Leukocyte esterase + may be the result of diseases such as urethritis, cystitis, pyelonephritis. 1. Urethritis: it is mainly caused by gonococcus and non-gonococcal infections such as Chlamydia trachomatis and Mycoplasma, and it is also related to factors such as direct transmission, indirect transmission and age. Patients often appear urinary frequency, painful urination, urethral itching and other symptoms, some male patients can also be accompanied by fever, pain during sexual intercourse, cloudy urine and other phenomena, while male patients can be accompanied by hematuria, blood in semen and other conditions, and can also be manifested as leukocyte esterase +. 2. Cystitis: usually caused by bacterial infection, and also related to foreign objects, drugs, chemicals, radiation therapy and other factors, and low immunity, urinary flow obstruction and other conditions, can also induce cystitis. Patients often appear urinary urgency, dysuria, urinary frequency, lower abdominal pain and other symptoms, and in severe cases, similar to urinary incontinence, some patients may also be accompanied by hematuria, lower abdominal pressure, etc., and may also appear in leukocyte esterase + situation. 3. Pyelonephritis: It is usually caused by bacterial infection, and is also related to urinary tract obstruction, gender, pregnancy, and structural abnormalities of the urinary system. Patients often have fever, chills, urinary pain, frequent urination and other symptoms, some patients also have generalized pain, nausea, vomiting, hematuria and other phenomena. And patients may also show leukocyte esterase + during examination. It is recommended that patients with test results showing leukocyte esterase +, timely and targeted treatment according to the cause of the disease.