Sodium bicarbonate is used to correct the acid balance in your blood. It should be used to try and maintain your total carbon dioxide level (total CO2) to greater than 22 milliequivalents per liter (mEq/L). It should not cause any change in your creatinine or the blood urea nitrogen (BUN). I am unable to provide a reason for your change in kidney function testing based on the information that you provide.
For more information on CKD click here: