23rd June 2023

A 45-year-old man with recently diagnosed idiopathic membranous nephropathy presents to hospital with sudden onset right flank pain

A 45-year-old man with recently diagnosed idiopathic membranous nephropathy presents to hospital with sudden onset right flank pain, which is constant in nature, and visible haematuria. Bloods show a serum creatinine of 190μmol/L (previously 100μmol/L) and serum albumin level of 16g/L (normal range 35-50g/L).

What is the most likely diagnosis?