The presence of protein in the urine is called proteinuria, also known as urinary protein. Normal urine contains a small amount of small molecules of protein, which cannot be detected by regular urine tests. When protein in the urine increases and can be detected by regular urine tests, it is called proteinuria. Proteinuria is a common manifestation of kidney disease and can also occur in systemic diseases. Causes There are many causes of proteinuria, including functional proteinuria, postural proteinuria or pathological proteinuria. Commonly, they include: after strenuous exercise, extreme periods of fever, eating a high-protein diet; Nutcracker phenomenon; various renal diseases and renal vascular diseases. Clinical manifestations The clinical manifestations of back pain caused by different etiologies vary, for example: 1. Functional proteinuria Functional proteinuria is a mild (24-hour urine protein quantification usually does not exceed 0,5 to 1 gram), temporary proteinuria, and the proteinuria disappears rapidly after the cause is removed. It often occurs in young adults, and can be seen after mental stress, severe cold or heat, long marches, strong physical labor, congestive heart failure, and eating a high protein diet. 2, postural proteinuria Early morning urine without urine protein, gradually appear proteinuria after getting up and activity, long time standing, walking or strengthening the anterior convex posture of the spine, urine protein content increased, lying down after resting for one hour urine protein content reduced or disappeared, mostly occur in lean and long body type of youth or adults. Repeated postural proteinuria requires attention to exclude nephropathy, such as nutcracker phenomenon (also called left renal vein compression syndrome, which is caused by the aorta and superior mesenteric artery squeezing the left renal vein). 3, pathological proteinuria Proteinuria persists, with high protein content in the urine, and routine urinalysis is often combined with hematuria, leukocyturia and tubuluria. It can be accompanied by other renal disease manifestations, such as hypertension, edema, etc. Pathological proteinuria is mainly seen in various glomerular and tubulointerstitial diseases, hereditary nephropathy, renal vascular diseases and other kidney diseases. Commonly, such as: (1) Primary glomerular diseases ①Nephritis can be insidious, acute, acute or chronic. It is often combined with hematuria, hypertension and edema. (2) Nephrotic syndrome with 24-hour urine protein quantification greater than or equal to 3 or 5 grams, accompanied by reduced blood albumin, edema, and hyperlipidemia. ③ renal insufficiency is divided into acute and chronic renal insufficiency. Proteinuria is a manifestation of renal damage. (2) Secondary glomerular diseases ①Lupus nephritis is a manifestation of systemic lupus erythematosus involving the kidney. It is common in women of childbearing age. Depending on the severity of renal involvement, the amount of urine protein may vary from a small amount to a large amount. (2) Purpura nephritis is a manifestation of renal involvement in allergic purpura. The main manifestation is hematuria and proteinuria, which is common in children and can also occur in adults. Most of the proteinuria occurs 2 to 4 weeks after the appearance of purpura. Diabetic nephropathy is a common complication of diabetes mellitus, early kidney involvement, but the urine routine examination of urine protein can be negative, and then gradually appear microalbuminuria, and then develop to a large amount of protein urine, and even end-stage nephropathy, that is, renal failure requires dialysis and other treatment. Gouty nephropathy is characterized by late and mild abnormalities in urinalysis, with only mild proteinuria and a few red blood cells. It may progress to chronic renal failure in late stages. ⑤ Hypertensive nephropathy primary hypertensive disease often occurs 5 to 10 years after the onset of kidney and other damage. Proteinuria due to benign hypertension is usually mild to moderate (24-hour urine protein quantification usually does not exceed 1, 5 to 2 grams) and rarely appears in large amounts. Some combined with microscopic hematuria often show hypertensive left ventricular hypertrophy and cerebral and retinal arteriosclerosis. Another kind of proteinuria caused by malignant hypertension is often sudden, and the 24-hour urine protein quantification can range from little to a lot, mostly accompanied by hematuria and leukocyturia, and renal function mostly deteriorates sharply. (3) Interstitial renal tubular diseases such as pyelonephritis and interstitial nephritis, urine protein is mostly + to +++, and the 24-hour urine protein quantification is mostly <2 grams. (4) Hereditary nephropathies such as Alport syndrome, Fabry disease, thin basement membrane nephropathy, congenital nephrotic syndrome, etc., due to genetic abnormalities, resulting in structural defects of the kidney, leading to varying degrees of proteinuria. (5) Others such as plateau proteinuria can be seen in people who enter the plateau stay from the plain, positive urine protein, quantitative > 400 mg/24 hours, no proteinuria before going to the plateau, onset after entering the plateau, oxygen intake can be improved, return to the plain back to normal. Examination Urine protein examination is divided into qualitative and quantitative examination and special examination: 1. Qualitative examination Urine routine is best for the first urine in the early morning, morning urine is the most concentrated, and postural proteinuria can be excluded. When taking urine specimens, discard the foremost section and leave the middle section of urine. Qualitative examination is only the initial screening test, further quantitative examination should be done for diagnosis of kidney disease, observation of disease and determination of efficacy. 2.Quantitative test 24 hours urine protein quantification, accurate retention of 24 hours urine protein, mix, take urine samples sent for testing. 3.Special examination such as urine protein electrophoresis, urine light chain quantification, urinary ultrasound, renal puncture biopsy, pathological examination, etc. should be performed according to clinical diagnosis and treatment needs. Diagnosis Based on proteinuria, combined with edema, hypertension, diabetes, allergic purpura, gout, use of drugs that damage the kidney and family history, combined with physical examination, such as chest and abdominal fluid, anemia, heart, liver and kidney, fundus examination, and other test results to diagnose. Treatment According to the different causes of the disease, treatment should be given accordingly. Prevention Avoid high protein diet. Regular medical checkups to detect proteinuria as early as possible. People with diabetes mellitus, hypertension and gout for more than 5 to 10 years should have urine tests at least once every half to once a year. Take care to avoid drugs that may cause kidney damage as much as possible: such as antipyretic and analgesic drugs, some antibiotics and Chinese medicine of unknown composition. If necessary, they should be applied under medical supervision.