Q. A 16-year-old boy tells his physician that for the past year he has had intermittent episodes of blood in his urine (hematuria). He states there is no burning or pain, and he is not urinating any more or less than usual. He states he’s had some upper respiratory infections and it seems like the hematuria becomes more prominent at those times. Which of the following is most likely to be found once the boy is diagnosed with Berger’s Disease (IgA nephropathy)?