 [ Symptoms ] what increases the risk of getting food allergies [ Disease ] the timing of the last time you had something to drink would not likely affect thes urine results while urine dip stick tests are good tests they are not perfect it is possible you had what is called a false positive test the first time this means it detected something that was not actually there however it is possible to have blood or white blood cells in your urine with no symptoms a repeat third test may be warranted to confirm or possibly even blood tests to make sure nothing shows up there there is a good chance the first test was just wrong it happens and that is why your gp repeated it but continue to work with your doctor to get to the bottom of it