bubble_chart Overview

Protein-losing gastroenteropathy syndrome (PLG syndrome), also known as protein-losing gastroenteropathy or sometimes referred to as protein fistula disease or exudative gastroenteropathy, is a syndrome caused by various factors that lead to the loss of plasma proteins, particularly albumin, from the gastrointestinal mucosa. Clinically, it primarily manifests as systemic edema and hypoproteinemia.

bubble_chart Etiology

The exact mechanism of protein loss from the gastrointestinal tract is unclear, but current theories favor a multifactorial etiology, associating it with various diseases:

1. Diseases involving abnormalities of the gastrointestinal mucosal epithelium: Such as hypertrophic gastritis, stomach cancer, ulcerative colitis, regional enteritis, Crohn's disease, intestinal cancer, or any other inflammatory or ulcerative lesions. These conditions can lead to the leakage of plasma proteins from the damaged mucosa into the intestinal lumen. If this exceeds the liver's compensatory capacity, hypoproteinemia may result.

2. Diseases involving abnormalities of the gastrointestinal or systemic lymphatic vessels: These include thoracic duct lymphatic obstruction, constrictive pericarditis, congestive heart failure, impaired intestinal lymphatic drainage, and small intestine lymphangiectasia. In constrictive pericarditis and congestive heart failure, hypoproteinemia primarily arises from increased central venous pressure, which impedes lymphatic return via the thoracic duct, leading to intestinal protein loss. Small intestine lymphangiectasia may be a congenital defect where rupture of dilated lymphatic vessels causes the loss of plasma proteins and lymphocytes from the intestines.

3. Diseases characterized by increased capillary permeability: Examples include intestinal tumors with telangiectasia, allergic gastroenteropathy, and gastrointestinal mucosal metabolic disorders. These conditions exhibit heightened capillary permeability, resulting in protein loss. A classic example is adult celiac disease.

bubble_chart Pathological Changes

Hypoproteinemia can result from four pathophysiological changes: ① acquired reduction in protein synthesis; ② congenital reduction in protein synthesis; ③ increased protein catabolism; ④ excessive loss of protein in urine and feces.

bubble_chart Clinical Manifestations

Due to the loss of plasma proteins, especially albumin, the colloid osmotic pressure decreases, leading to secondary hyperaldosteronism, which causes sodium and water retention. As a result, patients may experience generalized edema, particularly noticeable in the lower limbs. Additionally, symptoms such as pleural effusion, ascites, weight loss, and anemia may occur, with children potentially suffering from developmental delays. Gastrointestinal symptoms can include loss of appetite, nausea, vomiting, diarrhea, and abdominal pain. Calcium loss may induce hand and foot convulsions. Small intestine lymphangiectasia often involves immunoglobulin loss and abnormal cellular immunity, with weakened lymphocyte blastogenesis in response to phytohemagglutinin, making patients more susceptible to pulmonary infections.

bubble_chart Auxiliary Examination

(1)¹³¹I-PVP: PVP (polyvinylpyrrolidone) is a macromolecular substance that is rarely absorbed in the digestive tract. After intravenous injection of 10–15 microcuries, feces free of urine are collected for 4 days for measurement: normal individuals excrete only 0%–1.5%, while patients with this disease may excrete up to 2.9%–32.5%. In recent years, some have used ⁵⁹

F_e-dextran as a substitute for ¹³¹I-PVP.

(2)⁵¹Cr_r-albumin and ⁵¹Cr_r-transferrin: After intravenous injection of 25 microcuries of ⁵¹Cr_ralbumin, feces free of urine are collected for 4 days. Normal individuals excrete 0.1%–0.7%, while patients with this disease excrete 2%–40%. Recently, some have reported that intravenous injection of 10 microcuries of 51Crr-transferrin is even more effective. Since labeled albumin or transferrin is almost not absorbed from the gastrointestinal tract and is not secreted from normal digestive fluids (such as saliva or gastric juice), it is highly valuable for understanding the loss of gastrointestinal proteins. Because ⁵¹Cr_r can be excreted in urine, it is essential to ensure that fecal specimens are not mixed with urine during collection.

Additionally, X-ray gastrointestinal barium meal examinations, lymphangiography, endoscopy, and other tests can be performed to aid in diagnosis.

bubble_chart Diagnosis

Based on clinical manifestations, especially generalized edema accompanied by hypoproteinemia, this disease should be considered, and a diagnosis can be made with further laboratory tests.

bubble_chart Treatment Measures

The primary focus is treating the underlying disease. Antibiotics should be used for intestinal bacterial infections; for intestinal malignant tumors, anticancer drugs or surgical resection are applied; for certain immune-mediated diseases, immunosuppressants or steroid hormones may be employed. Symptomatic management includes a low-salt diet and the use of diuretics, while malnourished patients may receive supplementation for specific nutrient deficiencies. Intravenous albumin supplementation can be effective, and whole blood transfusion may be administered if necessary.