“What lab tests indicate a kidney infection?”

Urine analysis and urine culture.

You need a urinalysis, urine culture, and sensitivity. These are from urine samples. A complete blood count would be helpful also. If the examining physician has a strong suspicion of kidney infection (pain, fever, chills, nausea), they may order a CT scan also. If you think you have an infection, drink lots of water until you get evaluated. But do go get evaluated.
Good luck and feel better.

You can do a Simple Urinalysis