My son had a uti at 7 months old and hasn't had one since. how will we know if this caused renal scarring? are there tests?

UTI in child: Children get urinary tract infections for different reasons than adults. For first time infections in young children, most pediatricians will order an ultrasound of the kidneys and a VCUG (a special xray with contrast to look at urine flow). Undetected problems with the urinary system can eventually lead to kidney disease, especially with undetected and untreated recurrent UTIs.

Pediatric UTI: It would be very unusual for a single UTI in a baby to produce permanent changes in kidney function. What is important is that boys with UTI usually have to be investigated to see if there is a predisposing anatomical defect or some physiological predisposition, since this is not common in males.