MRCP2-3853

MRCP2-3853

A 65-year-old woman presented to the rheumatology clinic for follow-up of her rheumatoid arthritis. Upon examination, she displayed symptoms and signs of active synovitis with elevated inflammatory markers. She had been receiving IM sodium aurothiomalate 50 mg once a week for the past six months and had recently completed a course of diclofenac 50 mg three times a day. Laboratory tests revealed a serum sodium level of 138 mmol/L (137-144), serum potassium level of 4.9 mmol/L (3.5-4.9), serum urea level of 12 mmol/L (2.5-7.5), and serum creatinine level of 290 µmol/L (60-110). A urine dipstick test showed protein and blood levels of ++, while a 24-hour urine collection revealed a protein level of 0.4 g/24hr (<0.2). Her renal function had been normal during her last clinic visit two months prior. What is the most likely cause of the decline in renal function?