Nephrotic syndrome

　　Secondary nephrotic syndrome, which is secondary to systemic diseases, has a wide range of causes and is complex. It can be briefly summarized into the following aspects.

　　1. Infectious diseases:(1) Bacterial infection: such as Streptococcus, Staphylococcus, pneumococcus, Salmonella, leprosy bacillus, and syphilis spirochete infection. (2) Viral infection: such as hepatitis B virus, cytomegalovirus, Coxsackievirus, and adenovirus infection. (3) Protozoan infection: such as malaria parasite, plasmodium, and so on. (4) Parasitic infection: various schistosomes, trypanosomes, filariae, and so on.

　　2. Multi-system and connective tissue diseases: Such as systemic lupus erythematosus, allergic vasculitis, rheumatoid arthritis, dermatomyositis, polyarteritis nodosa, Sjögren's syndrome, allergic purpura, sarcoidosis, psoriasis, and so on.

　　3. Allergens:Such as snake bite, bee sting, pollen, serum, vaccine, penicillamine, probenecid, and so on.

　　4. Metabolic diseases:Such as diabetic nephropathy, amyloidosis, myxedema, and so on.

　　5. Nephrotoxic substances:Such as mercury, bismuth, gold, trimethyl ketone, and so on.

　　6. Tumors:Including how to deal with Hodgkin's disease, lymphoma, multiple myeloma, renal cancer, colon cancer, gastric cancer, and so on.

　　7. Other:Such as preeclampsia, renal artery stenosis, renal vein thrombosis, reflux nephropathy, chronic rejection of renal transplantation, chronic heart failure, and so on.

　　Nephrotic syndrome is a relatively refractory clinical syndrome caused by glomerular filtration membrane damage and fibrosis due to various reasons. If not treated promptly, it can lead to serious complications. Common complications of nephrotic syndrome include:

　　1, Infection:The loss of large amounts of proteinuria affects antibody formation, leading to decreased immune function in patients, causing infections such as upper respiratory tract infections, skin infections, primary peritonitis, urinary tract infections, and even triggering sepsis.

　　2, Coronary heart disease:Patients with nephrotic syndrome often have hyperlipidemia and a hypercoagulable state of blood, making them prone to coronary heart disease.

　　3, Thrombosis:Arteriovenous thrombosis, with renal vein thrombosis being common, presenting with severe lumbar and abdominal pain, hematuria, and other symptoms.

　　4, Acute renal failure:Patients with nephrotic syndrome often have low blood volume and hypercoagulability due to large amounts of proteinuria, hypoalbuminemia, and hyperlipidemia. Vomiting, diarrhea, the use of antihypertensive drugs and diuretics, and excessive diuresis can all cause a sudden decrease in renal blood perfusion, leading to a decrease in glomerular filtration rate and resulting in acute renal failure.

　　5, Electrolyte disorder:Recurrent use of diuretics or long-term unreasonable salt restriction can lead to secondary hyponatremia and decreased blood volume in patients with nephrotic syndrome. The use of adrenal cortical hormones and large amounts of diuretics can lead to excessive urination, and if blood potassium is not replenished in a timely manner, hypokalemia may occur.

　　Nephrotic syndrome refers to a group of clinical symptoms, including large amounts of proteinuria, hypoalbuminemia, hyperlipidemia, and edema. Severe cases may have serous cavity effusion and anuria.

　　1, Large amounts of proteinuria:The daily urine protein excretion in normal adults does not exceed 150 mg, while patients with nephrotic syndrome have proteinuria exceeding 3.5 grams per day, and may have lipuria. The production of large amounts of proteinuria is due to abnormal glomerular filtration membrane.

　　2, Hypoalbuminemia:Hypoalbuminemia is seen in most patients with nephrotic syndrome, with serum albumin less than 30 grams per liter. The main reason is the loss of albumin in urine, but the two are not completely parallel because the plasma albumin level is the result of a balance between albumin synthesis and catabolic metabolism.

　　3, Hyperlipidemia:Hyperlipidemia is related to hypoalbuminemia, and patients may present with lipuria, where double-refractive lipid bodies appear in the urine, which may be epithelial cells containing cholesterol or lipid casts.

　　4, Edema:Different degrees of edema, often the initial symptom of nephrotic syndrome, usually occurs stealthily. Initially, edema may be seen in the eyelids, face, and ankles upon waking in the morning. As the condition progresses, edema can spread to the entire body. Severe cases may have serous cavity effusion, ascites, pericardial effusion, mediastinal effusion, scrotal or labial edema, and may also develop pulmonary edema.

　　Nephrotic syndrome is a clinical syndrome caused by increased permeability of the glomerular basement membrane, leading to the loss of a large amount of plasma protein in urine. It poses a significant threat to health and requires proactive measures for prevention to avoid its harmful effects. To prevent nephrotic syndrome, attention should be paid to the following points:

　　1. Low-salt diet, because salt can make the blood concentrate, which will further increase the workload of the kidneys, and have an adverse effect on health. In addition, drink more water, as more water intake will lead to more urination, which helps to excrete toxins in the kidneys and can play a protective role for the kidneys.

　　2. Exercise more, but pay attention to the combination of work and rest, exercise more, control weight and blood pressure, and reduce the burden on the kidneys.

　　3. Do not take painkillers arbitrarily, as research shows that many kidney disease patients have kidney problems caused by the retention of painkillers in the kidneys.

　　4. Regular check-ups, regular physical examinations are very important because early detection of nephrotic syndrome is relatively easy to treat.

　　5. Prevent infection, treat infections promptly, keep the skin clean, and prevent skin injury.

　　Patients with nephrotic syndrome often present with large amounts of proteinuria, edema, hypoalbuminemia, and hyperlipidemia. In combination with the patient's symptoms, some related examinations need to be done to further confirm the diagnosis.

　　1. Urinalysis:Through urine protein quantification and urine sediment microscopic examination, it is possible to preliminarily determine whether there is glomerular lesion.

　　2. 24-hour urine protein excretion:A 24-hour urine protein excretion exceeding 3.5 grams is a necessary condition for the diagnosis of nephrotic syndrome.

　　3. Plasma protein determination:A plasma albumin level below 3 grams per liter is a necessary condition for the diagnosis of nephrotic syndrome.

　　4. Lipid determination:Patients with nephrotic syndrome often have lipid metabolism disorders and elevated blood lipids.

　　5. Renal biopsy:Ultrastructure and immunopathological observations can be used to provide morphological evidence.

　　6. Renal function examination:During the oliguria phase, there may be temporary mild azotemia. The renal function of simple nephrotic syndrome is mostly normal. If there is varying degrees of renal insufficiency, with elevated blood creatinine and blood urea nitrogen levels, it indicates nephrotic nephritis.

　　While receiving active treatment, nephrotic syndrome patients should also pay attention to their daily diet. The dietary principles for nephrotic syndrome patients are:

　　1. Control sodium salt intake:When nephrotic syndrome patients have edema, they should follow a low-salt diet to avoid exacerbating edema. It is generally advisable to consume no more than 2g of salt per day, and to avoid pickled foods, use less monosodium glutamate and baking soda. When edema subsides and plasma protein approaches normal levels, normal diet can be resumed.

　　2. Limit fat intake:Patients with nephrotic syndrome have hyperlipidemia, which can cause atherosclerosis and glomerular injury and sclerosis, so the intake of foods rich in cholesterol and fat such as animal internal organs, fatty meat, and certain seafood should be restricted.

　　3. Supplement trace elements:Due to the increased permeability of the glomerular basement membrane in patients with nephrotic syndrome, in addition to the loss of a large amount of protein in urine, certain trace elements and hormones bound to proteins are also lost, leading to a deficiency of magnesium, zinc, calcium, iron, and other elements in the human body. Appropriate supplementation should be given. It is advisable to eat more vegetables, fruits, mixed grains, seafood, and other foods rich in vitamins and trace elements.

　　4. Increase protein intake appropriately:Patients with nephrotic syndrome have a large amount of plasma protein excreted in the urine, resulting in a decrease in human protein and a state of protein malnutrition. Hypoproteinemia causes a decrease in plasma colloid osmotic pressure, leading to persistent edema that is difficult to resolve, and the body's resistance also decreases. Therefore, in the absence of renal failure, high-quality high-protein diet should be provided in the early and acute stages, such as fish and meat, which can help alleviate hypoproteinemia and some complications.

　　Prevention:The onset and prognosis of this disease are related to many factors. Prevention should start with personal health, pay attention to a reasonable diet, enhance physical fitness, improve immunity, avoid contact with toxic substances, harmful drugs, and chemical substances to reduce their damage to the body, and actively prevent infections and the occurrence of various diseases. The important factors affecting the efficacy and long-term prognosis of nephrotic syndrome patients are the complications of nephrotic syndrome, which should be actively prevented and treated.

　　Patients with nephrotic syndrome often have edema of the gastrointestinal mucosa and ascites, which affects digestion and absorption. It is advisable to consume easily digestible, light, semi-liquid foods. During kidney disease, a large amount of urinary protein is lost, resulting in a low protein state in the body. Before the late 1980s, high-protein diet (1.2～1.5 grams/kg.d) was advocated to alleviate hypoproteinemia and the associated complications. However, animal experiments and observations of human kidney diseases have confirmed that high-protein diet, although it increases the synthesis of albumin in the liver, also increases the excretion of urinary protein and does not help correct hypoproteinemia. On the contrary, it accelerates the non-inflammatory sclerosis of glomeruli. Limiting protein intake can slow down the progression of chronic renal function damage. Therefore, it is currently recommended to consume high-quality protein, 0.7～1.0 grams per kilogram of body weight per day. Patients with nephrotic syndrome almost all have hyperlipidemia, so it is advisable to limit the intake of animal fats and provide a rich supply of polyunsaturated fatty acids (such as fish oil) and vegetable oils (such as soybean oil, rapeseed oil, sesame oil). For those with severe edema, it is advisable to limit the intake of sodium, with less than 3 grams of salt per day, and appropriate supplementation of trace elements.