Congenital disorders of the structure of the intestinal mucosa

Conducting differential diagnostics for osmotic diarrhea requires excluding digestion and absorption disorders, congenital diseases with disruption of enterocyte structure, and immune-inflammatory diseases.

The so-called chronic intractable diarrhea in newborns begins in the first days or weeks of life, does not have a provoking infectious factor, and is characterized by a severe life-threatening course. Unlike digestion and absorption disorders, diarrhea does not stop when enteral nutrition is discontinued. Such conditions may be associated with congenital disorders of the enterocyte structure.

Congenital microvillous atrophy (microvillous switch-off syndrome) is characterized by the presence of cytoplasmic inclusions containing microvilli in the area of the apical pole of the enterocyte; there are no microvilli on the analogous surface of the mature enterocyte. These disorders can be detected by electron microscopy. The pathology is probably associated with a defect in endo- or exocytosis and a disruption of the membrane restructuring process. Recent studies have revealed disruptions in glycoprotein exocytosis. Light microscopy of mucosal biopsies reveals villous atrophy and accumulation of PAS-positive material at the apical pole of enterocytes.

ICD-10 code

P78.3. Noninfectious diarrhea in newborn.

Symptoms

The typical clinical picture is characterized by the onset of watery diarrhea in the first days of the child's life, sometimes with mucus in the stool. Diarrhea is so intense that it leads to dehydration within a few hours; the child can lose up to 30% of body weight per day. The stool volume is 150-300 ml/kg of body weight per day, the sodium content in the stool is increased (100 mmol/l). Metabolic acidosis develops. Transfer to total parenteral nutrition allows to reduce the stool volume somewhat, but not less than 150 ml/kg per day. Combination with malformations of other organs is uncharacteristic. Some children develop itchy skin due to an increase in the concentration of bile acids in the blood. In some cases, signs of dysfunction of the proximal renal tubules are noted.

An important differential diagnostic sign, in addition to the persistence of diarrhea during total parenteral nutrition, is considered to be the absence of polyhydramnios in the mother with this disease, in contrast to chloride and sodium diarrhea.

Treatment

Children are shown lifelong parenteral nutrition. Rapid development of cholestasis and liver dysfunction is typical. Secondary infection and septic condition often occur. Patients with microvillous atrophy often need intestinal transplantation.

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