Whether mild proteinuria is nephritis depends on the cause of proteinuria. If it is caused by physiological factors such as fever, strenuous exercise, it is not nephritis; if it is caused by pathologic factors such as glomerulonephritis, interstitial nephritis and so on, this situation is considered as nephritis. 1. Physiological factors: more common in the case of intense exercise, fever, etc., the patient’s kidneys have no organic lesions, no need for special treatment, after resting, the urine protein can usually turn negative by itself, this is not nephritis. 2. Pathologic factors: (1) Glomerulonephritis: glomerulonephritis may cause immune dysfunction, produce in situ immune complexes and circulating immune complexes, leading to the destruction of glomerular basement membrane structure, resulting in the destruction of glomerular filtration barrier, resulting in the emergence of urinary protein, at this time for nephritis. (2) Interstitial nephritis: Urinalysis may show mild to moderate proteinuria (below 2g/d). Microscopic hematuria and aseptic leukocyturia are predominant, and carnal hematuria is rare. At this time, mild proteinuria is nephritis. Mild proteinuria may also have other causes, it is recommended that patients go to the regular hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.