It can screen for lesions in the urinary system such as kidney, ureter, bladder or urethra, and sometimes can be used as a diagnostic clue for organ systems or certain systemic diseases (such as lupus erythematosus). Some patients worry about their kidney problems because of “positive urine protein”, so they bring their medical reports to the clinic for consultation. Does “proteinuria” matter? A normal person will excrete 40~100 mg of urine protein per day, up to 150 mg, so once the urine protein exceeds 150 mg per day, it is considered abnormal. There are two types of urine protein tests: qualitative and quantitative. The higher the (+) sign, the higher the “concentration” of protein in the urine. Urine test paper qualitative results are often divided into: 1, negative (urine protein concentration of less than 0.1 g / L); 2, + (urine protein concentration of 0.1 to 1.0 g / L); 3, + + + (urine protein concentration of 1.0 to 2.0 g / l); 4, + + + + (urine protein concentration of 2.0 to 4.0 g / l); 5, ++++ (urine protein of 4.0 g / L or more). When the urine protein reaction is positive, there are several possibilities: 1. False positive urine protein: When the urine is alkaline (pH>7.5), concentrated (drink less water or sweat more), blood in the urine, mixed with semen, vaginal secretions or the use of penicillin, sulfonamides and other drugs, sometimes the urine protein reaction will be positive, but there is not really more than normal amount of protein urine present. On the contrary, if the urine is too dilute it will be pseudo-negative. 2, temporary or functional proteinuria: After strenuous exercise, high fever, pregnancy, menstruation, sudden cold, mental stress, heart failure, elevated blood pressure, epileptic seizures, etc., temporary or functional proteinuria will appear, but after the stress factors are eliminated, the urine examination will return to normal. In addition, temporary proteinuria can occur when there is a urinary tract infection, but once the infection is controlled, the proteinuria will disappear. 3, postural (standing) proteinuria: closely related to the patient’s body position change, proteinuria only appears when standing, usually temporary and often found in young people. Usually the patient’s urine is negative for protein in the morning, but after a long period of activity, walking, strenuous exercise, or forward bending or standing, proteinuria will appear, and when the patient is lying down and tested again, the urine protein will disappear. This kind of patient is usually younger than 30 years old, with urine protein less than 1 gram per day and normal endogenous creatinine clearance (Ccr), as long as the blood pressure is measured regularly and followed up every year; if older than 30 years old, the blood pressure needs to be measured regularly and checked every 6 months. Some people may have persistent proteinuria that disappears gradually over 10-20 years, and it usually gets better on its own without treatment. A few people with frequent proteinuria may have glomerulopathy and may become chronic nephritis or uremic syndrome, so long-term outpatient follow-up observation is necessary. 4, intermittent proteinuria: proteinuria comes and goes, such as recurrent infections of cystitis, pyelonephritis, will appear urine protein; while hypertension, heart failure and other diseases will appear intermittent urine protein with the good and bad of the disease. 5, persistent proteinuria (pathological proteinuria): that is, proteinuria is present in every urine test, when irreversible destruction of the glomerulus or tubules occurs. Primary disease of the kidney or urinary tract, but also diseases of other organs (such as diabetes mellitus) or the effect of nephrotoxic drugs on the kidney or urinary tract. The rate of deterioration of kidney function varies depending on the etiology. Glomerular diseases are the main cause of pathological proteinuria and can be broadly divided into: (1) primary glomerular diseases including acute glomerulonephritis (acute nephritis), chronic glomerulonephritis; (2) secondary glomerular diseases: glomerular diseases caused by other diseases in the body are called secondary glomerular diseases, such as nephropathy caused by systemic lupus erythematosus, diabetes mellitus, etc. Don’t panic when you find urine protein in the physical examination report, because most of them may be false positives or temporary proteinuria. If the urine protein is trace to 2+, it should be retested twice to three times, preferably the first time you wake up in the morning. If the retest result is negative, it may only be temporary proteinuria, if the qualitative test is 3+ or 4+, or if the retest still continues to be positive, further tests such as 24-hour urine collection, other blood tests, kidney ultrasound or kidney biopsy should be arranged to further clarify the cause.