Acute glomerulonephritis

　　Commonly caused by infection with beta-hemolytic streptococcus 'nephritogenic strains' (commonly type A12, etc.), which are often found after upper respiratory tract infections, scarlet fever, skin infections, and other streptococcal infections. The severity of the infection is not always consistent with the onset and severity of acute nephritis. The disease is mainly caused by an immune response induced by infection.

　　The common complications of acute glomerulonephritis are as follows:

　　1. Severe circulatory congestion and heart failure:Due to water and sodium retention, clinical symptoms such as excessive water load may occur, such as severe edema, circulatory congestion, heart failure, and even pulmonary edema. The main symptoms are shortness of breath, inability to lie flat, chest tightness, cough, moist rales at the base of the lung, enlargement of the heart border, liver enlargement, increased heart rate, and galloping rhythm. The early signs of circulatory congestion usually alleviate with diuresis within 1 to 2 weeks.

　　2. Hypertensive encephalopathy:The incidence of China is reported to be 5% to 10%, and diagnosis can be made if the blood pressure is over 18.7/12kPa, accompanied by one of the following symptoms: visual impairment, convulsions, or coma. It usually manifests as severe dizziness, vomiting, drowsiness, confusion, and blackout. In severe cases, there may be sporadic convulsions and coma. Ophthalmoscopic examination often shows retinal arteriolar spasm, hemorrhage, exudation, and optic disc edema.

　　3. Acute renal failure:The incidence rate is 1% to 2%, manifested as oliguria or anuria, increased blood urea nitrogen, varying degrees of hyperkalemia, and metabolic acidosis, etc., which are changes of uremia.

　　Acute glomerulonephritis is more common in male children, usually onset 1-3 weeks after a preceding infection, with an incubation period equivalent to the time required for the body to produce immune complexes after the initial exposure to the pathogenic antigen. The incubation period for respiratory tract infection is shorter than that for skin infection. The disease onset is acute, with varying degrees of severity, with mild cases presenting as an asymptomatic type (only urinary routine abnormalities), typical cases presenting with acute nephritis syndrome, and severe cases may develop into acute renal failure. The prognosis of the disease is generally good, and it can often be clinically cured within a few months. Specifically as follows.

　　1. Hematuria, proteinuria

　　Almost all patients have glomerular源性 hematuria, about 30% of patients may have gross hematuria, often as the initial symptom and reason for seeking medical attention. It may be accompanied by mild to moderate proteinuria, and about 20% of patients present with nephrotic range proteinuria. The urine sediment, in addition to red blood cells, may show an increase in leukocytes and epithelial cells in the early stage, and may also have granular casts and red blood cell casts, etc.

　　2. Edema

　　Edema is often the initial manifestation of the disease, with typical symptoms of facial edema upon waking or mild, non-pitting edema in the lower extremities. A few severe cases may affect the whole body.

　　3. Hypertension

　　Most patients experience transient mild to moderate hypertension, often related to sodium and water retention, which can gradually return to normal after diuresis. A few patients may experience severe hypertension, even hypertensive encephalopathy.

　　4. Abnormal renal function

　　In the early stage of the disease, patients may experience a decrease in glomerular filtration rate, sodium and water retention, leading to a decrease in urine output, and a few patients may even have oliguria (<400ml/d). The renal function may be transiently impaired, manifesting as mild azotemia. The urine output gradually increases after 1-2 weeks, and the renal function can gradually return to normal several days after diuresis. Only a very few patients may present with acute renal failure, which needs to be distinguished from rapidly progressive glomerulonephritis.

　　5. Congestive heart failure

　　It often occurs in the acute stage, with severe water and sodium retention and hypertension as important triggers, which require emergency treatment.

　　6. Abnormal immunological examination

　　Transient decrease in serum complement C3: More than 2 weeks after onset, gradually returns to normal within 8 weeks, which is of great significance for the diagnosis of the disease. The titer of serum anti-streptolysin O in patients may increase.

　　The prevention of acute glomerulonephritis should focus on strengthening physical fitness, improving the body's defense function, and maintaining environmental hygiene to reduce upper respiratory tract infections. Attention should be paid to cleanliness in cases of tonsillitis and pharyngitis, and the occurrence of skin abscesses should be reduced. Active treatment should be carried out when these diseases occur, and chronic infection foci should be cleared. Children in collective living can use antibiotics for prevention to reduce the incidence of disease during streptococcal infections. In recent years, the incidence of acute glomerulonephritis has decreased compared to the past.

　　Acute glomerulonephritis is more common in male children, with an acute onset and varying degrees of severity. The specific examination is as follows:

　　1. Urinalysis:Microscopic examination shows a marked increase in red blood cells, urine sediment examination shows red blood cells up to 10 in the field of vision per high-power microscope, and granular casts, red blood cell casts, renal tubular epithelial cells, and leukocytes, as well as proteinuria can also be seen. Such changes in routine urine examination often last for several months, and fibrin degradation products (FDP) can also appear in the urine.

　　2. Blood test:Commonly normochromic, normocytic anemia, hemoglobin is generally 100g/L to 120g/L, mainly related to water and sodium retention, blood dilution, and equal to the degree of uremia. White blood cell count is normal or increased, ESR is often accelerated in the acute phase. Renal function examination shows that the glomerular filtration rate (GFR) in the acute phase decreases, and some patients may have significant azotemia, with increased blood BUN, Scr, and may also appear hyperkalemia, hyponatremia, hyperchloric acidosis, decreased plasma protein, and in severe cases, if oliguria, anuria, or acute renal insufficiency, significant azotemia can be seen, accompanied by metabolic acidosis and electrolyte disorder, but the change of renal tubular function is slight.

　　3. Bacteriological and serological examination:About half of the patients without antibiotic treatment show group A hemolytic streptococcus positive in throat or skin pus secretion culture. About 70% of patients have a titer of antistreptolysin O (ASO) in serum greater than 400U.

　　4. Blood biochemistry examination:For patients with severe edema and large amounts of proteinuria, determination of plasma total protein, albumin/globulin ratio, blood cholesterol, triglycerides, and lipoproteins should be performed to determine the presence of hypoproteinemia and hyperlipidemia.

　　5. Detection of anti-nuclear antibody:Detection of anti-dsDNA antibody, anti-Sm antibody, anti-RNP antibody, and anti-histone antibody to exclude systemic lupus erythematosus.

　　6. Abdominal X-ray:The renal shadow can be normal or enlarged.

　　7. Chest X-ray:The heart can be normal or slightly enlarged, often accompanied by pulmonary congestion.

　　Acute glomerulonephritis is one of the most easily treatable kidney diseases, and in most cases, hospitalization is not necessary. During the illness, if appropriate treatment is adopted and scientific diet is supplemented, the condition can be controlled quickly. The specific details are as follows.

　　1. The intake of protein should be determined according to the condition. If the patient has renal insufficiency or azotemia, protein intake should be restricted, and high biological value proteins such as milk and eggs should be used to reduce the burden on the kidney's excretion of nitrogenous substances; if there is severe renal insufficiency or azotemia, further reduction of protein intake is required. To reduce the intake of non-essential amino acids in staple foods, corn starch, lotus root starch, and wheat starch can be used instead of staple foods; if there are no above conditions or the condition improves, protein intake can be gradually increased, and 1 gram of protein per kilogram of body weight can be provided daily.

　　2. Carbohydrate and fat intake can generally be unrestricted. It is necessary to ensure an adequate supply of calories.

　　3. For patients with edema and hypertension symptoms, it is necessary to adopt a low-salt, salt-free, or low-sodium diet according to the condition. Low-salt means the daily salt intake is less than 3 grams; salt-free means that no salt is added to the diet, and no salt-containing foods are consumed; low-sodium food means that the daily dietary sodium content should not exceed 1000 milligrams, in addition to salt, foods with high sodium content (such as alkali) should also be controlled.

　　4. For patients with persistent oliguria and hyperkalemia, it is necessary to avoid foods high in potassium content, such as fruits and various fruit juices.

　　5. Ensure an adequate supply of foods rich in vitamin A, B族 vitamins, and vitamin C, especially fresh vegetables and fruits should be eaten as much as possible.

　　Most cases of acute glomerulonephritis can be cured spontaneously, so for mild cases, it is not necessary to use too much medication, and the following measures can be taken.

　　1. Rest

　　Rest is very important for preventing the worsening of symptoms and promoting the improvement of the disease. There is no consensus on whether those with significant edema and hypertension symptoms should rest in bed completely, but if slight activity causes symptoms and abnormalities in urine routine to worsen, it is still advisable to rest in bed. It should be avoided to be exposed to cold and dampness, as cold can cause vasoconstriction of the renal arterioles, exacerbating renal ischemia.

　　2. Diet

　　In the early stages of the disease, dietary control is very important. In principle, low-salt diet and water restriction are given, as most patients have edema and hypertension; if the blood pressure is very high and the edema is significant, a salt-free diet should be given, with daily fluid intake limited to 1000ml or less. For those with anuria, treatment for acute renal failure should be administered. The daily protein intake for adults should be between 30g to 40g, or calculated as 0.6g/kg/d, to avoid increasing the burden on the kidneys.

　　3. Control Infection

　　For precursor infections that still exist in the body, such as tonsillitis, pharyngitis, impetigo, sinusitis, otitis media, and others, active treatment should be sought. Since the focus of precursor infections is sometimes concealed and difficult to detect, even if an acute glomerulonephritis with no clear focus of infection is not found, it is generally recommended to use penicillin (for those allergic to use lincomycin or erythromycin) for routine treatment for 10 to 14 days to prevent antigens from continuing to侵入 the body, in order to prevent the recurrence or progression of glomerulonephritis. It should be avoided to use antibiotics that are harmful to the kidneys.