Pediatric pulmonary hemorrhage-nephritis syndrome

　　First, etiology

　　The exact cause is unclear, and it may be the result of the combined action of multiple causes. It is generally believed that it is related to the following factors:

　　1. Infection

　　Respiratory tract infection, especially influenza virus infection, is the most common cause of the disease. Recent research has found that patients with acquired immune deficiency syndrome (AIDS) are prone to produce anti-GBM antibodies after infection with Pneumocystis carinii pneumonia (Pneumocystis carinii pneumonia). Calderon et al. reported that 3 out of 4 HIV-positive cases had positive anti-IV collagen α3 chain antibodies (anti-GBM antibodies), suggesting that lung alveolar damage during Pneumocystis carinii pneumonia can induce pulmonary hemorrhage-nephritis syndrome.

　　2. Contact

　　Vapors of gasoline, hydrocarbons, turpentine, and inhalation of various hydrocarbons.

　　3. Inhalation

　　Cocaine Perez et al. reported a case of a patient who had been smoking for a long time developing pulmonary hemorrhage-nephritis syndrome 3 weeks after using cocaine.

　　Second, pathogenesis

　　Due to certain causes, the body produces antibodies against the alveolar and glomerular basement membrane at the same time, and they attack the glomeruli and lungs, causing type II hypersensitivity reaction. As for the pathogenesis of immune complex deposition in both alveoli and glomeruli and activation of complement (type III hypersensitivity reaction), there is no definitive explanation.

　　The vast majority of patients have anemia, which can lead to massive or even fatal pulmonary hemorrhage, and respiratory failure may occur; renal dysfunction develops rapidly, and about 81% of cases progress to renal failure; hypertension, enlargement of the liver and spleen, and dilatation of the heart may occur, and there may be abnormal changes in the fundus (including inflammation, tumors, and changes in various blood vessels of the retina, choroid, optic nerve, and vitreous body), purpura, hematochezia, and other symptoms.

　　1. Age

　　The disease can occur from childhood to old age, and is more common in patients aged 16 to 30 (75% to 95.4%), with no racial differences. More cases are seen in children, with males significantly more than females, in a ratio of 3:1 to 10:1.

　　2. Onset may be related to infection

　　Especially in viral infections, Wilson reported 32 cases, 44% of which had a history of preceding upper respiratory tract infection, and 17% had influenza-like symptoms. It is unclear how viral infection or other factors lead to the production of a common antibody against the lung and glomerular basement membrane.

　　3. Pulmonary

　　Pulmonary manifestations: About 2/3 of patients have pulmonary hemorrhage before nephritis, and the time from hemoptysis to the appearance of renal lesions varies, from a few days to several years, with an average of about 3 months. Clinically, hemoptysis is the earliest symptom, with 82% to 86% of patients having blood-stained sputum. It is usually intermittent, small amounts of bright red sputum. In a few cases, massive or even fatal pulmonary hemorrhage may occur. Patients often have symptoms such as shortness of breath and cough, and sometimes chest pain and fever. 10% to 30% of patients may have symptoms of upper respiratory tract infection as the initial symptom. The lung percussion sound is dull, and wet rales can be heard on auscultation. The onset is acute, with fever, cough, expectoration, hemoptysis, dyspnea, and even respiratory failure. The degree of hemoptysis can range from blood-stained sputum to large amounts of hemoptysis.

　　4. Kidneys

　　Proteinuria is often not obvious in the early stages of onset, but it persists throughout the course of the disease, and may even appear as seen in nephrotic syndrome. Up to 80% to 90% of patients present primarily with hematuria, with microscopic hematuria and casts visible. Gross hematuria occurs, and renal dysfunction develops rapidly, with about 81% of cases developing renal failure within one year. On average, dialysis is required to maintain renal function after about 3 and a half months. Elevated blood urea nitrogen and a significant decrease in serum complement are more common. In addition, there may be oliguria, headache, hypertension, edema, and other symptoms.

　　5. Others

　　Anti-basement membrane antibodies bind to the choroid, eyes, ears, and occasionally, corresponding manifestations may occur. According to statistics, about 10% of patients may have abnormal fundus changes, pallor, enlargement of the liver and spleen, enlargement of the heart, purpura, hematochezia, and elevated white blood cells, with neutrophils being the most prominent. The anemia and pulmonary manifestations of this syndrome are very similar to those of hemosiderin pigment deposition in the lungs.

　　Goodpasture syndrome can be rapidly fatal. The cause of death is often pulmonary hemorrhage and respiratory failure, and tracheal intubation, assisted ventilation, and hemodialysis are often required during the acute phase. Subsequent treatment depends on the use of high-dose corticosteroids (methylprednisolone 7-15mg/kg per day, administered intravenously in divided doses), immunosuppressive cyclophosphamide, and repeated hemodialysis to remove anti-glomerular basement membrane antibodies from the circulation. The course of immunosuppressive therapy varies greatly, and in some patients, it may require 12-18 months. Early comprehensive use of these measures can protect renal function, and for late renal disease, long-term hemodialysis or renal transplantation may be performed.

　　1. Urine examination

　　Under the microscope, hematuria, red blood cell casts, granular casts, leukocytosis, and most patients have moderate amounts of proteinuria. A few patients may have large amounts of proteinuria.

　　2. Sputum examination

　　Microscopic examination of sputum shows macrophages containing hemosiderin and blood-stained sputum.

　　3. Blood tests

　　If pulmonary hemorrhage is severe or lasts a long time, there may be more serious small cell, hypochromic anemia, negative Coomb's test, and half of the patients have white blood cell counts exceeding 10×109/L.

　　4. Blood biochemistry

　　Early BUN, Scr, and Ccr are normal, but as the condition progresses, BUN and Scr increase progressively, and Ccr decreases progressively. In severe renal dysfunction, GFR

　　5. Specific tests

　　In the early stage of the disease, the circulating anti-base membrane antibody in the blood is measured by indirect immunofluorescence and radioimmunoassay, and the serum anti-GBM antibody is often positive. The sensitivity of indirect immunofluorescence is 80%, and the sensitivity of radioimmunoassay is greater than 95%. Both have a specificity of up to 99%. If conditions permit, anti-NC1 antibody can be measured by immunoblotting and ELISA methods to specifically diagnose pulmonary hemorrhagic-nephritis syndrome.

　　1. Meet a certain amount of protein supply. Protein should generally be provided according to the normal requirement, 0.8~1.0 grams per kilogram of body weight per day for adults. At the same time, it is necessary to choose proteins with high physiological value, such as eggs, milk, and meat, to compensate for excretion loss, avoid, and treat edema and anemia.

　　2. Eat more foods rich in vitamins. Especially foods containing vitamins A, B2, and C.

　　3. Supplement adequate water to promote diuresis and reduce edema. Water intake does not need to be restricted, and orange juice, watermelon juice, orange juice, fruit juice, and vegetable juice can be consumed.

　　4. Special attention should be paid to the following situations. If hypertension or hyperlipidemia is present, the content of saturated fatty acids and cholesterol in the diet should be limited. For cases with anemia, foods rich in protein and iron, such as liver, kidneys, beef, egg yolks, and green leafy vegetables, should be chosen.

　　The etiology of this disease is not yet clear. It is necessary to actively prevent various triggering factors and endotoxins (toxins, viral infections, bacterial infections, tumors, immune genetic factors can cause fever, microcirculatory disorders, endotoxin shock, and disseminated intravascular coagulation, etc. Endotoxins are heat-resistant and stable, and have weak antigenicity). Avoid stimulating the body to produce antibodies, leading to immune injury and the occurrence of pulmonary hemorrhagic nephritis syndrome.