<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been experiencing thirst, melena, impotence, leg stiffness or tightness and some symptoms related to my kidneys. What could be the possible disease?  <response>: Based on the symptoms you described, you might be suffering from primary kidney disease. It is important to carry out further tests to confirm the diagnosis, and then start a personalized treatment plan to manage your symptoms and improve your kidney function. 