What does high nitrates in urine mean?

NitrAtes or nitrites. Urinary nitrates (from food additives & dietary protein) are generally considered normal. Nitrites, however, indicate the presence of bacteria that can enzymatically change nitrates into nitrites, which are present in urinary tract infections.
Possible infection. Bacteria convert nitrite, a normal byproduct of metabolism excreted into the urine, into nitrate. You should be seen for a urinalysis and possible treatment.