Whether or not a pH of 6.5 is normal depends on what the specimen being tested is. If it is urine pH is normal, if it is arterial blood and pleural fluid pH is not normal. 1. Urine pH 6.5 is normal. 2. Arterial blood pH of 6.5 is abnormal. The normal value of arterial blood pH is 7.35-7.45. pH 6.5 indicates that the patient already has severe acidosis. The acid-base balance needs to be corrected immediately. 3. pH 6.5 of pleural fluid is not normal. The normal value of pleural fluid pH is usually around 7.6. pH 6.5 needs to identify whether the disease is tuberculosis or malignant pleural fluid. If the patient’s pH value is not normal, if you feel uncomfortable, you need to go to the regular hospital in time for examination and treatment.