1.What is nephrotic syndrome? Nephrotic syndrome is a general term for various diseases causing renal lesions with four identical clinical manifestations, mainly referring to: (1) a decrease in serum albumin, with a concentration of less than 30g/L; (2) a large amount of protein in the urine, with protein equal to or more than 3.5g (g) in the urine discharged in 24 hours; (3) elevated blood lipids, including cholesterol and triglycerides, especially the elevation of cholesterol is more obvious. The concentration of cholesterol in normal people is the concentration of triglycerides, but patients with nephrotic syndrome often exceed the normal value by many, or even several times; (4) patients may have edema, the lighter the dorsum of the foot swelling, acupressure appears depression, the more serious can appear below the knee swelling, serious cases appear the whole body swelling, or even pneumoperitoneum, pneumothorax, more serious, in the body where the needle will also emerge water. The above four manifestations are often referred to as “three highs and one low”. However, not all of the above clinical manifestations may be present, as long as (1) and (2) are present, the diagnosis can be established with the clinical situation. 2.What are the diseases that cause nephrotic syndrome? What is the difference between nephrotic syndrome and what is commonly referred to as nephrotic syndrome? There are many diseases that cause nephrotic syndrome, which can be broadly classified as follows: (a) Infections: bacterial infections such as streptococcus, syphilis leprosy and other infections. Viral infections, such as hepatitis B, infectious mononucleosis, cytomegalovirus and other infections. Parasitic infections, such as malaria, schistosomiasis, toxoplasma and helminth infections. (ii) Systemic diseases: systemic lupus erythematosus, allergic purpura, necrotizing vasculitis, rheumatoid arthritis and other diseases. (C) Metabolic diseases: diabetes mellitus. (D) Tumors: solid tumors of lung, stomach, colon, kidney, ovary, thyroid, breast, etc., lymphoma and leukemia, etc. (v) Drugs, poisoning and allergy: such as mercury, organic gold, silver, penicillamine, propofol, drug Hainlo, bee venom, snake venom, vaccine allergy. (vi) hereditary diseases: congenital nephropathy. (vii) Other: gestational hypertensive syndrome, renal artery stenosis, malignant nephrosclerosis. From the above disease spectrum, there are often serious diseases hidden behind the nephrotic syndrome. And in other words, the above diseases can manifest as nephrotic syndrome at some stage of their development. Therefore, we should actively search for the cause of the disease with a view to finding the real culprit hidden behind the nephrotic syndrome.