Still, it sounds like something is amiss. There is lots here in CWD about it. You might want to consider it as a choice to learn about the three year old child's current state. Now, the nine year old son with diabetes and the kidney questions. Testing for protein is a tricky business.
Children frequently have more protein in the urine when they are upright than they do when sleeping.
That's why it is important to know when the urine was collected. It is hard to get 24 hour urines, so I use overnight urine samples. I don't know how your son's urine was collected, etc. Also, if the creatinine clearance was done, it must be corrected for body size. It can get complicated.