Proteinuria in men can be caused by physiological or pathological factors: the main causes of physiological proteinuria are strenuous exercise and exposure to heat sources, for example, in extremely cold environments. Patients who have their urine checked after a long run or after playing basketball or soccer may have urine containing proteinuria at this time. When the patient works in a boiler room or steel mill, the test urine may also have urine protein. Pathological factors are mostly caused by various nephritis, such as chronic glomerulonephritis, acute glomerulonephritis, and rapidly progressive glomerulonephritis. In addition to proteinuria, these nephritis may be accompanied by symptoms such as hematuria, eyelid or lower extremity edema, elevated blood pressure, and renal insufficiency. Nephrotic syndrome also needs to be considered if the amount of urine protein is relatively high, more than 3.5g of urine protein in 24h. In conclusion, if proteinuria is present, both pathological and physiological factors should be considered, otherwise it is easy to miss the diagnosis.