For Stage 3b IgAN, following a kidney-friendly diet is important. While your doctor may not have explicitly prescribed a "renal diet," you should be monitoring:

Protein intake (moderate amounts)
Sodium (limit)
Potassium (may need limits)
Phosphorus (may need limits)
I recommend asking your doctor for a referral to a renal dietitian who can create a personalized meal plan based on your lab values and symptoms. Every IgAN patient is different, so individualized dietary guidance is best.