The normal range of urine osmolality is between 600-1000 mOsm/kg-H2O, and morning urine is usually retained for observation. Urine osmolality can indirectly reflect systemic diseases. If urine osmolality is significantly lower than normal, consider renal tubular damage, which can be seen in hypertensive renal damage, vasculitis nephropathy, etc. If the urine specific gravity is significantly higher than normal, consider the possibility of higher renal tubular concentration function or too little water consumption recently, which indirectly causes urinary tract infection or even urinary tract stones. In this case, it is recommended to drink more water and urinate more often. At the same time, urological ultrasound or abdominal plain film can be checked to exclude urinary stones. If there is a combination of infection or stone, it is recommended to go to hospital for regular treatment.