Proteinuria 3+ suggests positive urine protein, which may be caused by physiological reasons such as strenuous exercise, fever, or pathological reasons such as reduced glomerular filtration capacity and tubular reabsorption disorders. 1. Physiological reasons: physiological proteinuria is more common in the case of strenuous exercise, fever, etc., the patient’s kidneys have no organic lesions, no special treatment is needed, and after rest, the urine protein can usually turn negative on its own. 2. Pathologic causes: (1) Reduced glomerular filtration capacity: glomerular infection, poisoning, etc., resulting in the destruction of the integrity of the glomerular filtration membrane, reduced permeability, proteinuria, resulting in proteinuria 3+. (2) renal tubular reabsorption disorder: renal tubular lesions, resulting in reduced reabsorption capacity, can not absorb the glomerular filtration of protein, resulting in protein excreted in the urine, will also appear proteinuria 3 +. Proteinuria 3+ can also be caused by other reasons, it is recommended that patients go to the regular hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to target treatment or treatment.