I need it to be something that wouldn't be discovered right away. So far, I'm thinking of a benign tumor. Would a benign tumor impact the results of a kidney function blood test?
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While searching with these terms gave me lots of information, I could not figure out the answer to my obscure question.
*EDIT* Preferably a condition that would not show up on a urine test, either. Something that can only be found via ultrasound. Character is a wizard whose magical aura disrupts medical machinery, but ends up having a kidney problem that would have been fine had they been able to see it, but since they can't do imaging on him all they have to go on is blood/urine tests, which show up clean. That's why I was thinking along the lines of a benign tumor, because a malignant one would probably show on the blood test.
So, would a benign tumor impact the results of a blood test?