea patients accounted for the majority due to improper diet and cold, and those with repeated diarrhea and chronic diarrhea increased the most. According to the doctor, these patients are "stretched", have abdominal pain, are in a hurry, and frequently have loose stools. However, the laboratory tests for no virus, but it is cured for a long time and is habitual diarrhea.

Physiological diarrhea: more common in infants under 6 months, the appearance of puffiness, often eczema, diarrhea soon after birth, daily stools, or even more than a dozen times, each time the amount of stool is not necessarily a lot, which contains a small amount of water, Generally no special odor is found. In addition to the increased frequency of bowel movements, infants with physiological diarrhea have no other symptoms, good appetite, no vomiting, and growth and development are not affected. After adding complementary food, the stool gradually turns to normal.

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