This is a valid concern for someone with IgAN. Foamy urine can indicate protein loss through kidneys, a key symptom of IgAN. While increased water intake may have temporarily reduced the appearance, a GFR of 48 indicates moderate kidney function decline. It's positive that your BP is controlled, but please consult your nephrologist soon. They may want to check your urine protein levels and consider additional treatments to protect your kidney function.

Consider bringing a first-morning urine sample to your next appointment for the most accurate protein testing.