Derick is a 15-year-old boy who was previously healthy. Three months ago, he noticed a foaming appearance to his urine, and the condition was worsening. He sought advice from a private doctor. Upon examination, his urine albustix was 4+, with a trace of red blood cells, and he was referred. There was no history of gross haematuria, no skin rash, nor any arthritis. There was no preceding history of respiratory tract infection. There were no urinary symptoms. He has no hearing problem, and a family history of renal disease was absent. Upon physical examination, his vitals were stable. His body weight was 42.4 kg (10th centile), body height 160 cm (10th centile), and office blood pressure was 121/77 mmHg. There was no ankle oedema, no puffy face, and abdominal examination was uneventful. Can you explain what might be occurring to Derick and how would you approach his proteinuria in this scenario?