BUN clinically refers to urea nitrogen, a type of kidney function test that also includes creatinine and uric acid, to assess kidney disease in a comprehensive manner. Urea nitrogen can generally be significantly higher than normal in renal failure, and the primary disease can be further identified. The most common primary diseases are chronic glomerulonephritis, renal arteriosclerosis, hypertensive nephropathy, diabetic nephropathy, myeloma-associated nephropathy, etc. Further investigation of routine blood, urine, liver function, ionized renal function, urological ultrasound, PTH and other related examinations are needed, which can actively find the primary disease and can clarify the treatment plan and prognosis of the patient. In addition, comprehensive treatment, such as the application of kidney preservation drugs, urinary toxicity Qing granules, Bai Ling capsule, Jin Shui Bao, compound alpha-keto acid and other drugs.