High urea nitrogen creatinine is caused by renal insufficiency. Renal insufficiency is caused by the destruction of the glomerulus from various causes, thus causing serious disorders in the body in excreting metabolic wastes and regulating water-electrolyte balance, etc. It can be divided into acute renal insufficiency and chronic renal insufficiency. Renal insufficiency is a functional diagnosis that causes renal insufficiency, which can be divided into primary kidney diseases, such as acute glomerulonephritis, chronic glomerulonephritis, acute interstitial nephritis, chronic interstitial nephritis, acute progressive nephritis and so on. Secondary kidney diseases, such as diabetic nephropathy, lupus nephritis, etc.