Your serum creartine is 1.9? This means potentially an impairment in kidney function, and is a indicator of chronic kidney disease. I think your doctor will tell you more about the test, including eGFR value, you'll need to be careful about the protein intake according to the eGFR level. When the doctor discusses with you, I'm sure he/she will let you know what you need to do, medicaiton and lifestyle. Chronic kidney disease is usually associated to high blood pressure, high blood sugar, if you do have one of these, your doctor will also evaluate and see if you're managing these fine. These are called the underling diseases.